Interesting Astrophysics: Mar 18 to Mar 22

Not one but three theoretical papers with some relevance to galactic winds this week, although all quite different types of winds. Dogiel and Breitschwerdt discuss cosmic-ray -driven winds, Silich et al further explore their radiative (thermal) star cluster wind solution, and Kurosawa and Proga discuss AGN-driven winds.

In addition to this windy goodness there are also a variety of interesting papers on galaxies, LINERs, IFU spectroscopy, and gas-phase element depletion factors. Enjoy!

There will not be an edition of "Interesting Astrophysics" next week as I'll be away all week at the The Chemical Enrichment of the Intergalactic Medium meeting in Leiden.

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Galaxies and Starbursts

A Young Super Star Cluster in the Nuclear Region of NGC 253
Kornei, Katherine A., McCrady, Nate, 2009, ApJ, 697, 1180
PDF (406 KB) | HTML

A Super Bubble Candidate in the Galactic Center and a Local Enhancement G359.77-0.09
Hideyuki Mori, Yoshiaki Hyodo, Takeshi Go Tsuru, Masayoshi Nobukawa, Katsuji Koyama, arXiv:0905.2725 [ps, pdf, other]
Comments: 9 pages, 7 figures, accepted for publication in PASJ

Extragalactic chemical abundances: do HII regions and young stars tell the same story? The case of the spiral galaxy NGC 300
Fabio Bresolin, Wolfgang Gieren, Rolf-Peter Kudritzki, Grzegorz Pietrzynski, Miguel A. Urbaneja, Giovanni Carraro, arXiv:0905.2791 [pdf, other]
Comments: Accepted for publication in The Astrophysical Journal

Cosmic Rays in the Disk and Halo of Galaxies
V.Dogiel, D. Breitschwerdt, arXiv:0905.3071 [ps, pdf, other]
Comments: Accepeted in ESA Publication Series, 2009

Personally I disagree with attempting to lump theoretical model CR-driven galactic winds in with the winds we actually see in actively star-forming galaxies, for which we have good evidence that they're gas pressure-driven galactic winds (i.e. by supernova and stellar winds). CRs are present in starburst-driven winds, but they're not energetically dominant, and CR-driven wind solutions have quite distinctively different kinematics from observations and theory of starburst-driven winds.

On the Heating Efficiency Derived from Observations of Young Super Star Clusters in M82
Sergiy Silich, Guillermo Tenorio-Tagle, Ana Torres Campos, Casiana Munoz-Tunon, Ana Monreal-Ibero. Veronica Melo, arXiv:0905.3192 [ps, pdf, other]
Comments: 15 pages, 3 figures, accepted for publication in The Astrophysical Journal

Ah, but the real question is how significant are the most massive clusters to the total star formation rate in M82 starburst region? Ultimately, not that significant, as least that is what we concluded (Strickland & Heckman, 2009, ApJ, 697, 2030).

Line and Continuum Emission from the Galactic Center. III. Origin of 6.4 keV Line Emission from Molecular Clouds in the Galactic Center
Vladimir Dogiel, Kwong-Sang Cheng, Dmitrii Chernyshov, Aya Bamba, Atsushi Ichimura, Hajime Inoue, Chung-Ming Ko, Motohide Kokubun, Yoshitomo Maeda, Kazuhisa Mitsuda, Noriko Y. Yamasaki, arXiv:0905.3075 [ps, pdf, other]
Comments: Accepted in PASJ, to be published in PASJ Vol.61 No.5, 2009

Star formation and nuclear activity in close pairs of early-type galaxies
Ben Rogers, Ignacio Ferreras, Sugata Kaviraj, Anna Pasquali, Marc Sarzi, arXiv:0905.3386 [ps, pdf, other]
Comments: 11 pages, 9 figures, 1 table. Submitted for publication in MNRAS

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Black Holes and AGN

On the large-scale outflows in active galactic nuclei: consequences of coupling the mass-supply rate and accretion luminosity
Ryuichi Kurosawa, Daniel Proga, arXiv:0905.2965 [ps, pdf, other]
Comments: 14 pages, 7 figures, accepted for publication in MNRAS

An X-ray view of 82 LINERs with Chandra and XMM-Newton data
O. Gonzalez-Martin, J. Masegosa, I. Marquez, M. Guainazzi, E. Jimenez-Bailon, arXiv:0905.2973 [pdf]

Comments: Accepted for publications in Astronomy and Astrophysics, 49 pages, 12 figures. Catalogs only at: this http URL

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Other

The integral field spectroscopy (IFS) wiki
M.S. Westmoquette, K.M. Exter, L. Christensen, M. Maier, M. Lemoine-Busserolle, J. Turner, T. Marquart, arXiv:0905.3054 [pdf, other]

Comments: This article accompanies the opening of the IFS wiki site this http URL

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The Interstellar Medium

A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
Edward B. Jenkins, arXiv:0905.3173 [ps, pdf, other]
Comments: 166 pages, 21 figures, pages 116-166 contain detailed tabulations that may not be of interest to most readers. Accepted for publication in the Astrophysical Journal

Its only 166 pages! Get reading now.

SN thermalization efficiency paper published!

O frabjous day! Callooh! Callay!

Our paper on theoretically-derived constraints on the supernova thermalization efficiency and central mass loading of M82's starburst-driven galactic wind is no longer "in press," but has been published. No longer will you have to make do with the arXiv preprint version.

"Supernova Feedback Efficiency and Mass Loading in the Starburst and Galactic Superwind Exemplar M82", Strickland & Heckman, The Astrophysical Journal, 2009, 697, 2030-2056.
See http://www.iop.org/EJ/abstract/0004-637X/697/2/2030

[The image is of a 5 kpc x 5kpc region centered on M82's nucleus in soft, medium and hard X-ray bands as observed with the Chandra X-ray Observatory]

Interesting Astrophysics: 04 May to 15 May

This time we have two weeks work of interesting preprints and papers. There is a short theoretical paper on starburst-driven wind (Nath & Silk), a smorgasbord of galaxy-related papers, and quite a few interesting supernovae-related papers.

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Galaxies and Starbursts

Starburst--driven galactic outflows
Biman B. Nath, Joseph Silk, arXiv:0905.0314 [ps, pdf, other]
Comments: 5 pages, 4 figures, to appear in MNRAS (Letters)

Radiation-pressure driving for superwinds. Haven't read this in depth yet, so can't comment too much, but it worries me that it appears based on incorrect assumptions regarding the empirical velocity versus star formation rate relationship.

Turning Back the Clock: Inferring the History of the Eight O'clock Arc
Steven L. Finkelstein, Casey Papovich, Gregory Rudnick, Eiichi Egami, Emeric Le Floc'h, Marcia J. Rieke, Jane Rigby, Christopher N.A. Willmer, arXiv:0905.1122 [ps, pdf, other]
Comments: Accepted to the Astrophysical Journal. 11 pages, 7 figures, 4 tables

Effects of ram pressure on the gas distribution and star formation in the Large Magellanic Cloud
Chiara Mastropietro, Andreas Burkert, Ben Moore, arXiv:0905.1126 [ps, pdf, other]
Comments: 18 pages, 18 figures, submitted to MNRAS

A holistic view on ram pressure stripping in the Virgo cluster - The first complete model-based time sequence
B. Vollmer, arXiv:0905.1770 [ps, pdf, other]
Comments: 10 pages, 5 figures; accepted for publication in A&A

An Evolutionary Paradigm for Dusty Active Galaxies at Low Redshift
D. Farrah, B. Connolly, N. Connolly, H. Spoon, S. Oliver, H. Prosper, L. Armus, J. R. Houck, A. R. Liddle, V. Desai, arXiv:0905.1956 [ps, pdf, other]
Comments: ApJ accepted. Comments welcome. We suggest reading section 2 before looking at the figures. 26 pages, 21 figures, 1 table

Star Formation in Luminous HII regions in M33
Monica Relano, Robert C. Kennicutt Jr., arXiv:0905.1158 [ps, pdf, other]

Comments: 46 pages, 12 figures, accepted for publication in The Astrophysical Journal; pdf format available at this http URL

The relationship between star formation rate and radio synchrotron luminosity at 0 < z < 2
Timothy Garn, David A. Green, Julia M. Riley, Paul Alexander, arXiv:0905.1218 [ps, pdf, other]
Comments: 12 pages, 1 table, 12 figures. Accepted for publication in MNRAS

The Cartwheel galaxy with XMM-Newton
Erika Crivellari, Anna Wolter, Ginevra Trinchieri, arXiv:0905.1230 [ps, pdf, other]
Comments: 10 pages, to be published in A&amp;A

The Galactic Environment of the NeVIII Absorber toward HE0226-4110

John S. Mulchaey, Hsiao-Wen Chen, arXiv:0905.1327 [ps, pdf, other]

Comments: Accepted for Publication in ApJ Letters; 5 journal-style pages and 1 figure; full-resolution version is available at this http URL

On The Origin of Lyman-alpha Absorption in Nearby Starbursts and Implications for Other Galaxies
Hakim Atek, Daniel Schaerer, Daniel Kunth, arXiv:0905.1329 [ps, pdf, other]
Comments: 11 pages, 10 figures. Accepted for publication in Astronomy and Astrophysics

H II regions, infrared dark molecular clouds and the local geometry of the Milky Way's nuclear star-forming ring
H. S. Liszt, arXiv:0905.1412 [pdf, other]
Comments: 14 Figures 15 pages, submitted to A&amp;A 9 May 2009, figures are slightly degraded in this version to accomodate on-screen viewing

Star Formation History of Dwarf Galaxies in Cosmological Hydrodynamic Simulations
Kentaro Nagamine, arXiv:0905.1724 [ps, pdf, other]
Comments: 6 pages, 2 figures, Submitted to the special issue on "Dwarf-Galaxy Cosmology," which will be published in the journal "Advances in Astronomy" in December 2009

On the Andromeda to Milky Way mass-ratio
G.C. Baiesi Pillastrini, arXiv:0905.1897 [pdf]
Comments: 8 pages, 2 figures, Accepted for publication in Mon. Not. of Royal Astron. Soc

Despite, or perhaps in spite of, much recent work upping the mass of the Milky Way and the airing of previously unthinkable suggestions that the Milky Way might even be more massive than M31 (Andromeda), this paper concludes that M31 is still the most massive galaxy in the Local Group.

Star Formation in the Central 400 pc of the Milky Way: Evidence for a Population of Massive YSOs
F. Yusef-Zadeh, J. Hewitt, R. G. Arendt, B. Whitney, G. Rieke, M. Wardle, J. L. Hinz, S. Stolovy, C. C. Lang, M. G. Burton, S. Ramirez, arXiv:0905.2161 [pdf, other]
Comments: 89 pages, ten tables, 35 figures, submitted to ApJ

From the abstract: "Within the central 400x50 pc (|l|<1.3\degr and |b|<10') the star formation rate based on the identification of Stage I evolutionary phase of YSO candidates is about 0.14 solar mass/yr. We suggest that a recent burst of star formation took place within the last 10^5 years. This suggestion is also consistent with estimates of star formation rates within the last ~10^7 years showing a peak around 10^5 years ago. "

Global star formation revisited
Joseph Silk, Colin Norman, arXiv:0905.2180 [ps, pdf, other]
Comments: Astrophysical Journal, in press

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Techniques and Software

Estimators for the exponent and upper limit, and goodness-of-fit tests for (truncated) power-law distributions
Thomas Maschberger, Pavel Kroupa, arXiv:0905.0474 [pdf, other]
Comments: 13 pages, MNRAS, in press

Can X-rays provide a solution to the abundance discrepancy problem in photoionised nebulae?
Barbara Ercolano, arXiv:0905.1952 [ps, pdf, other]
Comments: 5 pages, accepted for publication by MNRAS Letters

Drowning in Data : VO to the rescue
A. Lawrence, arXiv:0905.2020 [pdf]
Comments: Published in ".Astronomy: Networked Astronomy and the New Media", 2009, edited by R.J. Simpson, D. Ward-Thompson. Length : 16 pages, 6 figures

From the abstract: "...we can avoid the high energy style of building large fixed hierarchical teams, and keep the individualist style of astronomical research, if the VO is used to build a facility class data infrastructure."

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Stars, Supernovae and Planets

3-D Dynamics of Interactions between Stellar Winds and the Interstellar Medium as Seen by AKARI and Spitzer
Toshiya Ueta, Hideyuki Izumiura, Issei Yamamura, Robert E. Stencel, Yoshikazu Nakada, Mikako Matsuura, Yoshifusa Ita, Toshihiko Tanabe, Hinako Fukushi, Noriyuki Matsunaga, Hiroyuki Mito, Angela K. Speck, arXiv:0905.0756 [ps, pdf, other]
Comments: Invited Talk, to be published in the proceedings of the conference "AKARI, a light to illuminate the misty Universe" held at University of Tokyo, Japan, 16-19 February 2009

The Effect of Different Type Ia Supernova Progenitors on Galactic Chemical Evolution
F. Matteucci, E. Spitoni, S. Recchi, R. Valiante, arXiv:0905.0272 [ps, pdf, other]
Comments: Accepted by A&A

How old are SN Ia Progenitor Systems? New Observational Constraints on the Distribution of Time Delays from GALEX
Kevin Schawinski, arXiv:0905.0850 [ps, pdf, other]
Comments: Accepted for publication in MNRAS

First Stars -- Type Ib Supernovae Connection
Keni'chi Nomoto, Masaomi Tanaka, Yasuomi Kamiya, Nozomu Tominaga, Keiichi Maeda, arXiv:0905.2274 [ps, pdf, other]
Comments: 7 pages, 5 figures
Journal-ref: Proceedings of IAU Symposium No. 255 "Low-Metallicity Star Formation: From the First Stars to Dwarf Galaxies" (2008), eds. L.K. Hunt, S. Madden & R. Schneider (Cambridge University Press), pp. 282-288

The death of massive stars – I. Observational constraints on the progenitors of Type II-P supernovae
S. J. Smartt, J. J. Eldridge, R. M. Crockett, J. R. Maund, 2009, MNRAS, 395, 1409
Full Text: HTML, PDF (Size: 852K)
DOI 10.1111/j.1365-2966.2009.14506.x

Pretty cool. I had no idea that Type II-P core collapse SNe were so common.

Sad news

Professor Martin Turner, DSc, CBE, has passed away. Turner was a major figure in British X-ray astronomy, playing very important roles in the development of the EXOSAT (operational lifetime in orbit 1983-1986), Ginga (1987-1991) and XMM-Newton (1999-now. Turner was PI on the EPIC camera) X-ray Observatories.

Michael Ashley reviews Ian Plimer's "Heaven and Earth"

Michael Ashley, a Professor of Astrophysics as the University of New South Wales, has written a very cogent review of Ian Plimer's "Heaven and Earth," a new book which claims to demolish the argument the scientific consensus that human emissions of CO2 have changed the climate.

Notable points: Plimer believes that the crank paper "The Sun is a plasma diffuser that sorts atoms by mass" accurately describes the Sun. Given the wealth of good popular science and semi-technical literature available on stellar structure and stellar evolution its hard to imagine how a non-astronomer would, in good faith, end up using a relatively obscure crank paper to describe the Sun.

Ashley's final paragraph is worth repeating in its entirety:

Plimer has done an enormous disservice to science, and the dedicated scientists who are trying to understand climate and the influence of humans, by publishing this book. It is not "merely" atmospheric scientists that would have to be wrong for Plimer to be right. It would require a rewriting of biology, geology, physics, oceanography, astronomy and statistics. Plimer's book deserves to languish on the shelves along with similar pseudo-science such as the writings of Immanuel Velikovsky and Erich von Daniken.

2010 NASA science and astrophysics budget requests

Go read Steinn Sigurðsson's post on the Obama administrations budget requests (nb: request, not yet enacted) for NASA's Science Directorate.

Short version: progressively larger cuts for astrophysics in 2010, 2011, 2012 compared to the enacted 2009 budget. Time to start writing letters to your elected representatives...

Manned space program stuff...

John Wilkins at Evolving Thoughts had a post that brought this to my notice:

Now that NASA head Mike Griffin is gone, people are finally able to review the absurdities of the Ares I launcher. I think that the existing heavy launchers will do fine, and that they should develop a very heavy launcher like this.

Work in progress: The unusual starbursting dwarf galaxy NGC 3125

The above image is from an ongoing (*) project I have to study the energy loss via X-ray emission in the dwarf starburst galaxy NGC 3125. This is a representative color image where red is optical H-alpha emission (warm ionized gas at T ~ 10⁴ K), green is soft X-ray emission (E=0.3-2 keV, temperature T ~ a few times 10⁶ K for the diffuse X-ray-emitting gas) and blue is hard X-ray emission (E=2-8 keV, non-thermal emission). The X-ray emission is based on our ~60 ks observation using NASA's Chandra X-ray Observatory, while the H-alpha emission is older ground-based data from Marlowe et al (1995).

The scale bar is an angular scale of 30 arcseconds, which at the distance of NGC 3125 (D=10.5 or 13.8 Mpc) corresponds to a physical size of ~1.5 kpc (about 5000 light years).

Note the faint arcs and filaments of H-alpha emission that extend away from the bright central body of the galaxy - these are unusual for a "normal" galaxy but such large scale H-alpha shells or filaments are indicative of superbubbles or a superwind.

Why am I studying this galaxy? Well, NGC 3125 is a nearby dwarf galaxy with a star formation rate per unit area (SFRI) as intense as the classic starburst superwind galaxy M82, yet with a significantly lower galactic mass (L_K/L_K* ~ 0.03, compared to ~0.5 for M82). The star formation history and properties of the starburst region are known with high confidence. Such a galaxy might be expected to host a powerful superwind that is capable of escaping the galaxy and ejecting a significant fraction of the newly-synthesized heavy elements into the IGM. Indeed the ground-based optical imaging by Marlowe et. al. (1995, ApJ, 438, 563) showed a complex of H-alpha filaments and shells (red in the image above) that is impressive even when compared to famous starbursting dwarfs such as NGC 1569 (which has similar mass and net star formation rate) and NGC 5253. The H-alpha emission is also roughly bipolar, and extended away from the optical body of the galaxy, again suggestive of a wind rather than the roughly spherical shells seen in the lower SFRI/M dwarf starbursts.

Indeed, other "classic" starbursting dwarfs such as NGC 4214 and NGC 4449 lack clear signs of extra-planar H-alpha emission and hence are much poorer examples of probable winds, despite their popularity with observers. This makes NGC 3125 a particularly interesting target in which to study the putative outflows from dwarf starburst galaxies - everyone seems to think of NGC 1569 as typifying a wind from a dwarf, yet it is in reality really unusual. We observed NGC 3125 in the hope that it might be another example of a NGC 1569-like starburst plus outflow.

Superbubbles and superwinds are ultimately driven by the (thermal+ram) pressure of hot (10⁶ ≤ T(K) ≤ 10⁸) SN-heated gas. X-ray observations of these hot plasmas track the radiative energy losses of the hot phases, and hence the energy budget of bubbles and winds. We know the winds in more powerful starbursts like M82 and NGC 3079 are radiatively inefficient (only a few percent of their energy content is radiated away), but its much less clear whether this is true in the weaker bursts in dwarf starburst galaxies. Indeed there is evidence for significant energy loss in some starbursts (work by Calzetti, Harris etc) including a few dwarf starbursts. If bubbles and winds are less energy efficient in dwarf starbursts that might explain why there are so few dwarf starbursts that actually look like they have real winds (i.e. have multi-kpc, open-ended, H-alpha filament complexes and high optical outflow velocities).

Those were the reasons we asked for and were awarded time to observed NGC 3125. We expected to detect more diffuse soft X-ray emission than we ultimately did, and the majority of the X-ray emission from this galaxies comes from two bright point-like X-ray sources which are almost certainly high-mass X-ray binaries. (You can see in the image above the soft X-ray emission has been heavily smoothed in order to make it visible.) The general faintness of the diffuse X-ray emission has somewhat hampered analysis, as the statistical uncertainties associated with spectral analysis are larger and its harder to work out where exactly the X-ray emission is coming from when you have to smooth the images. At this stage all I'd commit to saying is that there is diffuse thermal X-ray emission, although its oddly asymmetric with respect to the H-alpha filaments and its fainter than NGC 1569 would be at that distance. So at one level we do have an answer: NGC 3125 is not "a new NGC 1569," which makes NGC 1569 seem all the more unusual.

Anyway, that is all I'm prepared to say for now, but given that the results appear somewhat interesting I'll probably work on completing the project at some point in the future. Expect to hear more about this odd little galaxy.

(*) The project is ongoing as I still have data analysis to do and more than half the paper left to write up, although the rather small amount of funding we got is totally spent out.

Interesting Astrophysics: Apr 27 to May 01

This week's worth of interesting preprints and papers sports a fine crop of galaxy-related works, many related to starbursts and in three cases (Sato et al; Westmoquette et al; Howk) outflows. There are also two interesting papers on the mysterious hard X-ray emission within our own Galaxy.

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Galaxies and Starbursts

AEGIS: The Nature of the Host Galaxies of Low-Ionization Outflows at z < 0.6
Sato, T; Martin, C.L.; Noeske, K.G.; Koo, D.C.; Lotz, J.M., 2009, ApJ, 696, 214
PDF (1.31 MB) | HTML

The Optical Structure of the Starburst Galaxy M82. I. Dynamics of the Disk and Inner-Wind
Westmoquette, M.S.; Smith, L.J.; Gallagher, J.S.; Trancho, G.; Bastian, N.; Konstantopoulos, I. S., 2009, ApJ, 696, 192
PDF (2.04 MB) | HTML

Deep V and K band photometry of the host galaxy of Haro 11
Genoveva Micheva, Erik Zackrisson, Göran Östlin, Nils Bergvall, arXiv:0904.4502 [pdf]
Comments: 6 pages, 4 figures, to be published in conference proceedings of "Star-forming Dwarf Galaxies: Ariadne's Thread in the Cosmic Labyrinth", Crete, Greece, in Physica Scripta

Resolving the molecular environment of Super Star Clusters in Henize 2-10
G. Santangelo, L. Testi, L. Gregorini, S. Leurini, L. Vanzi, C.M. Walmsley, D.J. Wilner, arXiv:0904.4784 [ps, pdf, other]
Comments: 10 pages, 7 figures, 3 tables; Accepted for publication in Astronomy and Astrophysics

The H alpha Galaxy Survey VII. The spatial distribution of star formation within disks and bulges
P. A. James, C. F. Bretherton, J. H. Knapen, arXiv:0904.4261 [ps, pdf, other]

Comments: 15 pages, accepted for publication by Astronomy and Astrophysics. See also arXiv:0904.4263

The H alpha Galaxy Survey. VIII. Close companions and interactions, and the definition of starbursts
Johan H. Knapen, Philip A. James, arXiv:0904.4263 [ps, pdf, other]
Comments: ApJ, in press (June 20, 2009 issue). With HaGS Paper VII (James, Bretherton, and Knapen 2009, arXiv:0904.4261), this paper concludes the H alpha Galaxy Survey

Worth a closer look. From the abstract: "We conclude that no one starburst definition can be devised which is objective and generally discriminant. Unless one restricts the use of the term "starburst" to a very small number of galaxies, the term will continue to be used for a heterogeneous and wide-ranging collection of objects with no physical basis for their classification as starburst."

GOALS: The Great Observatories All-Sky LIRG Survey
L. Armus, et al, arXiv:0904.4498 [ps, pdf, other]
Comments: 17 pages, 2 tables, 7 postscript figures. Accepted for publication in PASP

Neat.

Spitzer IRS observations of k+a galaxies: A link between PAH emission properties and AGN feedback?
I. G. Roseboom, S. Oliver, D. Farrah, arXiv:0904.4410 [ps, pdf, other]
Comments: 13 pages, 3 figures, accepted for publication in ApjL

Spectral Energy Distribution Fitting: Application to Lyman Alpha-Emitting Galaxies
Eric Gawiser, arXiv:0904.3798 [ps, pdf, other]

Comments: A review and discussion from the "Understanding Lyman-alpha Emitters" meeting in Heidelberg, Oct. 2008, 10 pages, to be published in New Astronomy Reviews. Ful
conference summary available as arXiv:0904.3335. Conference home-page, with presentations, is this http URL

From the abstract: "Lyman Alpha-emitter SED fitting results from the literature find star formation rates ~3 M_sun/yr, stellar masses ~10^9 M_sun for the general population but ~10^10 M_sun for the subset detected by IRAC, and very low dust extinction, A_V < 0.3, although a couple of outlying analyses prefer significantly more dust and higher intrinsic star formation rates."

Ram pressure stripping of tilted galaxies
P. Jachym, J. Koppen, J. Palous, F. Combes, arXiv:0904.3886 [ps, pdf, other]

Extraplanar Dust in Spiral Galaxies: Tracing Outflows in the Disk-Halo Interface
J. Christopher Howk, arXiv:0904.4928 [ps, pdf, other]

Comments: 8 pages; Invited review for the proceedings of "The Role of Disk-Halo Interaction in Galaxy Evolution: Outflow vs. Infall?" (Ed. M. de Avillez), in Espinho, Portugal, 18-22 August 2008 ; high resolution version at this http URL

Structures of Local Galaxies Compared to High Redshift Star-forming Galaxies
Sara M. Petty, Duilia F. de Mello, John S. Gallagher III, Jonathan P. Gardner, Jennifer M. Lotz, C. Matt Mountain, Linda J. Smith, arXiv:0904.4433 [ps, pdf, other]
Comments: Submitted to the Astronomical Journal after responding to referee comments

An interesting experiment, and one that does not reassure me that the apparent morphologies of high red-shift galaxies are always accurately determined.

An X-Ray Face-on View of the Sgr B Molecular Clouds Observed with Suzaku
Syukyo G. Ryu, Katsuji Koyama, Masayoshi Nobukawa, Ryosuke Fukuoka, Takeshi Go Tsuru, arXiv:0904.4550 [ps, pdf, other]
Comments: 11 pages, 8 figures, accepted for publication in PASJ (Publications of the Astronomical Society of Japan)

Discrete sources as the origin of the Galactic X-ray ridge emission
Revnivtsev M., Sazonov S., Churazov E., Forman W., Vikhlinin A., Sunyaev R., arXiv:0904.4649 [ps, pdf, other]
Comments: 16 pages, 3 figures. Draft version of the paper that will appear in Nature, Issue April 30, 2009

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Stars, Supernovae and Planets

X-rays from the explosion site: Fifteen years of light curves of SN 1993J
Poonam Chandra, Vikram V. Dwarkadas, Alak Ray, Stefan Immler, David Pooley, arXiv:0904.3955 [ps, pdf, other]
Comments: 33 pages, 8 figures, Accepted for publication in Astrophysical Journal

Hydrodynamic simulations of the core helium flash
M.Mocak, E.Mueller, A.Weiss, K.Kifonidis, arXiv:0904.4867 [pdf, other]
Comments: 6 pages, 5 figures. IAUS 252 Conference Proceeding (Sanya, China): "The art of modeling stars in the 21st century" Journal-ref: 2008IAUS..252..215M

On the correlation between metallicity and the presence of giant planets
M. Haywood, arXiv:0904.4445 [ps, pdf, other]
Comments: Accepted in ApJL

Argues that the correlation between stellar metallicity and the presence of giant planets is NOT explained by the well-publicized hypothesis that the planet formation probability is increased in stellar disks with higher metallicities. I have no idea how the planet formation community will view this paper.