Deep HI observations of the compact high-velocity cloud HVC 125+41-207

Citation
C. Bruns et al., Deep HI observations of the compact high-velocity cloud HVC 125+41-207, ASTRON ASTR, 370(1), 2001, pp. L26-L30
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
0004-6361 → ACNP
Volume
370
Issue
1
Year of publication
2001
Pages
L26 - L30
Database
ISI
SICI code
0004-6361(200104)370:1<L26:DHOOTC>2.0.ZU;2-4
Abstract
We present deep HI observations of the compact high-velocity cloud HVC 12541-207 using the 100-m Effelsberg telescope. Our goal was in particular to study the warm neutral medium (WNM) in detail. The Effelsberg data reveals a two phase core/halo structure - one component with a velocity width of FW HM approximate to 5 km s(-1) (Westerbork data show FWHM approximate to 2 km s(-1), Braun & Burton 2000) and one with FWHM approximate to 18 km s(-1). The column density distribution of the warmer component is highly asymmetri c and shows a head-tail structure. We performed a Gaussian decomposition of tile cloud and found that 52%, of the HI mass of the cloud is in the WNM. 24% of the WNM is located in tile tail. The overall structure and the syste matic variation of the observational parameters radial velocity, velocity d ispersion and column density indicate that this cloud is currently interact ing with the ambient medium. The Westerbork HI data of this HVC (Braun Sr B urton 2000) reveals an interesting dense condensation. Assuming that this c ondensation is virialized and in pressure equilibrium with the ambient medi um, we derive a distance of 130 kpc for HVC 125+41-207. Following these con siderations, it is possible to constrain the parameters n(IGM) < 7.8 10(-6) cm(-3) and T-IGM > 1.1 10(5) K of the intergalactic medium of the Local Gr oup.