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We employ three-band Spitzer-MIPS observations to search for cold dust emission in three neutral hydrogen compact high-velocity clouds (CHVCs) in the vicinity of the Milky Way. Far-infrared emission correlated with HI column density was…

星系天体物理 · 物理学 2012-03-06 Rik J. Williams , Smita Mathur , Shawn Poindexter , Martin Elvis , Fabrizio Nicastro

The Galactic Anticenter Stellar Structure (GASS) has been identified with excess surface densities of field stars in several large area sky surveys, and with an unusual, string-like grouping of star clusters. Some members of the cluster…

We present medium-resolution, near-ultraviolet VLT/FLAMES observations of the star USNO-A0600-15865535. We adapt a standard method of stellar typing to our measurement of the shape of the Balmer epsilon absorption line to demonstrates that…

星系天体物理 · 物理学 2016-09-21 J. E. G. Peek , Rongmon Bordoloi , Hugues Sana , Julia Roman-Duval , Jason Tumlinson , Yong Zheng

High-Velocity Clouds (HVCs) are a major fuel reservoir for star formation in the Galactic disk. Determining their origin and kinematics is thus crucial for understanding Galactic evolution. In this paper, we employ simple test-particle…

星系天体物理 · 物理学 2026-04-28 Izumi Seno , Shu-ichiro Inutsuka , Jiro Shimoda

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…

天体物理学 · 物理学 2007-05-23 Philipp Richter

The neutral hydrogen structure of high-velocity cloud A0 (at about -180 km/s) has been mapped with a 9.1 arcmin resolution. Gaussian decomposition of the profiles is used to separately map families of components defined by similarities in…

星系天体物理 · 物理学 2015-06-15 Gerrit L. Verschuur

We consider here the class of compact, isolated, high-velocity HI clouds, CHVCs, which are sharply bounded in angular extent down to a limiting column density of 1.5x10^18 cm^-2. We describe our automated search algorithm and it's…

天体物理学 · 物理学 2007-05-23 W. B. Burton , R. Braun , V. de Heij

Optical emission lines provide an important new window on the HVCs. Recent studies of the H-alpha line reveal that ionized gas is pervasively associated with the neutral hydrogen in HVCs. The Wisconsin H-Alpha Mapper (WHAM) instrument has…

天体物理学 · 物理学 2007-05-23 S. L. Tufte , R. J. Reynolds , L. M. Haffner

Ten isolated compact high-velocity clouds (CHVCs) of the type cataloged by Braun & Burton (1999) have been imaged with the Arecibo telescope and were found to have a nested core/halo morphology. We argue that a combination of…

天体物理学 · 物理学 2009-11-06 W. B. Burton , R. Braun , J. N. Chengalur

We study the properties of all major HVC complexes from a sample compiled 1991 by Wakker & van Woerden (WvW). We use the Leiden/Argentine/Bonn all sky 21-cm line survey and decompose the profiles into Gaussian components. We find a well…

天体物理学 · 物理学 2009-11-11 Peter M. W. Kalberla , Urmas Haud

Hypervelocity stars (HVSs) are stars ejected completely out of the Milky Way by three-body interactions with the massive black hole in the Galactic center. We describe 643 new spectroscopic observations from our targeted survey for HVSs. We…

The discovery of an HI cloud with peculiar properties at equatorial coordinates (J2000) ra=07h49m, dec=04d30m is presented. The HI object was detected at 21cm using the 300-m NAIC Arecibo telescope. Subsequent follow-up high-resolution…

天体物理学 · 物理学 2009-11-13 L. Dedes , C. Dedes , P. W. M Kalberla

The bulk flow velocity for the cluster of interstellar cloudlets within about 30 pc of the Sun is determined from optical and ultraviolet absorption line data, after omitting from the sample stars with circumstellar disks or variable…

天体物理学 · 物理学 2009-11-07 P. C. Frisch , L. Grodnicki , D. E. Welty

We have undertaken high-resolution follow-up of a sample of high velocity HI clouds apparently associated with M31. Our sample was chosen from the population of high-velocity clouds (HVCs) detected out to 50 kpc projected radius of the…

天体物理学 · 物理学 2009-11-10 T. Westmeier , R. Braun , D. Thilker

Complex A is a high-velocity cloud that is traversing through the Galactic halo toward the Milky Way's disk. We combine both new and archival Green Bank Telescope observations to construct a spectroscopically resolved HI~21-cm map of this…

We present the current distance estimates to 11 intermediate velocity clouds (IVCs) which are part of the David Dunlap Observatory Intermediate Velocity Cloud (DDO IVC) Distance Project (Clarke et al. 1999). We briefly discuss constraints…

天体物理学 · 物理学 2007-05-23 T. E. Clarke , M. Gladders , G. Mallen-Ornelas

In the spectra of 139 early-type Large Magellanic Cloud (LMC) stars observed with FUSE and with deep radio Parkes HI 21-cm observations along those stars, we search for and analyze the absorption and emission from high-velocity gas at…

星系天体物理 · 物理学 2009-08-24 N. Lehner , L. Staveley-Smith , J. C. Howk

Six examples of the compact, isolated high-velocity HI clouds (CHVCs) identified by Braun and Burton (1999) have been imaged with the WSRT. The 65 confirmed objects in this class define a dynamically cold system, with a global minimum for…

天体物理学 · 物理学 2007-05-23 Robert Braun , Butler Burton

We have mapped 11 compact high-velocity clouds (CHVCs) in the 21-cm line emission of neutral, atomic hydrogen, using the Effelsberg 100-m radio telescope. The aim of our observations was to study the overall distribution of the warm neutral…

天体物理学 · 物理学 2009-11-10 T. Westmeier , C. Bruens , J. Kerp

We report the first high-sensitivity HI observation toward the spiral galaxy M94 with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). From these observations, we discovered that M94 has a very extended HI disk, twice…

星系天体物理 · 物理学 2023-08-02 Ruilei Zhou , Ming Zhu , Yanbin Yang , Haiyang Yu , Lixia Yuan , Peng Jiang , Wenzhe Xi