相关论文: Molecular Gas in the Galactic Halo and Beyond

Significant progress has been made over the last few years to explore the gaseous halo of the Milky Way by way of absorption spectroscopy. I review recent results on absorption line studies in the halo using various instruments, such as the…

In this article I review recent observations of the gaseous halos of galaxies and the intergalactic medium at low redshift. In the first part I discuss distribution, metal content, and physical properties of the Galactic intermediate- and…

More than 20 years after the Copernicus satellite, ORFEUS allows the investigation of molecular hydrogen (H_2) in the diffuse interstellar medium by way of FUV absorption spectroscopy once again. This time, targets in the Magellanic Clouds…

We perform a systematic study of physical properties and distribution of neutral and ionised gas in the halo of the Milky Way (MW). Beside the large neutral intermediate- and high-velocity cloud (IVC, HVC) complexes there exists a…

Recent spectroscopic observations of intermediate- and high-velocity clouds (IVCs and HVCs) in the Milky Way halo have unveiled the presence of diffuse interstellar molecular hydrogen (H_2) several kpc away from the Galactic disk. Most of…

We investigate interstellar absorption from molecular hydrogen (H_2) and metals in an intermediate-velocity cloud (IVC) in the direction of the LMC star Sk -68 80 (HD 36521), based on data from the Far Ultraviolet Spectroscopic Explorer…

Far Ultraviolet Spectroscopic Explorer (FUSE) data is used to investigate the molecular hydrogen (H_2) content of intermediate-velocity clouds (IVCs) in the lower halo of the Milky Way. We analyze interstellar absorption towards 56 (mostly…

The recent observations of microlensing events in the LMC by the MACHO and EROS collaborations suggest that an important fraction of the galactic halo is in the form of Massive Halo Objects (MHO) of about 0.1 M_{\odot}. Here, we argue that…

Recent observations of microlensing events in the Large Magellanic Cloud suggest that a sizeable fraction of the galactic halo is in form of MACHOs with mass less than abou 0.1 M_{\odot}. Here we argue that molecular clouds (mainly H_2)…

We know little about the outermost portions of galaxies because there is little light coming from them. We do know that in many cases atomic hydrogen (HI) extends well beyond the optical radius \cite{Casertano91}. In the centers of…

In 1998 several papers claim the detection of an ubiquitous gaseous phase within the Galactic halo. Here we like to focus on the detections of X-ray emitting gas within the Galactic halo as well as the discovery of a pervasive neutral…

Molecular hydrogen (H$_2$) is by far the most abundant molecule in the Universe. However, due to the low emissivity of H$_2$, carbon monoxide (CO) is widely used instead to trace molecular gas in galaxies. The relative abundances of these…

We report the discovery of molecular hydrogen absorption in a Galactic high-velocity cloud (HVC) in the direction of the Large Magellanic Cloud. For the same HVC we derive an iron abundance which is half of the solar value. Thus, all…

Molecular hydrogen clouds can contribute substantially to the galactic halo< dark matter and may lead to the birth of massive halo objects (MHOs) observed indirectly by microlensing. We present a method to detect these molecular clouds in…

We describe a moderate-resolution FUSE mini-survey of H2 in the Milky Way and Magellanic Clouds, using four hot stars and four AGN as background sources. FUSE spectra of nearly every stellar and extragalactic source exhibit numerous…

This work presents a new detection of H$_2$ absorption arising in a high velocity cloud (HVC) associated with either the Milky Way or the Large Magellanic Cloud (LMC). The absorber was found in an archival Far Ultraviolet Spectroscopic…

I review studies of the hot gaseous medium in and around nearby normal disk galaxies, including the Milky Way. This medium represents a reservoir of materials required for lasting star formation, a depository of galactic feedback (e.g.,…

We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of interstellar molecular hydrogen (H_2) in two Galactic high-velocity clouds (HVCs). Molecular hydrogen absorption is detected in the Magellanic Stream (abundance ~0.3…

To explore the origin of high-velocity gas in the direction of the Large Magellanic Cloud (LMC) we analyze absorption lines in the ultraviolet spectrum of a Galactic halo star that is located in front of the LMC at d=9.2 kpc distance. We…

We use archival UV absorption-line data from HST/STIS to statistically analyse the absorption characteristics of the high-velocity clouds (HVCs) in the Galactic halo towards more than 40 extragalactic background sources. We determine…