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(Astronomy) Stars: TV Drama in the Sky
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PostPosted: Sun Nov 20, 2005 10:51 am    Post subject: (Astronomy) Stars: TV Drama in the Sky Reply with quote






TV Drama in the Sky

By Joe Rao
SPACE.com Skywatching Columnist
posted: 18 November 2005
06:24 am ET

When I look at the evening sky this time of year, I think about the long-running successful dramatic family television shows from the mid 1970s through early 1980s, "Little House on the Prairie."

Faithful viewers will remember two mainstays of that show, Harriet and Nels Oleson. Harriet was portrayed as the snobby, rather mean and ridiculously haughty town gossip, while Nels, proprietor of the town's general store, (Olesen's Mercantile) was in contrast, a meek, good-natured soul and a friend to all. Yet, throughout the show's nine-year run, Harriet always remained true to her nasty, gossipy, scheming, troublemaking self, much to Nels' chagrin.

What's any of this got to do with the night sky?

If you look high toward the northern part of the sky around 8 or 9 o'clock in the evening, local time, you'll be able to see what could certainly pass as the celestial version of Harriet and Nels.

Boldly standing out, is a zigzag row of 5 bright stars, which at this time of the year resembles the letter M. Those stars represent Cassiopeia, the Queen of Ethiopia, who like Harriet was apparently pretty much a gossip and a troublemaker in her own right.

In fact, legend tells us that Cassiopeia went so far as to offend none other than the sea god Neptune by boasting that her beauty rivaled that of the Nereides (sea nymphs). Neptune promptly answered Cassiopeia's boasts by flooding the seacoast and sending a vicious sea monster named Cetus, to ravage the land.

In contrast to Queen Cassiopeia, her husband, Cepheus, the King quietly sits nearby and is chiefly composed of relatively dim stars. And much like Nels was with Harriet; poor long-suffering Cepheus is nowhere near as prominent as Cassiopeia.

Nonetheless, on clear November evenings, you should be able to trace out the inverted house-shaped figure of the Ethiopian King, for at this time of year, rather than a King, Cepheus seems to resemble an upside-down church with a steeple. Better yet, maybe we could call it an Alpine ski lodge with a classic steep, snow-shedding roof. Were we to speak of the "Harriet and Nels connection," perhaps we could even refer to it as the building that housed Oleson's Mercantile!

This spire-like figure of stars points toward the general vicinity of Polaris, the North Star, and its dim stellar outline is best seen on moonless transparent nights as it now wheels high above the celestial pole.

At the southernmost point of the spire is Delta Cephei, the most celebrated of the class of variable stars known as the Cepheids. Sky catalogues contain literally hundreds of such pulsating stars that appear to regularly brighten and fade as they expand and contract. Their steady and rhythmical cycles are known with great precision, running from about two to 50 days while their brightness change (in most cases) amounts to about one magnitude.

For example, Delta Cephei has a period of 5 days, 8 hours, 47 minutes and 32 seconds, and at maximum, it sends us about twice as much light as at minimum, varying in magnitude between 3.6 and 4.3.

But more importantly, these Cepheid stars are powerful tools in gauging distances to other galaxies. Harvard Observatory astronomer Henrietta S. Leavitt (1868-1921) discovered in 1912, that there's a close relationship between the period and intrinsic brightness of a Cepheid – the longer the period, the greater the star's luminosity. An astronomer need only determine a Cepheid's period and apparent magnitude. The former value then gives us the star's absolute magnitude; by comparing its apparent and absolute magnitudes it is then easy to calculate the star's distance, which in turn gives the distance of the galaxy in which it is located.

Thus, the relationship between a Cepheid variable star's pulsation rate and the change in its observed luminosity has allowed astronomers to use these stars as "celestial yardsticks" to measure stellar distances. Without the Cepheids, we would have great difficulty in determining distances of tremendously far-away objects like distant galaxies.

Cepheus also hosts some outstanding attractions for binocular viewing.

One is Mu Cephei, better known as William Herschel's Garnet Star. With careful scrutiny, its ruddy cast is apparent even to the unaided eye on a dark night and it is stunning in good binoculars. Another binocular attraction is the Milky Way. You'll enjoy sweeping the Cepheus region on dark nights. An amazing profusion of celestial treasure passes in review before you – star trains and clusters, highly tinted single, double and multiple stars, and even hints of faintly glowing nebulosity and dark obscuring clouds of gas and dust. This rich treasure trove seems fitting for the dim, misty countenance of King Cepheus. Might we then imagine the Milky Way's as his flowing royal gown woven out of stardust?

I bet it would have made even Harriet Oleson envious!

*************************************************************

1 AU, or astronomical unit, is the distance from the Sun to Earth, or about 93 million miles.

Magnitude is the standard by which astronomers measure the apparent brightness of objects that appear in the sky. The lower the number, the brighter the object. The brightest stars in the sky are categorized as zero or first magnitude. Negative magnitudes are reserved for the most brilliant objects: the brightest star is Sirius (-1.4); the full Moon is -12.7; the Sun is -26.7. The faintest stars visible under dark skies are around +6.

Degrees measure apparent sizes of objects or distances in the sky, as seen from our vantage point. The Moon is one-half degree in width. The width of your fist held at arm's length is about 10 degrees. The distance from the horizon to the overhead point (called the zenith) is equal to 90 degrees.

Declination is the angular distance measured in degrees, of a celestial body north or south of the celestial equator. If, for an example, a certain star is said to have a declination of +20 degrees, it is located 20 degrees north of the celestial equator. Declination is to a celestial globe as latitude is to a terrestrial globe.

Arc seconds are sometimes used to define the measurement of a sky object's angular diameter. One degree is equal to 60 arc minutes. One arc minute is equal to 60 arc seconds. The Moon appears (on average), one half-degree across, or 30 arc minutes, or 1800 arc seconds. If the disk of Mars is 20 arc seconds across, we can also say that it is 1/90 the apparent width of the Moon (since 1800 divided by 20 equals 90).

*************************************************************

Questions to explore further this topic:

What are stars?

http://www.frontiernet.net/~kidpower/stars.html
http://www.phys.vt.edu/~jhs/faq/stars.html
http://library.thinkquest.org/25763/lpart1.htm
http://library.thinkquest.org/.....fastar.htm
http://starchild.gsfc.nasa.gov.....stars.html

Do you want to know more about the sun?

http://library.thinkquest.org/25763/lsunanim.htm

What is the history of stargazing?

http://www.phy6.org/stargaze/Ssky.htm
http://www.phy6.org/stargaze/Scelsph.htm
http://www.phy6.org/stargaze/Spolaris.htm

How does one observe stars?

http://library.thinkquest.org/25763/lopart1.htm

Here are ten tips for a fruitful stargazing:

http://www.space.com/spacewatc.....004-1.html

How do stars look through the eyes of a powerful telescope?

http://hubblesite.org/gallery/.....ollection/

Here is an online glossary of terms relevant to stars:

http://library.thinkquest.org/25763/g.htm

GAMES

http://funphysics.jpl.nasa.gov.....llery.html
http://www.toonuniversity.com/.....r-kids.asp
http://spaceplace.jpl.nasa.gov/en/kids/games.shtml


Last edited by adedios on Sat Jan 27, 2007 5:04 pm; edited 2 times in total
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PostPosted: Mon Dec 26, 2005 8:42 pm    Post subject: 'Christmas Tree Cluster' is stellar look at newborn stars Reply with quote

'Christmas Tree Cluster' is stellar look at newborn stars
By Eric Swedlund
ARIZONA DAILY STAR
Tucson, Arizona | Published: 12.26.2005

Astronomers have discovered a perfectly decorated "Christmas Tree" 2,500 light-years away.
New pictures from NASA's Spitzer Space Telescope give astronomers a remarkable first glimpse of newborn stars in a region known as the "Christmas Tree Cluster."
What's most important about the images is the spacing between the young protostars, said Erick T. Young, an astronomer with the University of Arizona's Steward Observatory.
"If you look at the very young stars in the cluster and the spacing between them, it isn't random spacing. They're all about the same distance apart," Young said.
The stars — less than 100,000 years old — are patterned geometrically like spokes in a wheel or a snowflake. The observation is just as scientific theory would predict: new stars in a cluster spaced according to density, temperature and gravity.
In terms of understanding the formation of the star cluster, the images reinforce the basic theory that the gravity and density of the dust and gas cloud are determining factors in the collapse of the cloud into stars.
"This is the first really good demonstration that the theory works on something like a star cluster," Young said.
The "Christmas Tree Cluster" is in the Monoceros, or Unicorn, constellation, 2,500 light-years away and visible in the winter sky to the east of Orion.
The findings reinforce the gravitational collapse theory, formulated by British astronomer James Jeans in the early 1900s, and may hold clues to the formation of our solar system.
"We believe this process of forming stars in a cluster was exactly the same thing that happened with our very own sun 4 1/2 billion years ago," Young said. "It tells us a lot about the history of our own solar system."
The "Christmas Tree Cluster" is about 1 to 3 million years old, too new for planets to have formed.
"Stars we're looking at here are prior to the formation of planets, we think, but it's not going to be very much longer in astronomical terms before planets start forming," Young said.
By examining a lot of different clusters, astronomers will be able to build a more consistent picture of the planet formation process, Young said. Scientists can estimate the age of clusters and sequence them from younger to older, learning more about how stars evolve from formation to old age.
The observations were made a year ago and the astronomers have been working on the data since then, Young said. The results were just published in the Astronomical Journal.
Young is deputy principal investigator for Spitzer's Multiband Imaging Photometer, a UA-built infrared camera that's one of three scientific instruments on the Spitzer Space Telescope, launched in August 2003.
Astronomers combined light from MIP and Spitzer's Infrared Array Camera, developed by the Smithsonian Astrophysical Observatory, in constructing the pictures.
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PostPosted: Tue Jan 10, 2006 11:26 am    Post subject: Hubble Reveals Companion to North Star Reply with quote

Hubble Reveals Companion to North Star
Mon Jan 9, 8:51 PM ET
Associiate Press

Astronomers using the Hubble Space Telescope have revealed something just as constant as the North Star: a hidden companion.

Astronomers now have photographic proof that Polaris, as the bright star and navigational aid is formally called, has two stellar companions.

The first, Polaris B, has been known since 1780 and can easily be seen with even a smaller telescope; the presence of the second, Polaris Ab, has been inferred but eluded direct detection because it was close to Polaris and relatively faint.

The North Star is a super-giant more than 2,000 times brighter than the sun, while its newly photographed second companion is a dwarf star just 2 billion miles from it, astronomers said. They presented the results Monday at the 207th meeting of the American Astronomical Society.

"With Hubble, we've pulled the North Star's companion out of the shadows and into the spotlight," said Howard Bond, of the Space Telescope Science Institute. The Baltimore institute conducts science operations for the orbiting Hubble.

___

On the Net:

http://hubblesite.org/newscent.....s/2006/02/
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PostPosted: Tue Feb 07, 2006 4:49 pm    Post subject: Most Milky Way Stars Are Single Reply with quote

Source: Harvard University
Release No.: 06-11
For Release: Monday, January 30, 2006
Note to editors: An image to accompany this release is online at http://www.cfa.harvard.edu/press/pr0611image.html.

Most Milky Way Stars Are Single

Cambridge, MA - Common wisdom among astronomers holds that most star systems in the Milky Way are multiple, consisting of two or more stars in orbit around each other. Common wisdom is wrong. A new study by Charles Lada of the Harvard-Smithsonian Center for Astrophysics (CfA) demonstrates that most star systems are made up of single stars. Since planets probably are easier to form around single stars, planets also may be more common than previously suspected.

Astronomers have long known that massive, bright stars, including stars like the sun, are most often found to be in multiple star systems. This fact led to the notion that most stars in the universe are multiples. However, more recent studies targeted at low-mass stars have found that these fainter objects rarely occur in multiple systems. Astronomers have known for some time that such low-mass stars, also known as red dwarfs or M stars, are considerably more abundant in space than high-mass stars.

By combining these two facts, Lada came to the realization that most star systems in the Galaxy are composed of solitary red dwarfs.

"By assembling these pieces of the puzzle, the picture that emerged was the complete opposite of what most astronomers have believed," said Lada.

Among very massive stars, known as O- and B-type stars, 80 percent of the systems are thought to be multiple, but these very bright stars are exceedingly rare. Slightly more than half of all the fainter, sun-like stars are multiples. However, only about 25 percent of red dwarf stars have companions. Combined with the fact that about 85 percent of all stars that exist in the Milky Way are red dwarfs, the inescapable conclusion is that upwards of two-thirds of all star systems in the Galaxy consist of single, red dwarf stars.

The high frequency of lone stars suggests that most stars are single from the moment of their birth. If supported by further investigation, this finding may increase the overall applicability of theories that explain the formation of single, sun-like stars. Correspondingly, other star-formation theories that call for most or all stars to begin their lives in multiple-star systems may be less relevant than previously thought.

"It's certainly possible for binary star systems to 'dissolve' into two single stars through stellar encounters," said astronomer Frank Shu of National Tsing Hua University in Taiwan, who was not involved with this discovery. "However, suggesting that mechanism as the dominant method of single-star formation is unlikely to explain Lada's results."

Lada's finding implies that planets also may be more abundant than astronomers realized. Planet formation is difficult in binary star systems where gravitational forces disrupt protoplanetary disks. Although a few planets have been found in binaries, they must orbit far from a close binary pair, or hug one member of a wide binary system, in order to survive. Disks around single stars avoid gravitational disruption and therefore are more likely to form planets.

Interestingly, astronomers recently announced the discovery of a rocky planet only five times more massive than Earth. This is the closest to an Earth-size world yet found, and it is in orbit around a single red dwarf star.

"This new planet may just be the tip of the iceberg," said Lada. "Red dwarfs may be a fertile new hunting ground for finding planets, including ones similar in mass to the earth."

"There could be many planets around red dwarf stars," stated astronomer Dimitar Sasselov of CfA. "It's all in the numbers, and single red dwarfs clearly exist in great numbers."

"This discovery is particularly exciting because the habitable zone for these stars - the region where a planet would be the right temperature for liquid water - is close to the star. Planets that are close to their stars are easier to find. The first truly Earth-like planet we discover might be a world orbiting a red dwarf," added Sasselov.

This research has been submitted to The Astrophysical Journal Letters for publication and is available online at http://arxiv.org/abs/astro-ph/0601375

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
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PostPosted: Fri Feb 09, 2007 1:15 pm    Post subject: Supernovae - Cosmic Lighthouses Reply with quote

Supernovae - Cosmic Lighthouses
Max Planck Institute
9 Feb 2007

Astrophysicists explain the differences in the brightness of supernova explosions


Supernovae stand out in the sky like cosmic lighthouses. Scientists at the Max Planck Institute for Astrophysics and at the National Astronomical Institute of Italy have now found a way to use these cosmic beacons to measure distances in space more accurately. The researchers have been able to show that all supernovae of a certain type explode with the same mass and the same energy - the brightness depends only on how much nickel the supernova contains. This knowledge has allowed the researchers to calibrate the brightness of supernovae with greater precision. This means that in the future, they will use the brightness of a supernova that they are observing through their telescopes to determine more accurately how far away from the Earth the cosmic lighthouse is emitting its rays (Science, 9 February 2007).

For the full article:

http://www.mpg.de/english/illu.....e20070209/
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PostPosted: Fri Feb 16, 2007 8:04 am    Post subject: Peering into the Pillars of Creation Reply with quote

Chandra X-ray Center
15 February 2007

Peering into the Pillars of Creation

A new look at the famous "Pillars of Creation" with NASA’s Chandra X-ray Observatory has allowed astronomers to peer inside the dark columns of gas and dust. This penetrating view of the central region of the Eagle Nebula reveals how much star formation is happening inside these iconic structures.

The Chandra data shows bright X-ray sources in this field, most of which are young stars. In this image, red, green, and blue represent low, medium, and high energy X-rays. The Chandra data have been overlaid on the Hubble Space Telescope image to show the context of these X-ray data.

Very few X-ray sources are found in the pillars themselves. This suggests that the Eagle Nebula may be past its star-forming prime, since young stars are usually bright X-ray sources. However, there are two X-ray objects found near the tips of the pillars. One is a young star about 4 or 5 times as massive as the Sun, visible as the blue source near the tip of the pillar on the left. The other is a lower mass star near the top of the other pillar that is so faint it is not visible in the composite image.

The Chandra observations did not detect X-rays from any of the so-called evaporating gaseous globules, or EGGs. The EGGs are dense, compact pockets of interstellar gas where stars are believed to be forming. The lack of X-rays from these objects may mean that most of the EGGs do not contain enshrouded stars. However, infrared observations have shown that 11 of the 73 EGGs contain infant stellar objects and 4 of these are massive enough to form a star. The stars embedded in these 4 EGGs might be so young that they have not generated X-rays yet and one of them - estimated to have about the mass of the Sun - could represent one of the earliest stages of evolution of our nearest star. The Sun was likely born in a region like the Pillars of Creation.

The pillars and the few stars forming inside them are the last vestiges of star formation in the Eagle Nebula, also known as M16, which peaked several million years earlier. This contrasts strongly with the active star forming regions in other clusters such as NGC 2024, where Chandra sees a dense cluster of embedded young stars.

###
The results were published in the January 1st issue of The Astrophysical Journal and the research team, led by Jeffrey Linsky of the University of Colorado, includes Marc Gagne and Anna Mytyk (West Chester University), Mark McCaughrean (University of Exeter) and Morten Andersen (University of Arizona).
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PostPosted: Fri Mar 09, 2007 8:15 am    Post subject: Gamma-Ray Burst Challenges Theory Reply with quote

Gamma-Ray Burst Challenges Theory
NASA

03.08.07


In a series of landmark observations gathered over a period of four months, NASA's Swift satellite has challenged some of astronomers' fundamental ideas about gamma-ray bursts (GRBs), which are among the most extreme events in our universe. GRBs are the explosive deaths of very massive stars, some of which eject jets that can release in a matter of seconds the same amount of energy that the sun will radiate over its 10-billion-year lifetime.

For the full article:

http://www.nasa.gov/centers/go.....lenge.html
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PostPosted: Mon Mar 26, 2007 9:41 am    Post subject: Birth, death and rebirth: AKARI sees life-cycle of stars in Reply with quote

Particle Physics & Astronomy Research Council
26 March 2007

Birth, death and rebirth: AKARI sees life-cycle of stars in a new light

Scientists using the AKARI infrared satellite, launched in 2006, are releasing their initial results at a conference on March 28th–30th. AKARI has shed new light on both the birth and death of stars and galaxies, phenomena that take place in dusty areas of the Universe and can best be studied in the infra-red. The new results show the intimate connection between star death, which releases material into the interstellar medium (the collection of dust and gas between stars and galaxies), and star birth which gathers up that material.

The AKARI team members at Imperial College, Open University, University of Sussex and University of Groningen are contributing to the data analysis of AKARI's all-sky survey, and contributed to the science of some of these first results.

Dr. Stephen Serjeant (Senior Lecturer in Astrophysics at the Open University) said, "In the deep cosmological survey, AKARI sees the signature of organic molecules in distant redshifted galaxies. These galaxies are in their birth-throes, and this exceptionally sensitive survey with AKARI's superb wide-field camera tells us great deal about the star formation during the birth of galaxies like our own, and their subsequent evolution. AKARI has also shown very clearly how one star can trigger then next generation of new stars in our own Galaxy. Having spent so many years working on this mission, I'm absolutely thrilled to see the first science from AKARI."

Peter Barthel (professor of astronomy at Groningen University, The Netherlands) said, "AKARI will for the first time permit assessment of the far-infrared energy output of many classes of active galaxies, quasars and starburst galaxies. These very energetic objects were much more numerous in the early - that is distant - universe, and so far our knowledge of these objects was rather limited. AKARI will hence increase our understanding of the early phases of the Universe, in which the galaxies such our own Milky Way were being formed and shaped."

New results are being presented at the conference, with five highlights showing:


Evidence for three generations of continuous star formation in a nebula, each dependent on the preceding generation, which will allow detailed study of the processes by which stars form. The distribution of material in the interstellar medium is clearly compacted by parent starts, making nurseries where new stars are born.

The first ever infra-red observations of a supernova remnant in our galactic neighbour, the Small Magellanic Cloud, giving a detailed study of how material ejected in supernova events interacts with the surrounding interstellar medium and supplies it with heavy elements formed in star cores.

First ever observations of red-giant stars being in the earlier evolutionary stage losing large amounts of matter into the interstellar medium. This mechanism had been theoretically predicted as the means by which stars that are too small to undergo supernova (such as our Sun) end their lives. Previous observations had only ever seen this process in red-giants in their last stage, AKARI has observed in it younger stars and seen evidence that this is a sporadic process that stars go through once they enter the red giant phase.

Processes at the heart of an active galactic nucleus. These are compact areas in the centre of galaxies that radiate very brightly. They are thought to contain massive black holes which drive these processes. AKARI has looked inside the heart of one such galaxy, hidden to other telescopes by a thick interstellar medium, and seen the signature of carbon monoxide in the vicinity of the central black hole.

AKARI made a deep cosmological survey, sensitive to the characteristic emission from organic material in the interstellar medium of distant star-forming galaxies. Previous surveys showed that the Universe underwent a period of intense star formation 6 billion years ago (when our own Sun formed). AKARI's survey is ten times bigger than these previous surveys, and finds evidence that this busy spell started even earlier than that.

Professor Keith Mason, CEO of PPARC which funds UK involvement with AKARI, said "AKARI is a prime example of British scientists collaborating with international partners in cutting-edge research. This Japanese-led mission is peering through the cosmic dust of the Universe in unprecedented detail to reveal just how stars are born and die."

Dr. David Clements (postdoctoral research fellow at Imperial College London) said, "AKARI is once again demonstrating the real power of infrared astronomy, with scientific impact at all stages of stellar evolution, in the early life of galaxies, and at the cores of the most energetic objects in the universe. From black holes to young stars infrared astronomy is the key, and AKARI is doing a great job at unlocking these secrets.

Professor Glenn White (The Open University and the CCLRC Rutherford Appleton Laboratory) said: "Observations of the IRC4954/4955 region spectacularly show how one generation of young stars can spawn the next. The bright nebulosity lies at the edge of a cavity, which is blown out by the radiation and winds of the first generation of young stars. This sweeping up process drives shock waves into the surrounding gas, forcing it to collapse under its own gravity, forming the next generation of young stars. Observations of the large scale processes involved in star formation are only now becoming available to observations such as those of the AKARI satellite, because of the exceptional stability and wide area coverage at infrared wavelengths. One of the main objectives in the coming months will be to use the all-sky survey to build a galaxy wide perspective on the processes important to star formation using similar data"

Dr. Chris Pearson (European Space Agency Support Astronomer to the AKARI mission, ISAS, Japan) said, "Almost one year since it opened its eye on the infrared Universe, we are now enjoying the fruits of AKARI's observations. These images in particular demonstrate the unique multi wavelength coverage of AKARI that enables us to dig deeper into the details hidden within our images of the Universe."

Dr. Seb Oliver (Acting Director of the Astronomy Centre at University of Sussex) says. "These new results from the latest infrared mission underline the importance of infrared telescopes in astronomy. For every photon [particle of light] detected by an ordinary optical telescope on Earth another was absorbed by dust and produced infrared photons. A full understanding of quasars and star-formation will only be possible when we understand what happened to all these photons"


###
Notes for Editors

AKARI is a mission of the Japanese space agency, JAXA, carried out with the participation of mainly the following institutes; Nagoya University, The University of Tokyo, National Astronomical Observatory Japan, European Space Agency (ESA), Imperial College London, University of Sussex, The Open University (UK), University of Groningen / SRON (The Netherlands), Seoul National University (Korea). The far-infrared detectors were developed under collaboration with The National Institute of Information and Communications Technology.

Further information on the AKARI project can be found at the project's UK website, http://www.akari.org.uk

Images

Images are available from the PPARC Press Office – details below.

Figure 1.1 (a) Three colour composite image from 9, 11, and 18 micrometre data taken by the IRC onboard AKARI. The actual spatial scale is approximately 13x20 light years. Green crosses indicate the positions of newly born stars. (b) Colour composite image from the FIS data in 65, 90, 140, and 160 micrometres.

Figure 1.2 -- Two colour composite image of the surrounding region of the IRC4954/4955 Nebula with 9 and 18 micrometre data. The size of this image corresponds to 150 light years. The brightest region is IC 4954/4955. White dots are infrared stars. Notice the dark hollow region with a diameter of around 100 light years in the centre of the image.

Fig2.jpg -- Three colour composite image of the supernova remnant B0104-72.3 in the Small Magellanic Cloud by the Near- and Mid-Infrared Camera onboard AKARI. (Blue: 4 micrometres, Green: 7 micrometres, Red: 11 micrometres). The pair of arcs in the central part of the image is the supernova remnant extended over a region of 60x100 light years. The white bar in the bottom-left corner indicates a length of 30 light years.

Fig3.jpg -- Three colour composite image of NGC 104 generated from the data at 3, 11, 24 micrometres taken by the Near- and Mid-Infrared Camera (IRC) onboard AKARI. The image covers a 40 light year square region at the distance of the target. The bright red stars seen in the image are in the later stages of the red-giant evolutionary phase and are losing their mass at rates as much as one millionth of their mass per year. The star newly discovered by the AKARI observation is located in the bottom-left corner (see the red circle). The star seems to be in the early stage of the red-giant phase but is undergoing significant mass loss.

Fig4.jpg --A schematic illustration of the central core of UGC05101. The black hole is sitting at the centre of the brightly emitting region. Enormous energy is released when material spirals down into the black hole. Radiation from this condemned material heats up the surrounding molecular gas. Active star formation is also taking place around this region. The entire active region is covered by cold molecular gas.

Fig5.jpg -- The AKARI deep sky survey at 15 micrometres by the Near- and Mid-Infrared Camera (IRC). White points are all thought to be distant galaxies. The image size is about 10 arcmin squared.

Contacts

Professor Glenn White
Professor of Astronomy
The Open University and The CCLRC Rutherford Appleton Laboratory


Dr Richard Savage
Postdoctoral Research Fellow
University of Sussex


Dr Stephen Serjeant
The Open University



Professor Peter Barthel
Kapteyn Institute, Groningen University


Prof Michael Rowan-Robinson
Professor of Astrophysics
Imperial College, London


Dr Seb Oliver
Reader in Astronomy
University of Sussex


Dr Do Kester
SRON, Netherlands Institute for Space Research
Groningen, The Netherlands

The Particle Physics and Astronomy Research Council (PPARC) is the UK's strategic science investment agency. It funds research, education and public engagement in four areas of science - particle physics, astronomy, cosmology and space science.

PPARC is government funded and provides research grants and studentships to scientists in British universities, gives researchers access to world-class facilities and funds the UK membership of international bodies such as the European Laboratory for Particle Physics (CERN), and the European Space Agency. It also contributes money for the UK telescopes overseas on La Palma, Hawaii, Australia and in Chile, the UK Astronomy Technology Centre at the Royal Observatory, Edinburgh and the MERLIN/VLBI National Facility, which includes the Lovell Telescope at Jodrell Bank observatory.

PPARC is a partner in the British National Space Centre [BNSC] which coordinates the UK's civil space activities.


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PostPosted: Tue Apr 24, 2007 2:08 pm    Post subject: Spectacular star birth pictures on Hubble’s 17th birthday Reply with quote

Spectacular star birth pictures on Hubble’s 17th birthday
ESA

24 April 2007
A 50 light-year-wide view of the Carina Nebula has been released to celebrate the 17th anniversary of the NASA/ESA Hubble Space Telescope.

Carina is an immense nebula situated at an estimated 7 500 light years away in the southern constellation Carina, at the keel of the ship Argo Navis. This panoramic image of the nebula gives us a peek into star formation as it commonly occurs along the dense spiral arms of a galaxy.

For the full article:

http://www.esa.int/esaSC/SEMBZBMJC0F_index_0.html
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PostPosted: Fri May 11, 2007 6:37 am    Post subject: A galactic fossil Reply with quote

Astrophysical Journal Letters
11 May 2007

A galactic fossil

How old are the oldest stars? Using ESO's VLT, astronomers recently measured the age of a star located in our galaxy. The star, a real fossil, is found to be 13.2 billion years old, not very far from the 13.7 billion years age of the universe. The star, HE 1523-0901, was clearly born at the dawn of time.


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http://www.eso.org/outreach/pr.....23-07.html
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PostPosted: Sat May 12, 2007 6:39 am    Post subject: Two Suns in the Sky Reply with quote

Two Suns in the Sky
Emily Sohn


May 16, 2007

Sunsets can be beautiful to watch, but the pinks and purples of a fading Earth day might be boring compared with sunsets on planets outside our solar system. After all, we have only one sun in the sky. It now appears that some planets may have two.
Astronomers at the University of Arizona in Tucson have found evidence of planetlike objects around binary stars—pairs of stars that closely orbit each other. The new research suggests that there may be many worlds with sunsets far more spectacular than our own.

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http://www.sciencenewsforkids......ature1.asp
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PostPosted: Thu May 31, 2007 9:43 am    Post subject: A&A special feature: XMM-Newton deciphers the magnetic p Reply with quote

A&A special feature: XMM-Newton deciphers the magnetic physics around forming stars

Special feature on the XMM-Newton extended survey of the Taurus molecular cloud

(Published in Astronomy & Astrophysics, volume 468-2, June III 2007)

This press release is issued as a collaboration between ESA and Astronomy & Astrophysics.

--------------------------------------------------------------------------------

Astronomy & Astrophysics is publishing a special feature this week dedicated to the XMM-Newton extended survey of the Taurus molecular cloud. One of the main results is the identification of unusual physical processes not known before in forming stars. These unprecedented observations suggest that the gas streams falling down onto the forming star and the jets being ejected from it both play major roles in the production of X-rays.



In a special feature published this week, Astronomy & Astrophysics presents the first round of results from a large project conducted with XMM-Newton, the “XMM-Newton extended survey of the Taurus molecular cloud” (XEST). Starting in 2003, this program has been conducted by an international team of nearly 30 astronomers led by Manuel Güdel (Paul Scherrer Institute, Switzerland).


The large molecular gas cloud in the constellation of Taurus is the nearest star formation region and a star formation test environment for expert theorists and observers alike. The XMM-Newton project has provided by far the most sensitive and comprehensive X-ray survey of this region, for the first time systematically detecting almost all young stars embedded in the cloud as X-ray sources, including many objects with the lowest mass, the so-called brown dwarfs, and stars still in the process of growing, the so-called protostars. These X-rays are thought to be emitted by very hot gas held together by magnetic fields just above the surface of the star, much like the case of the solar corona although with much more intense X-rays.

For the full article and links:

http://www.aanda.org/content/view/233/42/lang,en/
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PostPosted: Wed Jul 04, 2007 9:20 am    Post subject: Stellar fireworks through Hubble’s eyes Reply with quote

Stellar fireworks through Hubble’s eyes
ESA

Galaxy NGC 4449

3 July 2007
Nearly 12.5 million light-years away, in the dwarf galaxy NGC 4449, stellar fireworks on display have been captured by the Hubble Space Telescope.

NGC 4449 belongs to a group of galaxies in the constellation Canes Venatici, ‘the Hunting Dogs’. Astronomers think that NGC 4449’s episode of star formation has been influenced by interactions with several of its neighbours. It is likely that the current widespread starburst was triggered by interaction or merger with a smaller companion.

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http://www.esa.int/esaSC/SEMD5ZI2O3F_index_0.html
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PostPosted: Tue Jul 31, 2007 11:15 am    Post subject: Veil Nebula Pierced by Hubble's Gaze Reply with quote

Veil Nebula Pierced by Hubble's Gaze
By Dave Mosher, Staff Writer

posted: 31 July 2007 11:55 am ET

Only 5,000 to 10,000 years ago, a star familiar to human observers detonated and burned with a brightness comparable to that of a crescent moon--an event visible even in broad daylight.

The dead star's name may be lost, but its shattered remains are known as the Veil Nebula or Witch's Broom Nebula. Now, the Hubble Space Telescope has given astronomers three extreme close-ups of the supernova remnants' wispy clouds of dust and gas still careening into space some 1,500 light-years away from Earth.

For the full article:

http://www.livescience.com/spa.....ebula.html
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PostPosted: Thu Aug 09, 2007 3:18 pm    Post subject: Astronomers Find New Star 'Family' Reply with quote

Astronomers Find New Star 'Family'
By SPACE.com staff

posted: 08 August 2007 04:43 pm ET

Astronomers have spotted a small group of young stellar "siblings" in a dusty stellar nursery 848 light-years away.

The finding, made using NASA's Spitzer Space Telescope, could reveal more clues about the formation of and interactions among cosmic families made up of hundreds of gravitationally bound stars.

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http://www.livescience.com/spa.....amily.html
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PostPosted: Wed Sep 12, 2007 1:45 pm    Post subject: Bizarre Parasitic Star Found Reply with quote

Bizarre Parasitic Star Found
By Ker Than, Staff Writer

posted: 12 September 2007 11:59 am ET

A dead, spinning star has been found feeding on its stellar companion, whittling it down to an object smaller than some planets.

"This object is merely the skeleton of a star," says study team member Craig Markwardt of NASA's Goddard Space Flight Center in Maryland. "The pulsar has eaten away the star's outer envelope, and all that remains is its helium-rich core."

Pulsars are the cores of burnt out "neutron" stars that spin hundreds of times per second, faster than a kitchen blender.

The system was discovered in early June when NASA's Swift and Rossi X-ray Timing Explorer (RXTE) satellites picked up an outburst of X-rays and gamma rays in the direction of the Milky Way galactic center in the constellation Sagittarius.

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http://www.livescience.com/spa.....bject.html
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PostPosted: Thu Sep 13, 2007 5:15 pm    Post subject: Explanation of Dark Matter Might Lie in Origin of Stars Reply with quote

Explanation of Dark Matter Might Lie in Origin of Stars
By Ker Than, Staff Writer

posted: 13 September 2007 02:00 pm ET

Some of the universe's first stars might still be lighting up their corners of the cosmos, new computer models suggest. And finding these stellar oldies could reveal something about the nature of dark matter.

Dark matter is a mysterious substance scientists think accounts for most of the mass in the universe but that is invisible to current instruments. Theorists figure that in the universe's infancy, dark matter served as a gravitational rallying point around which normal matter-hydrogen, helium and lithium-gathered. These gases coalesced into the first stars, bringing light to the universe and ending the short-lived cosmic dark ages.

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http://www.livescience.com/spa.....stars.html
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PostPosted: Fri Sep 14, 2007 2:30 pm    Post subject: Thousands of schoolchildren worldwide map night skies Reply with quote

National Center for Atmospheric Research/University Corporation for Atmospheric Research
13 September 2007

Thousands of schoolchildren worldwide map night skies


BOULDER--Schoolchildren, families, and citizen scientists around the world will gaze skyward after dark from October 1 to 15, looking for specific constellations and then sharing their observations through the Internet. The initiative, called the Great World Wide Star Count, will help scientists map light pollution globally while educating participants about the stars.

The event, which is free and open to everyone who wants to participate, is organized by the Windows to the Universe project at the University Corporation for Atmospheric Research (UCAR), in conjunction with planetariums and scientific societies across the country and abroad. Funding is provided by the National Science Foundation.

"This is an important event that brings families together to enjoy the night skies and become involved in science," says Dennis Ward of UCAR's Office of Education and Outreach, who is one of the event coordinators. "It also raises awareness about the impact of artificial lighting on our ability to see the stars."

Participants in the Northern Hemisphere will look for the constellation Cygnus, while those in the Southern Hemisphere will look for Sagittarius. They will then match their observations with magnitude charts downloaded from the Great World Wide Star Count Web site (see below). The Web site also contains more information about the event, including instructions for finding the constellations, and it links to background about astronomy on the Windows to the Universe Web site.

Participants in overcast areas who cannot see stars will be able to input data about cloud conditions instead.

Thousands of observers in dozens of countries are expected to take part. Participants may make observations outside their homes or go to less developed areas where more stars are visible.

Bright outdoor lighting at night is a growing problem for astronomical observing programs around the world. By searching for the same constellations, participants in the Great World Wide Star Count will be able to compare their observations with what others see, giving them a sense of how star visibility varies from place to place. The observers will also learn more about the economic and geographic factors that control the light pollution in their communities and around the world.

"Without even being aware of it, many of us have lost the ability to see many stars at night," Ward says. "The Great World Wide Star Count will help raise awareness of the importance and the beauty of the night skies."


###
The University Corporation for Atmospheric Research is a consortium of 70 universities offering Ph.D.s in the atmospheric and related sciences. UCAR manages the National Center for Atmospheric Research (NCAR) and the UCAR Office of Programs (UOP).

On the Web:
Great World Wide Star Count http://www.windows.ucar.edu/starcount
Windows to the Universe http://www.windows.ucar.edu
Resources for Journalists: http://www.ucar.edu/news/journalists.jsp
Read this and past releases or sign up for e-mail delivery: http://www.ucar.edu/news/releases
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PostPosted: Sat Sep 22, 2007 9:47 am    Post subject: Behind the Scenes:Search is on for Hot Young Stars Reply with quote

Behind the Scenes:Search is on for Hot Young Stars
By Tiare Devenot, W. M. Keck Observatory

posted: 21 September 2007 01:18 pm ET

This Behind the Scenes article was provided to LiveScience in partnership with the National Science Foundation.

On average, at least three gamma-ray bursts occur somewhere in the heavens each day. Shri Kulkarni has trained his eyes up to these new wonders with his latest research in this emerging field.

Kulkarni’s studies focus on long duration gamma-ray bursts. These bursts occur when a young massive star burns through its hydrogen core.

For the full article:

http://www.livescience.com/spa....._rays.html
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PostPosted: Tue Oct 02, 2007 12:55 pm    Post subject: Reply with quote

NASA/ESA

Extreme star cluster bursts into life in new Hubble image

02-Oct-2007: The NASA/ESA Hubble Space Telescope has captured a spectacular image of NGC 3603, a giant nebula hosting one of the most prominent massive young clusters in the Milky Way, thus supplying a prime template for star formation studies.

For the full article:

http://www.spacetelescope.org/.....c0715.html

http://www.esa.int/esaSC/SEM7A87H07F_index_0.html
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PostPosted: Wed Oct 31, 2007 2:02 pm    Post subject: New Spin on How Stars are Born Reply with quote

New Spin on How Stars are Born
By Ker Than, Staff Writer

posted: 31 October 2007 02:01 pm ET

Invisible magnetic field lines twisted like long ropes of DNA help stars spiral into life, according to a new model.

New stars form from enormous clouds of gas and dust collapse under their own gravity into dense spheres. The packed cores are ignited by thermonuclear reactions. As they collapse, the clouds rotate, and like an ice skater pulling in his arms while spinning, rotation speed increases as the collapsing cloud gets smaller.

For the full article:

http://www.livescience.com/spa.....lapse.html
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PostPosted: Mon Nov 05, 2007 5:44 pm    Post subject: Setting stars reveal planetary secrets Reply with quote

Setting stars reveal planetary secrets
ESA

5 November 2007

Watching the stars set from the surface of the Earth may be a romantic pastime but when a spacecraft does it from orbit, it can reveal hidden details about a planet’s atmosphere.

The technique is known as stellar occultation. Jean-Loup Bertaux, Service d'Aeronomie du CNRS, France was the first to suggest its use on an ESA mission. It works by watching stars from space, while they drop behind the atmosphere of a planet under investigation, before disappearing from view below the planet’s horizon.

For the full article:

http://www.esa.int/esaCP/SEMEH3FWB8F_index_0.html
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PostPosted: Wed Nov 28, 2007 1:27 pm    Post subject: Chandra discovers cosmic cannonball Reply with quote

Chandra X-ray Center

Chandra discovers cosmic cannonball

28 November 2007

One of the fastest moving stars ever seen has been discovered with NASA's Chandra X-ray Observatory. This cosmic cannonball is challenging theories to explain its blistering speed.

Astronomers used Chandra to observe a neutron star, known as RX J0822-4300, over a period of about five years. During that span, three Chandra observations clearly show the neutron star moving away from the center of the Puppis A supernova remnant. This remnant is the stellar debris field created during the same explosion in which the neutron star was formed about 3700 years ago.

By combining how far it has moved across the sky with its distance from Earth, astronomers determined the neutron star is moving at over 3 million miles per hour. At this rate, RX J0822-4300 is destined to escape from the Milky Way after millions of years, even though it has only traveled about 20 light years so far.

"This star is moving at 3 million miles an hour, but it's so far away that the apparent motion we see in five years is less than the height of the numerals in the date on a penny, seen from the length of a football field," said Frank Winkler of Middlebury College in Vermont. "It's remarkable, and a real testament to the power of Chandra, that such a tiny motion can be measured."

"Just after it was born, this neutron star got a one-way ticket out of the Galaxy," said co-author Robert Petre of NASA's Goddard Space Flight Center in Greenbelt, Md. "Astronomers have seen other stars being flung out of the Milky Way, but few as fast as this."

So-called hypervelocity stars have been previously discovered shooting out of the Milky Way with speeds around one million miles per hour. One key difference between RX J0822-4300 and these other reported galactic escapees is the source of their speed. The hypervelocity stars are thought to have been ejected by interactions with the supermassive black hole in the Galaxy's center.

This neutron star, by contrast, was flung into motion by the supernova that created Puppis A. The data suggest the explosion was lop-sided, kicking the neutron star in one direction and the debris from the explosion in the other.

The supernova was precipitated when the core of a massive star imploded to form a neutron star. Computer simulations show that the infall of the outer layers of the star onto a neutron star releases an enormous amount of energy. As this energy propagates outward, it can reverse the infall and eject the outer layers of the star at speeds of millions of miles per hour. Due to the complexity of the flow, the ejection is not symmetric, leading to a rocket effect that propels the neutron star in the opposite direction.

The breakneck speed of the Puppis A neutron star, plus an apparent lack of pulsations from it, is not easily explained by even the most sophisticated supernova explosion models.

"The puzzle about this cosmic cannonball is how nature can make such a powerful cannon," said Winkler. "The high speed might be explained by an unusually energetic explosion, but the models are complicated and hard to apply to real explosions."


###
Other recent work on RX J0822-4300 was published by C.Y. Hui and Wolfgang Becker, both from the Max Planck Institute for Extraterrestrial Physics in Munich, in the journal Astronomy and Astrophysics in late 2006. Using two of the three Chandra observations reported in the Winkler paper and a different analysis technique, the Hui group found a speed for RX J0822-4300 that is about two-thirds as fast, but with larger reported margins of error.

The research by Winkler and Petre was published in the November 20 issue of The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.
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PostPosted: Sat Dec 01, 2007 12:30 pm    Post subject: Light Night, Dark Stars Reply with quote

Light Night, Dark Stars
Amanda Leigh Haag

Dec. 5, 2007

In early October, thousands of people around the globe stepped outside to gaze at their local night sky. As part of an event called the Great World Wide Star Count, adults and kids looked for one of two constellations—Cygnus in the Northern Hemisphere and Sagittarius in the Southern Hemisphere. The observers recorded how many stars they saw and how bright the stars were, and then posted their results online.

The Star Count was part of a global effort to help scientists learn more about how light pollution affects our view of the night sky. Whether participants saw thousands of stars—or just a dozen—depended a lot on whether they were surrounded by darkness or by twinkling city lights.

For the full article:

http://www.sciencenewsforkids......ature1.asp
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PostPosted: Mon Dec 03, 2007 2:23 pm    Post subject: Were the first stars dark? Reply with quote

University of Utah
2 December 2007

Were the first stars dark?
Study: Dark matter in newborn universe doused earliest stars

“Dark star crashes, pouring its light into ashes” – The Grateful Dead, 1967.


Dec. 3, 2007 – Perhaps the first stars in the newborn universe did not shine, but instead were invisible “dark stars” 400 to 200,000 times wider than the sun and powered by the annihilation of mysterious dark matter, a University of Utah study concludes.

The study – to be published next month in the journal Physical Review Letters – calculated how the birth of the first stars almost 13 billion years ago might have been influenced by the presence of dark matter – the unseen, yet-unidentified stuff that scientists believe makes up most matter in the universe.

The findings “drastically alter the current theoretical framework for the formation of the first stars,” says study author and astrophysicist Paolo Gondolo, associate professor of physics at the University of Utah.

It is conceivable that gigantic dark stars may exist today, and although they do not emit visible light, they could be detected because they should spew gamma rays, neutrinos and antimatter and be associated with clouds of cold, molecular hydrogen gas that normally wouldn’t harbor such energetic particles, he adds.

“Without detailed simulations, we cannot pinpoint the further evolution of dark stars,” Gondolo says. “They could last months. They could last 600 million years. Or they could last billions of years and still be around. We have to search for them.”

He conducted the study with astrophysicist Katherine Freese of the University of Michigan, Ann Arbor, and graduate student Douglas Spolyar of the University of California, Santa Cruz.

Gondolo says he wanted to call the new, theoretical kind of invisible star a “brown giant” – similar to the dim but smaller, Jupiter-sized stars known as “brown dwarfs.” But he says his co-authors insisted on calling them “dark stars,” after the song “Dark Star” first played in 1967 by the revered rock band The Grateful Dead.

“It’s catchier,” Gondolo acknowledges.

Dark Matter, the Big Bang and the First Stars

Gondolo says some studies have considered the role of dark matter in the evolution of the early universe, but until now, not in the formation of the first stars.

Scientists know dark matter exists because galaxies rotate faster than can be explained by the visible matter within them. Also, observations by satellites, balloons and telescopes have led to the estimate that all the visible matter represents only 4 percent of the universe, which also is made of 23 percent dark matter and 73 percent “dark energy” – a yet-unknown force helping the universe expand, Gondolo says.

WIMPS – or weakly interacting massive particles – are among the main candidates for dark matter. Gondolo says “neutralinos” are a type of WIMP that must exist under particle physics theories that seek to explain the origin of mass in the universe.

Scientists generally believe that the universe came into being 13 billion years ago in a sudden expansion or “inflation” of time and space known as the “big bang.”

The afterglow of that explosion – cosmic microwave background radiation – developed small fluctuations in temperature that caused some of the earliest matter to begin clumping together, a process accelerated by gravity and that produced the first stars and galaxies. The matter was mostly dark matter but also included normal matter in the form of hydrogen and helium gas.

The conventional theory of how the first stars were born holds that as hydrogen and helium atoms clumped and swirled together in proto-stellar clouds, they began to cool, making the cloud shrink and become denser. The cooling and shrinking of the embryonic star continues until the fusion of hydrogen into helium begins, igniting the fusion engine that burns in our sun and other stars.

How ‘Twinkle, Twinkle Little Star’ Got Snuffed

For the new study, the astrophysicists calculated how dark matter would have affected the temperature and density of gas that clumped together to form the first stars.

The findings suggest that dark matter neutralinos interacted so they “annihilated” each other, producing subatomic particles called quarks and their antimatter counterparts, antiquarks. That generated heat. As a proto-stellar cloud of hydrogen and helium tried to cool and shrink, the dark matter would keep it hot and large, preventing fusion from igniting the star.

“The heating can counteract the cooling, and so the star stops contracting for a while, forming a dark star,” some 80 million to 100 million years after the big bang, says Gondolo. “This is our main result.”

Dark stars would contain mostly normal matter – mostly in the form of hydrogen molecules and helium – but they would be vastly larger and “fluffier” than the sun and other stars, he adds. They would have glowed infrared, which is heat.

“They are much bigger than the sun,” Gondolo says, with diameters ranging from about 4 astronomical units (372 million miles, or four times the average distance between the sun and Earth) to 2,000 astronomical units – big enough to swallow 15,000 solar systems like our own.

The quarks and antiquarks produced within the dark star would, in turn, generate descendant particles including gamma rays, neutrinos and antimatter such as positrons and antiprotons, Gondolo says.

“With your bare eyes, you can’t see a dark star. But the radiation would fry you.”

Implications of Dark Stars

Gondolo says dark stars have some important implications for astrophysics:

-- They represent a new phase in the evolution of stars.

-- Their possible existence could aid the search to find and identify dark matter. Gamma rays, neutrinos and antimatter have characteristic energy signatures if they come from dark matter.

-- They could improve understanding of how heavy elements formed. The first stars supposedly were the cradle of elements as heavy or heavier than carbon, producing them via nuclear fusion. But if dark stars existed and did not later evolve into normal stars, they didn’t make carbon. “Maybe carbon came from other stars” – perhaps conventional stars that formed where there was no dark matter nearby, Gondolo says.

-- Dark stars may explain why black holes – collapsed stars so dense that not even light escapes – formed much faster than expected. Gondolo says black holes existed only a few hundred million years after the big bang, yet current theories say they took longer to form. “These dark stars may help. They could collapse into black holes very early because they are very short-lived and formed when the universe was young, at least in one scenario.”

Another possibility is that dark stars lasted quite a while but eventually turned into conventional stars. Gondolo and colleagues, however, argue the gas cooling and dark matter heating within a dark star can remain in balance, allowing dark stars to survive, but that depends on certain assumptions about the mass of neutralinos.

“We don’t know how long they last, so we speculate. It depends very sensitively on the parameters of the model.”


###
The study was funded by the National Science Foundation, U.S. Department of Energy and the University of Michigan.
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