By Jim Kaler

Department of Astronomy, University of Illinois

The New "Advances"

For two decades, I gave "Astronomy Update" talks to annual conference of the Great Lakes Planetarium Association, after which the lectures were written up for publication both in their Conference Proceedings and on the Web, the last one for 2008. After a hiatus of two years, this long-term project on astronomy news is continued here in written form only and with a different name, "Advances in Astronomy." The first of these covers the two year period, 2009-2010 (actually November 2008 - October 2009, consistent with the GLPA talks). Deep thanks go to past and potential readers, to GLPA, and to Dale Smith for scanning the updates for 1989 through 1994. I am also indebted to Sky and Telescope, Astronomy, the Hubble NewsCenter, and to numerous other sources.

Flying High ... and Low

IT'S BEEN SAID that there are only two telescopes, Galileo's and the Hubble with only improvements in between. We are going to have the latter for awhile, as at the top of this double-years' worth of news, the HST saw new life with a magnificent repair job and the installation of a new camera and imaging spectrograph. The great machine should be good for many more years of service.

But there ARE others. A brief rundown includes the Gamma Ray Large Area Telescope (GLAST, now the Fermi Gamma Ray Telescope), the Spitzer Space Telescope (having run out of coolant now in "warm phase"), and the Herschel infrared telescope (which has seen first light). Down on the ground is Pan-STARRS (the Panoramic Survey Telescope and Rapid Response System, whose 3-degree field will be used to image 1/5 of the sky every night to spot approaching asteroids and to detect ephemera, and the Auger Cosmic Ray Observatory, which will use the air to detect high-energy particles from space. In between, SOFIA (the Stratospheric Observatory for Infrared Astronomy built into a Boeing 747 aircraft) finally saw first light, and then back up into space is PLANCK, which is examining subtle fluctuations in the Cosmic Microwave Background radiation to probe the origins of the Universe. Meanwhile, looking back into EARTHLY past, the historic David Dunlap Observatory of the University of Toronto has been spared to become a public facility.

The Sun

Specific to our own star, we saw the launch and opening of the Solar Dynamics Observatory, which should re-define our knowledge of space weather and solar activity, much as SOHO did in the past. Maybe it will help tell us why the "sunspot desert" has continued in an extended solar minimum. When will the spots and activity return? Are we approaching a new Maunder Minimum and "little ice age?" We have made some progress in the idea that small numerous nanoflares are responsible for heating the two-million Kelvin corona. Just how they do that, though, remains a mystery.

In the solar subtlety category, the Sun is seen to have a tiny, 8-milliarcsecond equatorial bulge that goes to 11 at high activity, suggesting the bulge to be magnetic in origin. Second, new radar observations have refined the Astronomical Unit to 149,597,870.696 kilometers (accurate to 10 centimeters), and show that as a result of mutual tides, the Sun is getting farther away by 15 cm per year (which is not enough to offset global warming!).


You can't speak of the Sun without calling to the Moon. The BIG ISSUE of course is water, which now seems to be all over, though in minuscule amounts. It was seen in the LCross impact, which dredged up minimally "wet" debris from a dark, cold crater near the lunar south pole, by an Indian orbiter that found ice in north polar craters, and through various other studies that showed it locked as hydroxyl in surface minerals.

And, as already known, the Moon is OLD, a new study dating the solidification of small crystals to 4.42 billion years ago.

Little Planets

Finally, after a hugely long hiatus, Mercury is under intense scrutiny from MESSENGER, which has flown past the planet three times and is headed for orbit insertion. It's found the second largest basin in the solar system, 715 km across, and depressions in craters that appear to be volcanic calderas. Oddly, the planet has an internally-generated magnetic field rather like Earth's, implying a "dirty," hence partially molten, iron core.

Here, Venus Express does the job. Infrared observations of the surface reveal shield volcanoes topped with rock that is different from that down in the plains, suggesting that the volcanoes were recently active. Similar data from the southern hemisphere also points to different kinds of rock, including granite, that suggests both an ancient ocean and plate tectonics. Could the runaway greenhouse planet once have been more earthlike, and is there a lesson here?

Books of course could be written from the Rovers' adventures alone (which are in their seventh year, long past warranty), never even minding Mars Reconnaissance Orbiter and various other craft. "Sprite" got famously stuck, but "Opportunity" lumbers on.

Water seems to dominate the themes. Phoenix died, but found lots of buried ice in the far-northern plains, plus clays and salts. Farther north, the polar cap seems to have been carved in its curving forms by winds. Meanwhile, Mars Express found subsurface southern-hemisphere ice that evokes ancient glaciers. Surface mineralogy suggests an ancient ocean (as do long-known shorelines). Methane plumes intriguingly suggest (perhaps wishful) biological activity, but are more likely geological in origin.

Big Ones

Whacked again in 2009, an asteroid or comet impact left a southern-hemisphere scar thousands of kilometers wide, the colliding body thus several hundred meters across. Modelling shows that Jupiter's rocky-metallic core (though in form vastly unlike the rock we know) is larger than thought, its mass somewhere between 14 and 18 Earths.

With Cassini still in orbit, the data keep flooding in, so much that only a sample of discovery is possible. Like Earth and Jupiter, Saturn has a magnetically-induced aurora. But for no known reason, it's different. Rather than being ring-like, its infrared glow covers the whole pole. Lightning bolts strike 300 km long, while storms can last for months.

The focus seems to be more on the intriguing satellites, particularly on Titan, with its methane lakes and hydrologic cycle that causes the lake levels to go up and down in response to evaporation and rains. The amazingly satellite also seems to have watery volcanoes. Meanwhile the famed geysers of Enceladus are apparently caused by heat produced by a tidal resonance with Dione, the debris feeding the E ring. The continuing geysers plus salts in the E Ring point to a possible liquid water ocean beneath the moon's rocky surface. Is it yet, along with Jupiter's Europa, another site for life?

Satellite-ring interactions continue with the 61st-known moon feeding the G ring (which lies just past the A ring), and with backwards-orbiting Phoebe (which probably is a captured Kuiper Belt Object) creating a newly-found (from Spitzer) giant tilted outer dust ring. Iapetus then sweeps up the dust on one hemisphere to give it its two-sided nature. Various embedded moonlets disturb ring particles to help create the rings' structures.

Finally, start the party. Neptune will complete one full orbit since discovery on July 12, 2011.

Really Small Stuff: Asteroids, Comets, and KBOs

Huge numbers: asteroids with known orbits around half a million. And the total number there are now has but a thousandth the original mass thanks to gravitational scattering by the planets. They may have been born large and then have ground themselves down through collisions that are still going on. Indeed, we seem to have witnessed the aftermath of a direct hit of one on another, which created a streaming dust tail with an unexplained X-shaped head.

They of course hit us as well, asteroid 2008 TC3 was observed before it burst in the air over the African Sudan. Three- hundred-meter-wide Apophis, though, will not, at least not soon, but it is expected to pass close enough to reach easily-visible third magnitude in April of 2029. It ought to present quite a sight.

Turning the tables, we continue to visit them. The Rosetta spacecraft visited both three-mile-wide asteroid 2867 Steins and larger (100 X 131 km) 21 Lutetia (both of which are badly beaten up) on its way to land on Comet 67P in 2014. Sadly, Hyabusa returned from asteroid 25143 Itakawa with no known samples (though the craft is being examined for traces).

Comets are another matter. The Deep Impact strike revealed amorphous ice. Disintegrations of short-period comets seem to be responsible for the Zodiacal light, which makes sense since they come from the trans-Neptune Kuiper Belt and strongly tend to stick to the ecliptic. In the most exciting of findings, the STARDUST mission seems to have uncovered the amino acid glycine, a building-block of life, in Comet Wild 2. Since early comet impacts s are thought to have brought our water, they have supplied a rich pre-biotic chemistry as well.

But not all Kuiper Belt Objects (KBOs) are regular. At least one (like Halley's Comet, which is not a KBO) orbits retrograde. They confuse further. A stellar occultation of another showed it to be smaller than expected, and thus bright, in violation of the expectation that such objects are covered with dark chemicals. "Retired planet" Pluto is the most famed of the KBOs. Exquisitely-processed HST observations reveal a changing, variegated surface with methane-nitrogen frosts as the atmosphere freezes out, combined with dark areas in which methane has been processed into dark carbon compounds. We avidly anticipate New Horizons' visit in 2015.


More books could be written about extrasolar planets. And are. All we can do is sample the discoveries to give flavor to the subject. We passed 400 of them, the number increasing with great rapidity. Kepler (the transit-finding spacecraft) alone quickly found some 700 candidates, the number destined to rise fast. At least one- third, maybe a half, of all stars may have planets, the percentage apparently going up with stellar mass. While planet- holding stars tend to be more metal-rich than those without, they are notably lithium-poor, the possible result of downward circulation of the element where it is destroyed by high interior heat, possibly as a result of stellar rotation spun up by the planets.

While most planets are discovered through the Doppler effect, we now have finally SEEN them orbiting Fomalhaut (one Jupiter-like planet in a 115 AU orbit), HR 8799 Pegasi (three "Jupiters" within a few dozen AU), and famed Beta Pictoris (one "Jupiter" in which we have seen orbital motion, which is consistent with Beta Pic's beautiful large dusty disk).

Equally big news is the discovery of lower mass bodies that approach Earth in mass and size. Gliese 581 sets the current record. A red (class M) dwarf 20 light years away, Gl 581 is orbited by at least four planets (and maybe as many as six) that range from around 2.5 Earth masses to perhaps half a Neptune mass. The little one, Gl 581e, is in a 3-day, 0.03 AU orbit. More massive (but still rather earthlike) Gl 581d circles close to the habitable temperature zone of the dim star -- if that means much.

Other highlights include 61 Virginis with three "superearths," GJ 1214b, a low density superearth "water world" (or some such), a huge eccentric (e = 0.93) jupiter going around HD 80806, backward orbits, non- coplanar orbits (Upsilon Andromedae), planets that interact with each other (24 Sextantis), which may explain such systems as Ups And, and more, showing that our more or less regular Solar System is hardly the paradigm we thought it would be.

Add to these, nearby planet-holding Epsilon Eridani, which appears to have two infrared-radiating "asteroid belts, one 3 AU out, another at 20, all within an outer disk at around 100. The planet is associated with the inner belt, suggesting that the other two belts might hold more.

Brown Dwarfs

It's just a step up (from planets) or, if you like, down (from stars) to the brown dwarfs. Faint VB 10 near the bottom of the main sequence provides a transition as the lowest mass star known to have a planet, one near the brown dwarf cutoff around 0.08 of a solar mass, below which full core hydrogen- burning is not possible.

And there are not as many brown dwarfs as once believed. As we drop in mass along the main sequence of the HR diagram, stars become more numerous. But instead of steadily increasing all the way down, their numbers seem to turn over and reverse somewhere in late (cool) class M. Among the cooler set is a puzzling eclipsing double brown dwarf in Orion in which the larger is the cooler rather than the warmer, which is explained by having the larger covered with starspots, which in turn goes along with some brown dwarfs being magnetically active flare stars (for which there is little explanation). Among them too is the coolest class T brown dwarf, just 620 Kelvin, not much warmer than your baking oven. It may be a transition object into still-empty class Y.


Real stars are hardly neglected. It seems that Alcor has an M dwarf companion about a second of arc away. Given that Mizar is already quadruple (each of the stars of the visual double also a pair), the Mizar-Alcor system is now known to be sextuple both similar to, yet very different from, Castor. Moving up in mass, Spica, a close "ellipsoidal binary" that varies as a result of tidally distorted stars baring different cross sections as they orbit, does indeed seem to very slightly eclipse. Moving up farther, satellite infrared observations show that Betelgeuse is producing a shock wave as it plows through an interstellar cloud at 30 km/s, double the speed of its wind. The star is violently convective, non- spherical, irregularly losing mass at a rate of some five hundred thousandths of a solar mass a year, and for now getting smaller, the diameter down by 15 percent between 1993 and 2010. Given its known long-term behavior, the trend will probably eventually reverse.

Staying big, the strangeness of Epsilon Aurigae nears a final explanation. Every 27 years, the readily visible class F supergiant (one of Auriga's "Kids"), comparable to the Earth's orbit in size, is eclipsed for an amazing two years as a giant disk of dust some 10 AU in diameter surrounding an accreting B star passes in front of it, cutting the total light by 0.8 magnitudes. The last eclipse began in August of 2009, and will go on until May of 2011. Go watch.

And going up more, Eta Carinae (which in the 19th century erupted to become the second brightest star in the sky) is brightening again, and is now up to magnitude 4.7. Is it returning to normal, or preparing to erupt again?

And at the peak of the pile, THEY'RE BACK. Supermassive stars. Models show one of 170 solar masses (topping the supposed upper limit of 120 Suns) in NGC 3603, another in the Tarantula Nebula complex (R 136a1) of 320 suns. But watch out, as the history of the subject says no. Near the bottom end, the Kepler satellite found an eclipsing pair of low mass white dwarfs, each (from their sizes) about 0.2 solar masses, far lower than seemingly possible, suggesting once-strong mass loss.

A handful of "hypervelocity stars" have been flung out of the Galaxy compliments of the gravitational action (so thought) of the central supermassive black hole. A record of 817 km/s relative to the Sun (55 times normal for local disk stars) seems to have been originated by a triple, when the black hole absorbed a distant companion to a close inner double that then got tossed out and subsequently merged to become a class B "blue straggler," a star that is too massive and unevolved for its supposed age.


Clusters of stars, that is, of the globular persuasion. The first gamma rays have been found coming from a globular cluster, from massive 47 Tucanae. They may be have their origins in the cluster's set of millisecond pulsars.

And just what are these clusters anyway? Terzan 5 joins giant Omega Centauri as a possible stripped dwarf galaxy that merged with ours, the evidence lying in two distinct generations of stars. It's also suspected that a quarter of all globulars actually came to us from galaxy mergers, including Messier 80 -- which is what M 54 is doing now as it arrives compliments of the Sagittarius dwarf.

Supernovae, Pulsars, and Stellar Black Holes

Light echoes, which were wonderfully visible in creating various phenomena around Supernova 1987a, are becoming a powerful observing tool for probing historical SN. The spectrum of a 436-year-old echo off an interstellar dust cloud confirmed that Tycho's Star was a normal Type Ia supernova (produced by a white dwarf in a binary system that accreted more mass from its companion than it could support). Multiple echoes from 330- year-old Cassiopeia A also allowed a three-dimensional reconstruction that shows an asymmetric blast, the central pulsar (neutron star) going off at 350 km/s opposite a jet.

The remnant pulsar is essentially the progenitor star's old iron core that has been compressed into neutrons. X-ray observations yield an expected diameter of 30 or so kilometers only if Tycho's pulsar/neutron star has a carbon atmosphere, the result of nuclear "burning" of helium, which in turn came from hydrogen. The Sun's "atmosphere," from which its radiation is emitted, is a thousand kilometers deep. The gravitational force at the surface of a neutron star is so great that the carbon layer is squeezed to a depth of only 10 centimeters! Or so goes the theory.

New, energetic pulsars like the one in the Crab Nebula radiate across the spectrum, while spun-down old ones emit only radio. It came as a surprise then when Fermi/GLAST (see the note at the top) discovered that a handful of pulsars radiate ONLY gamma rays. Apparently, the cone with which they sweep the sky is wider for gamma rays than it is for optical or radio, and if we are on the edge, we get just the gammas.

Astronomers keep anticipating a wider variety of exploding stars. Among the theoretically expected are "pair-instability" supernovae. In these, the stars are so massive that highly energetic gamma ray collisions in the deep interiors create electron/positron pairs that causes sudden cooling and thus collapse. A superenergtic blast from ultradistant SN 2007bi suggests it might be a long-searched-for example that came from the collapse of a 100-solar-mass helium core. But we do not yet have a definitive answer.

Normal supernovae, though, still have the standard two routes to success, collapse of an iron core (Type II, Ib, Ic) or a white dwarf that are pushed beyond the "Chandrasekhar Limit" of 1.4 solar masses (Type Ia). The latter have two sub-routes, overflow from a binary companion or merger of the stars in a double white dwarf, which could produce mergers far beyond the limit and super-luminous Type Ia's, which in turn would confuse the Universe's distance scale, for which Ia SN are standard candles because of their uniformity. SN 2007if might have been an example.

Pulsars have varieties too that include millisecond versions that are spun up by accretion from a companion, and magnetars that have fields 100 times that of a normal pulsar and that are visible in the gamma ray and X-ray spectral domains. Surface adjustments of the magnetars can radiate so intensely that they effect the Earth even from thousands of light years away. Now the first optical/infrared magnetar has been found, studies of which will help untangle their mystery.

The Galaxy

That is, OUR Galaxy. It has a well-studied supermassive black hole at its center that lies some 27,000 light years away from us. Only 0.3 Astronomical Units across, less than the size of Mercury's orbit, from motions and orbits of surrounding stars its mass has been refined to 4.3 million times that of the Sun. Oddly, in spite of its disruptive nature, star formation still goes on only 10 or so light year away from it.

Moving on out, studies of radio radiation from star-forming regions suggest that the Sun is orbiting the Galaxy fifteen percent faster (at 255 kilometers per second) than once thought, which boosts the Galactic mass upward by 35 percent or more.


For which there is another hodge-podge of various discoveries. Our Galaxy is filled with high-speed particles, cosmic rays accelerated to near the speed of light by supernova shock waves. They constantly hammer into Earth, produce carbon-14, and possibly even initiate lightning and rain. If you think it is violent here, try Messier 82, a "starburst" galaxy in which the supernova rate is so high that the whole galaxy was once thought to be exploding. The resultant cosmic ray flux is 500 times what we have here, which, speculating, might make life near- impossible.

When we look outward, we also look back in time. This effect matters not for stars and nearby galaxies, but at the extreme, it allows us to see distant galaxies and the far reaches of the Universe as they once were. There is thus a constant search for the "youngest galaxy," that is, the most distant. We are down to 600 million years after the Big Bang, showing that galaxies formed VERY fast indeed. The most distant cluster of galaxies has been moved back to 9.5 to 10 billion light years away.

All more or less local galaxies, though, are expected to be about the same age. Since their metal content comes from stellar evolutionary processes, large galaxies have higher metallicities than low-mass ones. It comes as a surprise then to find large galaxies with low metals. Either galaxies can form late, well after the Big Bang, or, more likely, the effect is due to mergers of smaller galaxies into the low-metal big ones we now see.

All large, even some small, galaxies seem to be organized about a central supermassive black hole of the sort that occupies our own central region, many far more massive than ours, topping out in the low billions of solar masses. There is a growing consensus that the black holes came first and that the galaxies subsequently organized around them. That the masses of central bulges of galaxies are tied to the mass of the central black hole (in a local 700-to-1 ratio) suggests that the latter limits the former by blowing away potentially accreting matter. Moreover, very young, distant galaxies show a bulge-to-black-hole ratio of only 300:1, suggesting continued and later galaxy growth.

Lying at the cores of faint young galaxies, quasars are the youngest, most distant, and most wildly active of the supermassive black holes, from which pour vast amounts of energy and flows of matter in the form of jets. Occasionally, we find double black holes at the centers of galaxies as a result of galactic mergers, nearly three dozen now known. At the extreme is a double quasar in which the individuals, only 0.3 light years apart, orbit in a mere century and are probably destined to merge. In one case, a merger was apparently so violent that it seems to have actually ejected the black hole from the galaxy's center.

Gamma Ray Bursts

At the fringe of the Universe, the most distant galaxies contain the most violent of supernovae, "hypernovae" from very massive stars that radiate massive bursts of gamma rays, which in turn produce optical afterglows that can be so bright as to be visible to the naked eye. The highest confirmed red shift is in the neighborhood of 8.2, the instigator just over 600 million years old and some 13 billion light years away. A GRB may result from intense magnetic fields generated in the stellar collapse that produces the hypernova.

We are getting close to the era of the zero-metal "Population III" stars that were formed from only the hydrogen and helium that came from the Big Bang, their ages expected to be in the range of 200-400 million years (the time after the Bang itself).

Dark matter, Dark Energy, and Everything Else

We still of course do not know what dark matter and energy are in spite of the DM mystery being with us since the 1930s. Is DM made of exotic particles? Are there viable alternative theories of gravity that explain them? Whatever they may be, dark matter exceeds the normal stuff in galaxies by a factor of 5 or so, and seems to love dwarf galaxies more than large ones, as the smaller galaxies have relatively up to 20 times more. Theory suggests that the small ones lost a lot of normal matter through supernova explosions, which do not affect the DM, and which helps protect smaller systems against gravitational shredding by larger ones.

Not to be left out, dark energy makes its mark locally as well, seeming to become significant by the time we reach the outer edge of the Local Group, our own small cluster of galaxies. Whatever it is, it seems to be an inherent property of space.

At the end, the seven-year WMAP (Wilkinson Microwave Explorer) results are in, which give an age to the Universe of 13.75 billion years (since the Big Bang), a Hubble constant of 70.4 kilometers per second per Megaparsec, the Universe "flat," Euclidean, and closed to within 0.23 percent. The mass-energy mix that achieves such flatness is made of 73 percent dark energy, 22 percent dark matter, and just five percent normal matter. Of the last, a mere half percent is in stars, leaving 3.5 percent or so (the numbers all subject to minor change) presumed to be in hot intergalactic gas, some of which was observed, but the rest actually missing. It's just been found as the cooler WHIM (the "warm-hot intergalactic medium"), leaving our story satisfyingly complete. If only we knew what makes some 95 percent of it all. Whatever it all is, without it we undoubtedly would not be here.