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The Milky Way halo is one of the few galactic haloes that provides a unique insight into galaxy formation by resolved stellar populations. Here, we present a catalogue of $\sim$47 million halo stars selected independent of parallax and…

We report the discovery of three HI absorbers toward low-power radio active galactic nuclei (AGNs) in a pilot HI absorption survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Compared to past studies, FAST…

Astrophysics of Galaxies · Physics 2023-08-04 Qingzheng Yu , Taotao Fang , Junfeng Wang , Jianfeng Wu

We use the HST ACS imaging of the two GOODS fields during Cycles 11, 12, and 13 to derive the Type Ia supernova rate in four redshift intervals in the range 0.2<z<1.8. Compared to our previous results based on Cycle 11 observations only, we…

Astrophysics · Physics 2009-11-13 Tomas Dahlen , Louis-Gregory Strolger , Adam G. Riess

We present the first subarcsecond submillimeter images of the enigmatic ultracompact HII region (UCHII) G5.89-0.39. Observed with the SMA, the 875 micron continuum emission exhibits a shell-like morphology similar to longer wavelengths. By…

Astrophysics · Physics 2015-03-30 T. R. Hunter , C. L. Brogan , R. Indebetouw , C. J. Cyganowski

We describe algorithms that detect 21cm line HI self-absorption (HISA) in large data sets and extract it for analysis. Our search method identifies HISA as spatially and spectrally confined dark HI features that appear as negative residuals…

VLA and Parkes 64 m radiotelescope 21-cm observations of the starburst dwarf galaxy NGC 5253 reveal a multi-component non-axisymmetric HI distribution. The component associated with the stellar body shows evidence for a small amount of…

Astrophysics · Physics 2009-11-13 Henry A. Kobulnicky , Evan. D. Skillman

Modern theories of galaxy formation predict that the Galactic stellar halo was hierarchically assembled from the accretion and disruption of smaller systems. This hierarchical assembly is expected to produce a high degree of structure in…

The direct detection of a stellar system that explodes as a Type Ia supernova (SN Ia) has not yet been successful. Various indirect methods have been used to investigate SN Ia progenitor systems but none have produced conclusive results. A…

Solar and Stellar Astrophysics · Physics 2016-03-09 Kate Maguire , Stefan Taubenberger , Mark Sullivan , Paolo A. Mazzali

We present the first systematic study of bipolar outflows using HC$_3$N as a tracer in a sample of 146 massive star-forming regions from ALMA-ATOMS survey. Protostellar outflows arise at the initial stage of star formation as a consequence…

We present in this paper mid-infrared (5-8~$\mu$m) spectroscopy toward the massive young binary W3~IRS~5, using the EXES spectrometer in high-resolution mode ($R\sim$50,000) from the NASA Stratospheric Observatory for Infrared Astronomy…

Hypervelocity stars (HVSs) are stars which have been ejected from the Galactic Centre (GC) at velocities of up to a few thousand km/s. They are tracers of the Galactic potential and can be used to infer properties of the GC, such as the…

We explore the effect of using different kinematic tracers (HI and H$\alpha$) on reconstructing the encounter parameters of the Mice major galaxy merger (NGC 4676A/B). We observed the Mice using the SparsePak Integral Field Unit (IFU) on…

Astrophysics of Galaxies · Physics 2017-12-27 S. Alireza Mortazavi , Jennifer M. Lotz , Joshua E. Barnes , George C. Privon , Gregory F. Snyder

We present VLA HI spectral line imaging of 5 sources discovered by ALFALFA. These targets are drawn from a larger sample of systems that were not uniquely identified with optical counterparts during ALFALFA processing, and as such have…

With new atomic-hydrogen (HI) observations of FAST Extended Atlas of Selected Targets Survey (FEASTS), we present the first statistical comparison of HI morphology between observations and cosmological simulations, focusing on low-column…

Astrophysics of Galaxies · Physics 2026-02-04 Xuchen Lin , Jing Wang , Guinevere Kauffmann , Volker Springel , Rüdiger Pakmor

The detection and characterization of accretion processes in the disks surrounding young stars may be directly relevant to studies of planet formation. Especially the study of systems with very low accretion rates (<< 10^{-10} M_sun…

Astrophysics · Physics 2009-11-10 M. E. van den Ancker

We study the properties of low-column density gas clumps in the halo of the Milky Way based on high-resolution 21-cm observations. Using interferometric data from the WSRT and the VLA we study HI emission at low-, intermediate- and high…

Astrophysics of Galaxies · Physics 2015-05-13 N. Ben Bekhti , P. Richter , B. Winkel , F. Kenn , T. Westmeier

Time-domain spectroscopy of the classical accreting T Tauri star, TW Hya, covering a decade and spanning the far UV to the near-infrared spectral regions can identify the radiation sources, the atmospheric structure produced by…

Solar and Stellar Astrophysics · Physics 2015-06-19 A. K. Dupree , N. S. Brickhouse , S. R. Cranmer , P. Berlind , J. Strader , G. H. Smith

With a goal toward deriving the physical conditions in external galaxies, we present a study of the ammonia (NH$_3$) emission and absorption in a sample of star forming systems. Using the unique sensitivities to kinetic temperature afforded…

HH 223 is the optical counterpart of a larger scale H2 outflow, driven by the protostellar source VLA 2A, in L723. Its poorly collimated and rather chaotic morphology suggested the Integral Field Spectroscopy (IFS) as an appropriate option…

Astrophysics of Galaxies · Physics 2015-06-05 R. López , B. García-Lorenzo , R. Estalella , A. Riera , C. Carrasco-González , G. Gómez