Highlights - Volume 494-2 (February I 2009)
- Published on 03 February 2009
|HIGHLIGHTS: this week in A&A
Volume 494-2 (February I 2009)
|In section 6. Interstellar and circumstellar matter
“A spatially resolved study of photoelectric heating and [C II] cooling in the LMC. Comparison with dust emission as seen by SAGE”, D. Rubin, S. Hony, S. C. Madden et al., A&A 494, p. 647
The Large Magellanic Cloud (LMC) is an obvious site for studying the properties of the interstellar medium in a galaxy with lower metallicity than the Milky Way. In this paper, Rubin et al. measure the photoelectric efficiency (or heating efficiency) of LMC grains combining the Mochizuki et al. [CII] 157 μm observations with the recent Meixner et al. SAGE FIR survey using the SPITZER telescope. They find a good correlation between the two, suggesting that PAH photoelectron emission is the dominant heating process.
In section 1. Letters to the Editor. Sub-section 4. Extragalactic astronomy
|In section 4. Extragalactic astronomy
“The physical properties of Ly alpha emitting galaxies: not just primeval galaxies?”, by L. Pentericci, A. Grazian, A. Fontana et al., A&A 494, p. 553
Pushing the search for the most distant galaxies is now a central challenge for present-day cosmology. These elusive and very faint objects located at the border of the visible universe are difficult to find and extensive observational campaigns using the most advanced ground-based and space-borne telescopes are required. This paper uses data from one of the largest international coordinated efforts (GOODS) to shed light on the origin, properties, and relationship of the two most common high-redshift galaxy populations, the so-called Lyman Alpha emitters and the Lyman break galaxies. Somewhat surprisingly, although not completely unexpected, the authors show that at least some of these remote objects are not young, but instead contain traces of stellar populations older than one billion years, thus pushing the epoch of first star formation even farther back in time. In addition, evidence is reported for the most massive among these objects to be dust-enriched, demonstrating that dust grains formed quite rapidly during cosmic evolution.
© Astronomy & Astrophysics 2009