astro
catdynamics | January 11, 2011assorted bits of stuff from AAS, or that I was reminded of at the meeting
Astro Better - interesting blog/wiki/tweetnode
I'd noticed them before, mostly because they assimilated the Astro Rumour Mill, but hadn't really taken in what they were doing till I saw their AAS poster on monday
Wish they'd frontpage the Rumour Mill - have to dig down a bit to find it
Scott Ransom delivered a very good Warner Prize lecture, it was the first time I had heard Time correctly described as a Helix of Something Sparkly or Another...
Sloan Survey has put out Data Release 8, with a mega mosaic image:…
catdynamics | January 11, 2011Kepler announces discovery of transiting hierarchical triple.
Extremely weird, with bonus cute animation...
KOI-126 is an interesting object.
It is a massive star (F main sequence if I caught the numbers right) primary, with two low mass M-stars orbiting it.
The M-stars orbit each other in a very tight orbit, and their center of mass in turn orbits the primary, with both secondaries transiting the primary, providing very complex and fascinating light curves.
Exquisite.
No idea how such a system could come to be.
It is very compact, could even have planets further out, and very hard to see how…
catdynamics | January 10, 2011Kepler 10-b, announced at the Annual meeting of the American Astronomical Society today, has a mass of 4.6 Earth masses and a radius of 1.4 Earth radii. Density of 8.8
Kepler 10b: Exoplanet Catalog
Kepler Mission website - 700 more to go.
Kepler 10b - Mission catalog data
20 hour orbital period around an old, slightly metal poor ( Z ~ -0.15) G dwarf.
500 light years away.
Kepler 10b - artist's conception
Paper is Batalha et al (ApJ in press) - expect it will be on arXiv tonight.
Lightcurve ought to be interesting, will really tell us how deep Kepler is going to go.
11th magnitude host star,…
catdynamics | January 10, 2011The AAS is off to a good start:
Reines et al have found a good supermassive black hole candidate in Henize 2-10 - an irregular bulgeless dwarf galaxy about 10 Mpc away.
A dwarf irregular, with a diameter of only about 1 kpc, Henize 2 is in starburst. It contains a number of
massive, very young super star clusters.
SMBH are seen in almost every galaxy and, in the local universe, are correlated with the galactic bulge mass.
One of the open issues is which came first, the black hole or the galaxy.
Henize is bulgeless, and if it genuinely has a real SMBH, that would strongly hint that the black…
catdynamics | December 8, 2010The Zooniverse folks, hosts of the Galaxy Zoo project and other great astronomical crowd sourcing projects, has a new toy for folks to play with:The Milky Way Project
The Milky Way project take Spitzer data and asks you to draw circles on it - using the rather superb pattern finding power of your brain to find structures not obvious in the data.
Then there is science done.
The Galaxy Zoo has lead to some interesting new discoveries, like the Green Peas, and the Milky Way project ought to lead to more and different interesting stuff.
Have at it!
catdynamics | December 7, 2010From Earth to the Universe was a brilliant outreach project for the 2009 International Year of Astronomy, displaying online, and in real life, some of the best astronomical images around.
Now we have the Year of the Solar System coming up, who knew, and more and better images are needed!
From Earth to the Solar System
FETTSS will be an online collection of images that can be freely downloaded and exhibited by organizations worldwide in whatever manner they choose.
In celebration of NASA's Year of the Solar System, the images will showcase the excitement and discoveries of planetary…
catdynamics | November 18, 2010The discovery of a jovian mass planet around a metal poor horizontal branch star in a kinematic stream of stars, possibly originating from a merger with a dwarf galaxy, is an interesting conundrum.
With bonus updates and links.
HIP 13044 - 10' field generated from SIMBAD using Aladin
HIP 13044 is a 10th magnitude, F2 horizontal branch star.
It is about 600 700 pc away, has high proper motion and is associated with a tidal stream, and may therefore have originated in a dwarf galaxy that merged with the Milky Way a long time ago.
stellar tidal stream in Milky Way model
tidal stream…
catdynamics | November 11, 2010Do you know how many theoretical astrophysics tenure track positions there are each year?
About 5.
I am also interested in string theory...
catdynamics | November 11, 2010
Something went wrong with the GRE test in october.
Again.
Here is the official word from ETS
The GRE test administered in China, on Oct 23rd, was an old test.
GRE is offering free retakes next week or reimbursment.
This will seriously mess up grad school applicants from China, and not at a good time, with a lot of universities worried about funding and overcommittment on grad students recruitment (although I should note that some universities are taking opportunity and ramping up recruitment, for now, or deciding to gamble and plan on the funding situation improving).
So... is this a minor…
catdynamics | October 28, 2010Same old thing as yesterday...
Seriously, wtf is going on with the Sun?
click to embiggen
phew.
ok, so there are some, finally, like 4
upturn into the new cycle has started, bit late and slow
click to embiggen
definitely reminiscent of the late 19th C
click to embiggen
new prediction for the cycle amplitude is low and interesting
Belgians are still the definitive authority on the subject
need to figure this magnetic cycling thing out, getting to be annoying
catdynamics | October 27, 2010There is a beautiful pulsar paper coming out in Nature tomorrow, 28th of October issue (Demorest et al 467, 1081, 2010)
Green Bank Telescope measurements of PSR J1614-2230 show it to be a 3ms binary pulsar with a white dwarf companion in an orbit aligned near perfectly edge on to our line of sight.
Measurements of the Shapiro Delay provide a measurement of the mass of the white dwarf, allowing the mass of the neutron star to be calculated from the known orbit of the white dwarf.
The resultant inferred mass is 1.97 +/- 0.04 solar masses.
click to embiggen
This is a very nice result.
There…
catdynamics | October 15, 2010More reports from the IAU meeting at Torino, this time on surprises with the putative planet around Fomalhaut.
The IAU Symposium 276 comes to a close in Torino with a late surprise.
Ray Jay reports again, using the fanciest of modern technology, that something may be awry with the planet around Fomalhaut.
Fomalhaut b is the direct imagined planet with the dust ring: two epoch imaging showed a small dot which moved in a manner consistent with an orbit out at that radius.
The dot was a bit too bright, which led to speculation that it might be a ringed planet, like Saturn.
Well, Ray Jay reports…
catdynamics | October 12, 2010Canadian-French Hawaii Telescope transit observations show super-earth is probably a mini-neptune
Ray Jay reports from Torino that his group has CFHT observations on GJ 1214b transits, suggesting it has a H/He atmosphere, and is therefore probably not a "super-earth", but more likely an ice giant with neptune like atmosphere.
This is interesting, suggesting indirectly the planet migrated from beyond the ice line and did some gas accretion onto its core before reaching the inner system.
Looking forward to seeing the paper.
catdynamics | October 11, 2010There are reports from Torino about HARPS observations of Gliese 581(g)
Vogt et al reported on additional possible planets in the multi-planet low mass Gliese 581(g) system.
In particular they showed a ~ 3 sigma detection of a possible 3+ earth mass planet in a circular orbit with an orbital period consistent with a temperate surface.
The paper used a combination of historic Keck data, published HARPS data up through 2008 and new high cadence Keck data.
There was some concern when the paper came out that the False Alarm Probability was underestimated (see Cumming et al for discussion of…
catdynamics | October 4, 2010Many years ago, as I was writing up my thesis, my advisor burst into my office with the hot news.
Someone had announced a possible discovery of an extrasolar planet!
It seems strange now, but back then we really did not know if there were any other planets around other stars.
A lot of astronomers thought that it was quite likely that there were planets around other stars, maybe even most stars, but we had no data.
We were getting there, there were astrometric and radial velocity searches underway, with people like Walker, Griffin and Latham developing techniques which would clearly,…
catdynamics | September 30, 2010So, what do we make of the NRC Rankings?
What drives the different rankings, and what are the issues and surprises?
First, the R-rankings really are reputational - they are a bit more elaborate than just asking straight up, but what they reduce to is direct evaluation by respondents without evaluating quantitative indicators.
Doug at nanoscale puts it well - the S-Rankings are really generally better indicators...
A new index W = R - S has been named the "hard work" index.
BTW - you can't take (R+S)/2 and call it a rank - you need to rank the resulting score and count the ordinal position…
catdynamics | September 28, 2010The NRC rankings are out.
Penn State Astronomy is ranked #3 - behind Princeton and Caltech.
W00t!
PSU doing the mostest with the leastest.
The Data Based Assessment of Graduate Programs by the National Research Council, for 2010, is out, reporting on the 2005 state of the program.
The full data set is here
EDIT: PhDs.org has a fast rank generator by field.
Click on the first option (NRC quality) to get R-rankings, next button ("Research Productivity") to get the S-rankings, or assign your own weights to get custom ranking.
Astronomy S-Rankings:
Princeton
Caltech
Penn State
Berkeley…
catdynamics | September 28, 2010Two aspects of the NRC rankings are that a) it took so long that the results are dated and people will selectively choose to use or ignore them as suits best (and then rely on the 1995 rankings instead I gather)
and, b) the process was so hard and unpleasant it will never be done again...
Hmm, that sounds familiar.
We can fix that.
See, the arduous part of the NRC was the data mining - gathering the metrics after they'd been defined.
It took a long time and required iterations and debate.
But, this is precisely the sort of thing that can be automated.
At least in large part.
eg. the…