Tag: astronomy

The variability of stars according to Kepler

10:02 am

More data from Kepler! In a paper [pdf] published today on the astro-ph website, scientists outline Kepler’s census of the variability of stars. Key quote from the abstract:

We have separated the sample in 129,000 dwarfs and 17,000 giants, and further sub-divided, the luminosity classes into temperature bins corresponding approximately to the spectral classes A, F, G, K, and M. G-dwarfs are found to be the most stable with < 20% being variable. The variability fraction increases to 30% for the K dwarfs, 40% for the M and F dwarfs, and 70% for the A-dwarfs. At the precision of Kepler, > 95% of K and G giants are variable.

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Amateur detection of Jupiter impact

9:52 am

The detection in June by two different amateur astronomers of an impact on Jupiter bodes well for asteroid/comet research. You can read the actual paper here. [pdf] Key quote from the abstract:

A systematic study of the impact rate and size of these bolides can enable an empirical determination of the flux of meteoroids in Jupiter with implications for the populations of small bodies in the outer Solar System and may allow a better quantification of the threat of impacting bodies to Earth. The serendipitous recording of this optical flash opens a new window in the observation of Jupiter with small telescopes.

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As imagined by SF authors: the Celestial Spiral

2:30 pm

This amazing Hubble image, showing a strange spiral to the left of the bright star, is not of a galaxy. Instead, it is a binary star system where the material from one star is being sucked away from it by the other, thus producing the spiral pattern.

celestial spiral

What is most fascinating about this discovery is that this kind of phenomenon has been predicted for decades, by both astronomers and science fiction writers. Consider for example this quote from Larry Niven from his short story, The Soft Weapon, where he describes what he thinks the binary star Beta Lyrae might look like:

There was smoke across the sky, a trail of red smoke wound in a tight spiral coil. At the center of the coil was the source of the fire: a double star. One member was violet-white, a flame to brand holes in a human retina, its force held in check by the polarized window. The companion was small and yellow. They seemed to burn inches apart, so close that their masses had pulled them both into flattened eggs, so close that a red belt of lesser flame looped around them to link their bulging equators togehter. The belt was hydrogen, still mating in fusion fire, pulled loose from the stellar surfaces by two gravitional wells in conflict.

The gravity did more than that. It sent a loose end of the red belt flailing away, away and out in a burning Maypole spiral that expanded and dimmed as it rose toward interstellar space, until it turned from flame-red to smoke-red, bracketing the sky and painting a spiral path of stars deep red across half the universe.

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New exoplanets

11:24 pm

Exoplanet news! Scientists today announced the discovery of a host of planets, all orbiting a single star similar to the Sun. Though five are Neptune-sized, a sixth (not yet confirmed) might be the size of Earth. What makes this even more exciting is that the astronomers made the discovery using a ground-based telescope.

But wait, there’s more! Thursday NASA will hold a press conference about a new discovery by Kepler!

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Not a black hole?

6:04 am

European scientists, using the Very Large Telescope at the European Southern Observatory, have determined that a magnetar (a neutron star pulsar with an extremely strong magnetic field) was formed from a star with a mass 40 times that of the Sun. This is a significant discovery, as most theories say that any star this heavy should instead become a black hole when it dies. That this particular star instead became a neutron star challenges present astronomical theory.

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Astronomers announce their recommendations for the next decade

11:07 am

After two years of discussion among hundreds of astronomers, the committee for the 2010 Decadal Surveyn for Astronomy and Astrophysics announced its recommendations today. The two main recommendations were

The report also called for the federal government to become a partner in one of the two giant ground-based optical telescopes now in the planning stages. In addition, the report recommended that the government increase its participation in the Laser Interferometer Space Antenna (LISA), a space telescope designed to detect gravity waves, as well as commit monies to begin the design work for a new high resolution X-ray space telescope. Other recommendations including asking NASA to increase its support for medium-sized space telescopes.

The report did not recommend any replacement for the Hubble Space Telescope.

This report follows earlier decadal surveys, for the 1970s, 1980s, 1990s, and 2000s, all of which had enormous influence on what federal agencies and astronomers built over the following decade. For example, these decadal surveys recommended the construction of the VLA, the Chandra X-Ray Observatory, the Spitzer Space Telescope, and a host of other telescopes, all of which were built.

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Is it a planet or not?

5:50 pm

An object, initially announced in 1998 to be the first planet ever photographed, then rejected as a planet when data suggested it was too hot, is now being resurrected as a possible planet. Key quote by Adam Burrows of Princeton University:

[If true] this would punctuate one of the strangest episodes in the history of the emerging field of exoplanet research. If false, it would be one more warning that numerous pitfalls await the intrepid astronomer in search of planetary gold beyond the solar system.

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Diversifying your research portfolio

9:53 am

In this paper [pdf] adapted from a lecture he gave at an astronomy conference, Harvard researcher Abraham Loeb warns young scientists that their tendency today to take on safe research projects is unwise. Moreover, he notes the increasing “herd mentality” due to “stronger social pressure”, “more competition in the job market,” and the “growing fraction of observational and theoretical projects . . . done in large groups with rigid research agendas and tight schedules.” Key quote:

It is always prudent to allocate some limited resources to innovative ideas beyond any dogmatic “mainstream,” because even if only one out of a million such ideas bears fruit, it could transform our view of reality and justify the entire effort. This lesson is surprisingly unpopular in the current culture of funding agencies like NSF or NASA, which promote research with predictable and safe goals.

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Hubble image of face-on galaxy

10:10 pm

Another spectacular Hubble Space Telescope image was released today, showing a face-on spiral galaxy in the Coma cluster, located about 320 million light years away. Key quote:

The galaxy, known as NGC 4911, contains rich lanes of dust and gas near its center. These are silhouetted against glowing newborn star clusters and iridescent pink clouds of hydrogen, the existence of which indicates ongoing star formation. Hubble has also captured the outer spiral arms of NGC 4911, along with thousands of other galaxies of varying sizes.

NGC 4911

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The Sun’s oxygen content does match the galaxy’s

9:47 am

A preprint paper [pdf] published today on the Los Alamos astro-ph website has found evidence that the oxygen and neon content of our Sun matches the abundances found in the galaxy. This result is important in that previous research has suggested that the Sun’s oxygen abundance was significantly higher than the rest of the galaxy, a possibility that not only caused problems for the theorists but raised interesting questions about the uniqueness of our solar system.

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A ground-based telescope matches the Hubble Space Telescope-NOT

6:01 am

Correction.Regular reader James Fincannon emailed me to say that he thinks the image below is an artist’s impression. He is correct. I should have looked more closely at the press release. In reading the actual research paper [pdf] on the results it seems that the VLT did some very sophisticated spectroscopy, thereby measuring the uneven distribution of the velocity and density of the gas around the star. The image below was then created, based largely on Hubble images combined with the new data. In other words, this ground-based telescope did not match the abilities of a space-based telescope in any way. Had the Hubble images not existed the astronomers would have struggled to interpret their spectroscopic data.

Some important astronomy news: The European Southern Observatory’s Very Large Telescope (VLT) has released this spectacular image of supernova 1987a, the first and so far only supernova visible to the naked eye since the invention of the telescope.

SN1987a

This image is important for two reasons. First, The data shows that the supernova explosion was not symmetrical, with more material being thrown outward in some directions than in others. This fact confirms what astronomers in recent years have increasingly come to believe: Supernovae explosions are not simple spherical bursts, but chaotic events ripping stars apart in a lopsided manner.

Second, this image demonstrates that ground-based telescopes are becoming amazingly good at doing what the Hubble Space Telescope has done routinely for the past two decades. Five years ago, no telescope on the ground could have resolved the inner ring of supernova 1987a. Only Hubble in space had that capability. Now, VLT can do it, almost as well as Hubble. Though a space-based telescope can still beat any ground-based telescope, it is great news that the technology for ground-based telescopes has improved so much, especially since there presently are no plans to replace Hubble.

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Kepler finds more than 100 Earthlike planets

12:51 pm

In its first six weeks of observation, the Kepler mission apparently found almost 150 planets similar in size to the Earth. The results, learned by accident because a talk given by one of the co-investigators was posted on the web, have not yet been officially announced because the project scientists feel a need for additional time to confirm them. Many of these so-called planets might turn out to be false positives, so some caution is in order.

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Swallowing a planet

9:39 am

A star with an appetite: Astronomers have used the Chandra X-Ray Observatory to take a closer look at an engimatic star in the constellation Pisces and found that the dust cloud that surrounds it as well as the unusual and enormous jets that shoot from it probably originated when the star evolved, expanded, and swallowed an orbiting companion, either a giant planet or companion star.

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very big stars

11:20 am

Using the Very Large Telescope in Chile, astronomers have identifed a number of stars with masses thought to range from 150 to as much as 300 times the mass of our Sun. Fun quote from the press release:

Within [star cluster] R136, only four stars weighed more than 150 solar masses at birth, yet they account for nearly half of the wind and radiation power of the entire cluster, comprising approximately 100 000 stars in total.

Stars this gigantic are believed to end their life in an explosion so intense it destroys the star entirely, leaving nothing behind but an expanding debris cloud, from which other stars and planets (and even life) can form.

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Metals in the inner galaxy

9:11 am

A preprint paper, published today on the astro-ph website but also accepted for publication in the journal Astronomy & Astrophysics, has confirmed what scientists have suspected about the dust and gas between the stars: As you travel closer to the center of the Milky Way galaxy this interstellar medium gets increasingly enriched with heavy elements. The scientists believe this is because the higher rate of supernovae in the inner galaxy sprays space with more of these atoms.

Since the field of extrasolar planets has also found that the more heavy elements a star contains, the more chance it will have planets, the new results above suggest that we will find more planets as we look inward towards the galactic center.

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Water found around carbon star; Bok globule

9:31 am

Water vapor detected in deep space, first near the carbon star V Cygni and second in two dark starless cores. The second detection is a first time water has been seen in these black clouds. Fun quote from the abstract of the first paper notes how the detection “raises the intriguing possibility that the observed water is produced by the vapourisation of orbiting comets or dwarf planets.”

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