hoggresearch.blogspot.com
Hogg's Research: momentum-driven winds, enfastening stellar models
http://hoggresearch.blogspot.com/2015/07/momentum-driven-winds-enfastening.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Momentum-driven winds, enfastening stellar models. By a factor of five-ish. It relates to the fact that there are multiple scatterings of the radiation. Andrea Macció's (MPIA but soon NYU-AD) showed some nice work on simulations of small galaxies that are infalling in to the halos of larger galaxies. Mike O'Neil came down to HD for two days (from Frankfurt) and we spent part of the afternoon understanding how to run and interpret PICO.
hoggresearch.blogspot.com
Hogg's Research: #streams2015, day 4
http://hoggresearch.blogspot.com/2015/07/streams2015-day-5.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Streams2015, day 4. As a result of crippling disorganization, blog posting has gone pear-shaped. I will be posting out-of-date posts with correct dates (and 23:59 time stamps), but possibly considerably after the fact and out of chronological order.]. Another great day at Ringberg Castle today. For me, the highlight was an unconference session called Gaia Zero-Day Exploit. Which was about what we could do immediately upon release of Gaia.
hoggresearch.blogspot.com
Hogg's Research: #streams2015, day 3
http://hoggresearch.blogspot.com/2015/07/streams2015-day-3.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Streams2015, day 3. After Grillmair, Sesar (MPIA) showed a beautiful analysis of the new Ophiuchus stream, where he measures everything via probabilistic inference. Kallivayalil (Virginia) showed the evidence for the LMC proper motion measurement. I am a believer! Subscribe to: Post Comments (Atom). I must post five days per week (I choose which five), except when traveling, no matter what I have done. Use the content with caution. The pr...
hoggresearch.blogspot.com
Hogg's Research: #streams2015, day 5
http://hoggresearch.blogspot.com/2015/07/streams2015-day-5_24.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Streams2015, day 5. Today was the last (and half) day of the Ringberg meeting. At breakfast, we discussed an argument James Binney (Oxford) had made the previous day about n-body simulations not. The drive home was a long discussion between Rix and me about all that had happened and what to do next. We are fired up about new approaches to stream searching, to use now on SDSS. Subscribe to: Post Comments (Atom). Use the content with caution.
hoggresearch.blogspot.com
Hogg's Research: 2015-06
http://hoggresearch.blogspot.com/2015_06_01_archive.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Star-formation history of the Milky Way. I read (or skimmed, really) some classic papers on the star-formation history of the Milky Way, in preparation for re-asking this question with APOGEE. Data this summer. Papers I skimmed included Prantzos and Silk. Which infers the SFH from (mainly) abundance distributions and Gizis, Reid, and Hawley. Links to this post. Yet more K2 proposal. Links to this post. Links to this post. Campaign 9. ...
hoggresearch.blogspot.com
Hogg's Research: likelihood functions for stellar age relations
http://hoggresearch.blogspot.com/2015/08/likelihood-functions-for-stellar-age.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Likelihood functions for stellar age relations. Bird (Vanderbilt) and I pair-coded a likelihood function for the age–velocity relation in the Milky Way Disk. After that, I coded up a likelihood function for the star-formation history in the Milky Way disk, given very noisy age estimates (from The Cannon. Price-Whelan, Rix, and I discussed a brute-force search for stellar streams in stellar catalogs called KingKong. I'm on the web here.
hoggresearch.blogspot.com
Hogg's Research: 2015-07
http://hoggresearch.blogspot.com/2015_07_01_archive.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. I gave the Königstuhl Colloquium on data-driven models. With preparing for that and a long lunch, no other research today! Links to this post. Milky Way disk kinematics. Data plus stellar ages from Ness's recent work with The Cannon. Links to this post. At Milky Way group meeting, Price-Whelan talked about chaotic streams, Gail Zasowski (JHU) talked about the SDSS. In the afternoon, Rix and I worked with Bird to turn his empirical velocit...
hoggresearch.blogspot.com
Hogg's Research: model derivatives
http://hoggresearch.blogspot.com/2015/08/model-derivatives.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Today Yuan-Sen Ting (Harvard) gave Ness and me derivatives of Kurucz-like models of APOGEE. Spectral data with respect to individual element abundances and effective temperature and gravity. Ness and I plotted these theoretical derivatives against “beliefs” obtained by The Cannon. Sbout these same dependencies. They agree remarkably well! Can detect or measure individual abundances are very, very high. Subscribe to: Post Comments (Atom).
hoggresearch.blogspot.com
Hogg's Research: observing radial migration in the disk
http://hoggresearch.blogspot.com/2015/08/observing-radial-migration-in-disk.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Observing radial migration in the disk. At MPIA Milky Way group meeting, Rix talked about the recent paper by Sanders and Binney about extended distribution functions using a series of very simple, analytic prescriptions of various inputs. I objected to the paper: I don't see any reason to work with simulation-output-inspired simple functional forms when you have actual simulation outputs! And a similar piece of code executing. It looks l...
hoggresearch.blogspot.com
Hogg's Research: stellar ages in the Milky Way disk
http://hoggresearch.blogspot.com/2015/07/tuesday.html
Galaxies, stellar dynamics, exoplanets, and fundamental astronomy. Stellar ages in the Milky Way disk. OMG I am so stoked! I made plots of the ages of the APOGEE. Red-clump stars as a function of position in the Milky Way and got the image below (one plot of many). You can see the thin disk jump out but you can also see a flaring of the young disk at large radius that Rix and Bovy told Ness and me we should expect. Subscribe to: Post Comments (Atom). This site records research in progress. Streams2015, d...
