Monday, April 27, 2009

How (not) to reform the University system

"End the University as we know it" implores Mark Taylor in a NYT Op-Ed, wherein he, chair of the Religion Department at Columbia, suggests that Universities should abolish traditional departments and only consider multi-disciplinary short-term projects (he generously suggests renewals based on evaluation every seven years) that have "practical" use.

If you've just choked on your coffee at a call by a religious studies scholar for Universities to focus only on practical problems you're not alone. For a moment I thought this was an April Fools day joke, but sadly it is not. Note that Taylor is not advocating getting rid of himself, for

These vexing practical problems cannot be adequately addressed without also considering important philosophical, religious and ethical issues. After all, beliefs shape practices as much as practices shape beliefs.
Seeing as we're only allowed to consider "practical" research I look forward to seeing religious studies' aid in producing improved anti-HIV drugs, a cure for cancer, improved climate models and practical nuclear fusion.

Now there are one or two truths within the Op-Ed. There are problems with the way graduate students are used, and whether their apprenticeships adequately or fairly serve their long-term career interests (at least, in astrophysics we seem to think there are such problems, see e.g. see Williams et al, arXiv:0904.2571 [ps, pdf, other], but see below). But its hard to imagine a set solutions, less practical, less realistic or more myopic than those Taylor proposes.

When Taylor resigns his tenure, convinces all of his colleagues to do the same, reorganizes (nay, completely dissolves) the organization structure of his department while still producing a number practical solutions to World problems by following his suggested pseudo-libertarian course of action, then we might consider evaluating whether we should implement some of his reforms or not.

Go read the editorial to see exactly what he is proposing.

[Updated: 3:40pm. Michael Bérubé points out this response by Marc Bousquet. Interestingly Bousquet argues that the "Universities produce more grad students than they can employ" is a myth, at least if you sent them all to teaching colleges. That may be true, but it is a somewhat disingenuous counter argument as not everyone wants a pure teaching position - many people enter academia because they want to do a fair bit of research. There is more to his rebuttal than just that, so go read it too.]

Friday, April 24, 2009

Interesting Astrophysics: 20 Apr to 24 Apr

Another Friday dose of interesting astronomy preprints and accepted papers. It has been a relatively quite week, with perhaps the most interesting article being a Astro2010 Decadal Survey White Paper by Williams et al on problems with the current career structure in US astronomy.

Galaxies and Starbursts

Young stellar populations and star clusters in NGC 1705
F. Annibali, M. Tosi, M. Monelli, M. Sirianni, P. Montegriffo, A. Aloisi, L. Greggio, arXiv:0904.3257 [ps, pdf, other]
Comments: Accepted for publication on AJ

Star formation in extremely faint dwarf galaxies
Sambit Roychowdhury, Jayaram N. Chengalur, Ayesha Begum, Igor D. Karachentsev, arXiv:0904.2748 [ps, pdf, other]
Comments: Accepted for publication in MNRAS, 14 pages (+6 pages as appendix), 5 tables, 8 figures (+2 figures in appendix)

Standard empirical star formation laws (e.g. Kennicutt relation) do not appear to work at the very low levels of SF in these objects.

Understanding Lyman-alpha emitters
Kim K. Nilsson, Klaus Meisenheimer, Nicholas Bond, Eric Gawiser, Harold Francke, Daniel Kunth, Toru Yamada, Goran Ostlin, arXiv:0904.3335 [ps, pdf, other]
Comments: Workshop summary of the "Understanding Lyman-alpha Emitters" meeting in Heidelberg, Oct. 2008, 49 pages (seven contributions), to be published in New Astronomy Review. Conference home-page, with presentations, is this http URL

Black Holes and AGN

On The Maximum Mass of Stellar Black Holes
Krzysztof Belczynski, Tomasz Bulik, Chris L. Fryer, Ashley Ruiter, Jorick S. Vink, Jarrod R. Hurley, arXiv:0904.2784 [ps, pdf, other]
Comments: 12 pages, ApJ submitted

AGN with strong forbidden high-ionisation lines selected from the Sloan Digital Sky Survey
Jonathan M. Gelbord, James R. Mullaney, Martin J. Ward, arXiv:0904.3156 [ps, pdf, other]
Comments: 31 pages, 19 figures. Includes 12 pages (5 figures, 7 tables) of online-only material. To appear in MNRAS. Also available from this http URL

Instrumentation and Archives

MegaPipe: the MegaCam image stacking pipeline
Stephen D.J. Gwyn, arXiv:0904.2568 [ps, pdf, other]
Comments: 4 pages. To appear in the procedings of ADASS 2008. 1500 square degrees of calibrated and stacked ugriz data publicly available at: this http URL and this http URL

Stars, Supernovae and Planets

X-Ray Spectroscopy of Stars
M. Guedel, Y. Naze, arXiv:0904.3078 [ps, pdf, other]
Comments: accepted for Astron. Astrophys. Rev., 98 journal pages, 30 figures (partly multiple); requires bibtex

Rates and Delay Times of Type Ia Supernovae
Ashley J. Ruiter, Krzysztof Belczynski, Chris L. Fryer, arXiv:0904.3108 [pdf, other]
Comments: 14 pages, 2 tables, 3 figures, submitted to ApJ


Training the Next Generation of Astronomers
Peter K. G. Williams, et al, arXiv:0904.2571 [ps, pdf, other]

Comments: 9 pp + cover page; position
paper submitted to the Astro2010 Decadal Survey Subcommittee on the
State of the Profession; small typographical corrections made;
submitted version at this http URL

In my opinion this is one of the most important White Papers I've seen. The fact is that the out-of-equilibrium career environment young astronomers find themselves in the US wastes talent, people's lives and taxpayer money. The Universities themselves don't suffer: there are always more than enough skilled researchers applying for tenure, and the larger number of skilled astronomers that don't get one of the few tenure spots bringing in even more money to the Universities through grants until they tire of the rat race and leave academia. The Universities have no financial incentive to stop cranking out vastly more PhDs than the system can support, nor to be honest about to their students and Post Docs about their chances of having a stable long term academic career.

Anyway, read the White Paper. I had hoped it would have been more quantitative. If anything I think it underestimates the current problem by focusing more on graduate students and Post Docs and ignoring the massive log-jam associated with post-Post Doctoral researchers in "soft money" positions, but perhaps that is just my bias as a disaffected soft money researcher.

Their abstract is: "While both society and astronomy have evolved greatly over the past fifty years, the academic institutions and incentives that shape our field have remained largely stagnant. As a result, the astronomical community is faced with several major challenges, including: (1) the training that we provide does not align with the skills that future astronomers will need, (2) the postdoctoral phase is becoming increasingly demanding and demoralizing, and (3) our jobs are increasingly unfriendly to families with children. Solving these problems will require conscious engineering of our profession. Fortunately, this Decadal Review offers the opportunity to revise outmoded practices to be more effective and equitable. The highest priority of the Subcommittee on the State of the Profession should be to recommend specific, funded activities that will ensure the field meets the challenges we describe. "

Friday, April 17, 2009

Interesting Astrophysics: Apr 13 to Apr 17

A lot of interesting galaxy-related stuff came out this week, either in the journals or on astro-ph. Of particular note there is a new radio supernova in M82 (Brunthaler et al), two papers on IR observations of star-forming galaxies (Siana et al; Weedmand and Houck) and even a paper on post-starburst galaxies (Wild et al). Everett et al expand on their work on hybrid Cosmic Ray plus Thermal galactic winds, and Maddox et al look at the X-ray emission from the N11 superbubble in the LMC.

Galaxies and Starbursts

Discovery of a bright radio transient in M82: a new radio supernova?
A. Brunthaler, K.M. Menten, M.J. Reid, C. Henkel, G.C. Bower, H. Falcke, arXiv:0904.2388 [ps, pdf, other]
Comments: submitted to Astronomy & Astrophysics, 4 pages, 3 figures, also available at this http URL

This is pretty cool - a new bright radio source has appeared near the kinematic center of M82, possibly a radio supernova.

Post-starburst galaxies: more than just an interesting curiosity

Vivienne Wild, C. Jakob Walcher, Peter H. Johansson, Laurence Tresse, Stéphane Charlot, Agnieszka Pollo, Olivier Le Fèvre and Loic de Ravel, 2009, MNRAS, 395, 144
Full Text: HTML, PDF (Size: 1562K)

Detection of PAH and Far-Infrared Emission from the Cosmic Eye: Probing the Dust and Star Formation of Lyman Break Galaxies
Brian Siana, Ian Smail, A. Mark Swinbank, Johan Richard, Harry I. Teplitz, Kristen E. K. Coppin, Richard S. Ellis, Daniel P. Stark, Jean-Paul Kneib, Alistair C. Edge, arXiv:0904.1742 [ps, pdf, other]
Comments: Accepted for publication in ApJ. 9 pages, 7 figures

Evolution of the Most Luminous Dusty Galaxies
Daniel W. Weedman, James R. Houck, arXiv:0904.2331 [ps, pdf, other]
Comments: Accepted for publication in The Astrophysical Journal

Spitzer IRS observations for a significant number of ULIRGs, tabulates the 8 micron fluxes.

Synchrotron Constraints on a Hybrid Cosmic-Ray and Thermally-Driven Galactic Wind
John E. Everett, Quintin G. Schiller, Ellen G. Zweibel, arXiv:0904.1964 [ps, pdf, other]
Comments: 13 pages, 8 figures; submitted to ApJ; comments and questions welcome

Hitting the Bull's-eye: The Radial Profile of Accretion and Star Formation in the Milky Way
J. E. G. Peek, arXiv:0904.2000 [pdf, other]
Comments: 9 pages, 5 figures, accepted to the ApJ

Understanding Global Galactic Star Formation
Paul A. Scowen. et al, arXiv:0904.2002 [pdf]
Comments: 8 pages - Science White Paper for the Astro2010 Decadal Survey Panel(s): Planetary Systems and Star Formation; Stars and Stellar Evolution

The evolution of the mass-metallicity relation in galaxies of different morphological types
F. Calura, A. Pipino, C. Chiappini, F. Matteucci, R. Maiolino, arXiv:0904.2180 [ps, pdf, other]
Comments: 20 pages, 13 figures, accepted by Astronomy & Astrophysics

Reproduces galaxy mass-metallicity (MZ) relationship using increasing SF efficiency in more massive galaxies, without the need for outflows. This is hardly surprising, as even outflow advocates acknowledge that most/much of the MZ relationship is driven by the different amount of gas consumption and thus relative degree of chemical evolution of host galaxies of different mass. Unfortunately Calura et al don't show what the galaxy mass versus effective yield (M-yeff) relationship predicted by their model, which is annoying as the M-yeff would take this effect out and observationally still shows apparent metal loss in low mass galaxies (although c.f. Dalcanton '07, who showed yeff is not always an honest tracer).


Big Bang Nucleosynthesis: The Strong Force meets the Weak Anthropic Principle
J. MacDonald, D. J. Mullan, arXiv:0904.1807 [ps, pdf, other]
Comments: 13 figures

Numerical Methods and Numerical Astrophysics

PCA Tomography: how to extract information from data cubes
J. E. Steiner, R. B. Menezes, T. V. Ricci and A. S. Oliveira, 2009, MNRAS, 395, 64
Full Text: HTML, PDF (Size: 20939K)

The Fate of High-Velocity Clouds: Warm or Cold Cosmic Rain?
Fabian Heitsch, Mary E. Putman, arXiv:0904.1995 [ps, pdf, other]
Comments: 12 pages, 8 figures, accepted by ApJ

Stars, Supernovae and Planets

Nonthermal X-ray Emission from the N11 Superbubble in the Large Magellanic Cloud
L.A. Maddox, R.M. Williams, B.C. Dunne, Y.-H Chu, arXiv:0904.1821 [ps, pdf, other]
Comments: 16 pages, 3 figures, submitted to ApJ

Short-term Effects of Gamma Ray Bursts on Earth
Osmel Martín, Douglas Galante, Rolando Cárdenas, J.E. Horvath, arXiv:0904.1755 [pdf]
Comments: 13 pp., to appear in Astrophysics and Space Science

Friday, April 10, 2009

Interesting Astrophysics: Apr 06 to Apr 10

It has been a relatively quiet week in terms of papers and preprints that I consider interesting enough to make a note of. Perhaps the most interesting is Martinez and Trimble's "Cosmologists in the dark", largely as it is a historical review rather than a technical paper.

Galaxies and Starbursts

An ultraviolet study of nearby luminous infrared galaxies: star formation histories and the role of AGN
Sugata Kaviraj, 2009, MNRAS, 394, 1167
Full Text: HTML, PDF (Size: 13559K)

Over half of the far-infrared background light comes from galaxies at z > 1.2
Mark J. Devlin, et al, arXiv:0904.1201 [pdf]
Comments: Accepted to Nature. Maps available at this http URL
Journal-ref: Nature, vol. 458, 737-739 (2009)

BLAST: A Far-Infrared Measurement of the History of Star Formation
Enzo Pascale, et al, arXiv:0904.1206 [ps, pdf, other]
Comments: Submitted to ApJ. Maps available at this http URL

X-ray nuclear activity in nearby galaxies
Wei Ming Zhang, Roberto Soria, Shuang Nan Zhang, Douglas A. Swartz, JiFeng Liu, arXiv:0904.1091 [ps, pdf, other]
Comments: 27 pages, 353 kB, accepted by ApJ


Cosmologists in the dark
Vicent J. Martinez, Virginia Trimble, arXiv:0904.1126 [ps, pdf, other]
Comments: 10 pages, ASP style (asp2006.sty), invited talk, to be published in the proceedings of the conference "Cosmology across Cultures" (held at Granada, Spain, on 2008, September 8th to 12th), J. A. Belmonte, F. Prada, J. A. Rubino Martin, & A. Alberdi, Eds., ASP, S. Francisco. Comments are welcome

A nice discussion of the history of the last century of cosmology that maintains a fair balance in its critiques. It certainly does a nice job of discussing the problems with Steady State and Quasi Steady State models. The title, which you might think of as a dig at cosmologists, is actually in reference to the quote from T.S. Elliot's "East Coker" (which I'm sure you know, or should know anyway).

Black Holes and AGN

The Contribution of Active Galactic Nuclei to the Microjansky Radio Population
D.R. Ballantyne, arXiv:0904.0996 [ps, pdf, other]
Comments: 30 pages, 11 figures, accepted by the ApJ

Active Galactic Nuclei with Starbursts: Sources for Ultra High Energy Cosmic Rays
P.L. Biermann, J.K. Becker, L. Caramete, L. Gergely, I.C. Maris, A. Meli, V. de Souza, T. Stanev, arXiv:0904.1507 [ps, pdf, other]
Comments: 4 pages, 1 figure, proceedings of "High-Energy Gamma-rays and Neutrinos from Extra-Galactic Sources", Heidelberg

Quasar Feedback: More Bang for Your Buck
Philip F. Hopkins, Martin Elvis, arXiv:0904.0649 [ps, pdf, other]
Comments: 7 pages, 2 figures, submitted to MNRAS

Meh. I must be feeling extra cynical today as I really don't think this says anything new other than collecting old results together and packaging them together with a cartoon picture.

Numerical Astrophysics and Hydrodynamics

The turbulent destruction of clouds – I. A k–ε treatment of turbulence in 2D models of adiabatic shock–cloud interactions
J. M. Pittard, S. A. E. G. Falle, T. W. Hartquist, J. E. Dyson, 2009, MNRAS, 394, 1351
Full Text: HTML, PDF (Size: 52479K)

Numerical approaches to star formation and SuperNovae energy feedback in simulations of galaxy clusters
Martina Giovalli, arXiv:0904.1399 [pdf, other]
Comments: Ph.D. Thesis, 203 pages

Note to self: Might be good. Try to find the time to read this carefully.

Stars, Supernovae and Planets

The Core-collapse rate from the Supernova Legacy Survey
G. Bazin, et al, arXiv:0904.1066 [ps, pdf, other]
Comments: accepted Astronomy and Astrophysics

On the Mass and Metallicity Distributions of the Parent AGB Stars of O-rich Presolar Stardust Grains
Larry R. Nittler, arXiv:0904.1388 [ps, pdf, other]
Comments: 8 pages, 5 figures; accepted for publication in the Publications of the Astronomical Society of Australia

I found this part of the abstract particularly interesting: "3) The Sun appears to have a moderately low metallicity for its age and/or unusual 17O/16O and 18O/16O ratios for its metallicity. 4) The Solar 17O/18O ratio, while unusual relative to present-day molecular clouds and protostars, was not atypical for the presolar disk and does not require self-pollution of the protosolar molecular cloud by supernova ejecta."

Thursday, April 09, 2009

Forensic Astronomy with Don Olson

The latest edition of the Smithsonian Magazine (April 09 edition) has an article (available online here) about Texas State astronomer Donald Olson, who

solves puzzles in literature, history and art using the tools of astronomy: charts, almanacs, painstaking calculations and computer programs that map ancient skies. He is perhaps the leading practitioner of what he calls "forensic astronomy."
Pretty neat stuff, although worth seeing in print as the online edition only shows a single image.

While some in the art world welcome Olson's input, others seem to react poorly to learning what, when or where famous painters actually painted their works. I love Olson's pragmatic response to this:
"You can't ruin a painting's mystique through technical analysis," Olson says. "It still has the same emotional impact. We are just separating the real from the unreal."

Monday, April 06, 2009

What a drag

I've spent a busy but interestingly different day spent investigating drag coefficients for my newest project on the cool material entrained within starburst-driven superwinds. Although wikipedia has some useful background information its hard to track down exact references, and to determine the exact Reynold numbers over which the drag coefficients apply.

And pretty much all of the numbers I can find apply to rigid bodies in incompressible flows, whereas I'm interested in deformable clouds embedded in supersonic flows, and in particular sources of information other than the few astrophysical papers that mention cloud drag coefficients (for reasons that are too complicated to explain here).

There quite a few non-astro papers on liquid droplets, e.g. water droplets, both experimental and numerical, but almost all are in the low Reynolds number limit (i.e. Stokes drag).

Ultimately I failed to find exactly what I was looking for, but in the process I did come across this paper:

The drag force on an American football

Am. J. Phys. 71, 791 (2003)

Its neat the someone actually went out and built an experimental apparatus to measure the drag coefficient of a football. In case you're interested, CD is ~0.05 - 0.06 for Re > 1e5.

Friday, April 03, 2009

Interesting Astrophysics: Mar 30 to Apr 03

Its raining in Baltimore. Another fine day for science!

There are a variety of interesting BH/AGN-related papers this week, in particular discussing the filling factor of AGN wind (Blustin & Fabian), UV-outflows in Seyferts (Stoll) and isotropic luminosity indicators for AGN (Diamond-Stanic).

Julian Pittard has a nice new paper on 3-D modelling of colliding stellar winds, and Christensen-Dalsgaard has a nice review of the Sun as the fundamental calibrator for theories of stellar evolution.

Galaxies and Starbursts

The mass-metallicity relation in galaxy clusters: the relative importance of cluster membership versus local environment
Sara L. Ellison, Luc Simard, Nicolas B. Cowan, Ivan K. Baldry, David R. Patton, Alan W. McConnachie, arXiv:0903.4684 [ps, pdf, other]
Comments: MNRAS, accepted

Early assembly of the most massive galaxies
Chris A. Collins, et al, arXiv:0904.0006 [ps, pdf, other]
Comments: Published in Nature 2nd April 2009. This astro ph version includes main text and supplementary material combined

The Star Formation Law in Atomic and Molecular Gas
Mark R. Krumholz, Christopher F. McKee, Jason Tumlinson, arXiv:0904.0009 [ps, pdf, other]
Comments: 7 pages, 2 figures, emulateapj format, submitted to ApJ

Dust in the Early (z>1) Universe
Fabian Walter, arXiv:0904.0152 [ps, pdf, other]
Comments: 20 pages, review to appear in "Cosmic Dust -- Near and Far", ed. Th. Henning, E. Grun, J. Steinacker (ASP Conf. Series)

Discovery, Photometry, and Kinematics of Planetary Nebulae in M 82
L. C. Johnson, R. H. Mendez, A. M. Teodorescu, arXiv:0904.0266 [ps, pdf, other]
Comments: 16 pages, 13 figures, Accepted by ApJ

Derive a distance to M82 using the PNLF of 4.2+/-0.4 Mpc, rather higher than TRGB distances of ~3.6 Mpc to both M81 and M82. Suggest that all their PNs suffer significant extinction, of order 0.4 magntitudes, which when corrected for reconciles distances. Also claim that PN-based rotation curve shows known weird falling rotation curve.

Black Holes and AGN

Radio constraints on the volume filling factors of AGN winds
A. J. Blustin, A. C. Fabian, arXiv:0904.0209 [ps, pdf, other]
Comments: 6 pages, accepted by MNRAS

Parsec-scale dust distributions in Seyfert galaxies - Results of the MIDI AGN snapshot survey
Konrad R. W. Tristram, et al, arXiv:0903.4892 [ps, pdf, other]
Comments: 19 pages, 8 figures, submitted to A&A, recommended for publication

Scaling ultraviolet outflows in Seyferts
R. Stoll, S. Mathur, Y. Krongold, F. Nicastro, arXiv:0903.5310 [ps, pdf, other]
Comments: 7 pages, 5 figures, submitted to ApJ

A Photoionized Nebula Surrounding and Variable Optical Continuum Emission from the Ultraluminous X-Ray Source in NGC 5408
Philip Kaaret, Stephane Corbel, arXiv:0903.5329 [ps, pdf, other]
Comments: accepted by ApJ, 8 pages

Isotropic Luminosity Indicators in a Complete AGN Sample
Aleksandar M. Diamond-Stanic, George H. Rieke, Jane R. Rigby, arXiv:0904.0250 [ps, pdf, other]
Comments: 9 pages, 4 figures, accepted for publication in ApJ

Note to self: NGC 3079 is in their sample.


A Hydrodynamical Analysis of the Steady-State Shock Model
A. Preite Martinez, 2009, Open Astronomy Journal , 2, 1.

Stars, Supernovae and Planets

Gamma-Ray Bursts as a Threat to Life on Earth
Brian C. Thomas, arXiv:0903.4710 [pdf]
Comments: 8 pages; submitted as part of proceedings of the ESLAB Symposium on 'Cosmic Cataclysms and Life', November 2008; to be published in a special issue of the International Journal of Astrobiology

3D Models of Radiatively Driven Colliding Winds In Massive O+O Star Binaries: I. Hydrodynamics
J. M. Pittard, arXiv:0904.0164 [ps, pdf, other]
Comments: 21 pages, 15 figures, accepted for publication in MNRAS

Very nice science from Julian, as always. Nice figures too.

The Sun as a fundamental calibrator of stellar evolution
J. Christensen-Dalsgaard, arXiv:0904.0358 [ps, pdf, other]
Comments: To appear in Proc. IAU Symposium 258, The Ages of Stars, eds E. E. Mamajek, D. R. Soderblom & R. F. G. Wyse, IAU and Cambridge University Press

Interesting wrt stellar age, stellar evolution, and also the ongoing controvsery regarding Solar abundances (see discussion at end).