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Highlights - Volume 482-3 (May II 2008)

Details: Published on 21 April 2008

HIGHLIGHTS: this week in A&A

Volume 482-3 (May II 2008)

In section 1. Letters

“Detection of hot gas in the filament connecting the clusters of galaxies Abell 222 and Abell 223”, by N. Werner et al., A&A 482, p. L29

The theoretically derived notion that most of the baryonic matter of the universe is presently found in the rarefied gas between galaxies, i.e. the intergalactic medium, is now widely accepted. Such gas is gravitationally heated during the ongoing process of cosmic structure formation to temperatures of about a million degrees, hence identifying this component as the "warm-hot" intergalactic medium, or WHIM. This paper presents the detection of a WHIM filamentary structure connecting a pair of clusters of galaxies, thus reporting one of the most convincing X-ray proofs of the network of filaments tracing the so-called "cosmic web". In addition, this discovery strongly supports the theoretical prediction that most of the cosmic gas currently resides outside galaxies.

In section 1. Letters

“First detection of CO in a high-redshift damped Lyman-a system”, by R. Srianand et al., A&A 482, p. L39

The authors report the first detection of the CO molecule in a high-redshift (z=2.42) damped Lyman-a system. The CO/H2 ratio is 3 10-6, much lower than the usual ratio in dense molecular clouds, but typical of translucent clouds in the Milky Way. Since the gas is diffuse, the H2 density is not high enough to excite the rotational levels of CO, which is then only excited by the cosmic background radiation. The measured CO excitation temperature leads to a precise determination of TCMB at this redshift, in perfect agreement with the Big-Bang theory.

“Transiting exoplanets from the CoRoT space mission. I. CoRoT-exo-1b: a low-density short-period planet around a G0V star”, by P. Barge et al., A&A 482, p. L17

Of all extrasolar planets, the few dozen that occult their parent star once each orbit are of particular interest, since their radius can be measured in addition to their mass. The COROT satellite was launched to identify such transiting systems, with a sensitivity goal that allows detecting planets only twice as large as the Earth. The paper presents its first results after a preliminary analysis of early data: detection of. a Jupiter-mass planet.