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200 papers

We present a comprehensive and precise description of the Sagittarius (Sgr) stellar stream's 3D geometry as traced by its old stellar population. This analysis draws on the sample of ${\sim}44,000$ RR Lyrae (RRab) stars from the Pan-STARRS1…

We have assembled a large-area spectroscopic survey of giant stars in the Sagittarius (Sgr) dwarf galaxy core. Using medium resolution (R ~15,000), multifiber spectroscopy we have measured velocities of these stars, which extend up to 12…

Stellar halo substructures were identified using statistical photometric parallax of blue main sequence turnoff stars from fourteen Sloan Digital Sky Survey stripes in the north Galactic cap. Four structures are consistent with previous…

Astrophysics of Galaxies · Physics 2018-10-31 Jake Weiss , Heidi Jo Newberg , Travis Desell

We describe first results of a spectroscopic probe of selected fields from the Grid Giant Star Survey. Multifiber spectroscopy of several hundred stars in a strip of eleven fields along delta approximately -17^{circ}, in the range 12 <~…

An all high-latitude sky survey for cool carbon giant stars in the Galactic halo has revealed 75 such stars, of which the majority are new detections. Of these, more than half are clustered on a Great Circle on the sky which intersects the…

Astrophysics · Physics 2009-10-31 Rodrigo Ibata , Geraint F. Lewis , Michael Irwin , Edward Totten , Thomas Quinn

This study presents a tomographic survey of a subset of the outer halo (10-40 kpc) drawn from the Sloan Digital Sky Survey Data Release 6. Halo substructure on spatial scales of $>3$ degrees is revealed as an excess in the local density of…

Astrophysics of Galaxies · Physics 2015-05-14 Stefan C. Keller

Two studies have recently reported the discovery of pronounced Halo substructure in the Sloan Digital Sky Survey (SDSS) commissioning data. Here we show that this Halo substructure is almost in its entirety due to the expected tidal stream…

Astrophysics · Physics 2009-05-29 Rodrigo Ibata , Michael Irwin , Geraint Lewis , Andrea Stolte

Using proper motions from Gaia Early Data Release 3 (Gaia EDR 3) and radial velocities from several surveys, we identify 60 candidate high-velocity stars with total velocity greater than 75\% escape velocity that probably origin from…

Astrophysics of Galaxies · Physics 2022-07-06 Hefan Li , Cuihua Du , Jun Ma , Jianrong Shi , Heidi Jo Newberg , Yunsong Piao

There are expected to be physical relationships between the globular clusters (GCs) and stellar substructures in the Milky Way, not all of which have yet been found. We search for such substructures from a combined halo sample of SDSS blue…

Astrophysics of Galaxies · Physics 2020-08-05 Zhen Yuan , Jiang Chang , Timothy C. Beers , Yang Huang

We reconsider the case for the association of Galactic globular clusters (GCs) to the tidal stream of the Sagittarius dwarf spheroidal galaxy (Sgr dSph), using Gaia DR2 data. We use RR Lyrae to trace the stream in 6D and we select clusters…

Astrophysics of Galaxies · Physics 2020-05-06 M. Bellazzini , R. Ibata , K. Malhan , N. Martin , B. Famaey , G. Thomas

It is now known that minor mergers are capable of creating structure in the phase-space distribution of their host galaxy's disc. In order to search for such imprints in the Milky Way, we analyse the SEGUE F/G-dwarf and the Schuster et al.…

Tidally disrupted globular cluster streams are usually observed, and therefore perceived, as narrow, linear and one-dimensional structures in the 6D phase-space. Here we show that the GD-1 stellar stream ($\approx$ 30 pc wide), which is the…

Astrophysics of Galaxies · Physics 2019-08-23 Khyati Malhan , Rodrigo A. Ibata , Raymond G. Carlberg , Monica Valluri , Katherine Freese

We report the identification of extended tidal debris potentially associated with the globular cluster NGC 3201, using the RAVE catalogue. We find the debris stars are located at a distance range of 1-7 kpc based on the forthcoming RAVE…

The potential association of the globular cluster (GC) NGC 4147 with the Sagittarius (Sgr) dwarf spheroidal galaxy has been proposed due to their comparable locations and radial velocities. However, there are still debates about this…

Astrophysics of Galaxies · Physics 2024-10-28 YingHua Zhang , Jundan Nie , Hao Tian , Chao Liu

It is still unclear whether the Sagittarius spiral arm is a major spiral arm in the Galaxy or whether it just outlines a region of enhanced star formation because of the local compression of gas. The best way to separate these scenarios out…

Astrophysics of Galaxies · Physics 2016-01-13 Preben Grosbøl

We present the results of a spectroscopic survey performed in the outskirts of the globular cluster NGC1851 with VIMOS@VLT. The radial velocities of 107 stars in a region between 12' and 33' around the cluster have been derived. We clearly…

Using deep photometric data from CFHT/Megacam, we study the morphology and density of the GD-1 stream, one of the longest and coldest stellar streams in the Milky Way. Our deep data recovers the lower main sequence of the stream with…

Astrophysics of Galaxies · Physics 2018-03-28 T. J. L. de Boer , V. Belokurov , S. E. Koposov , L. Ferrarese , D. Erkal , P. Cote , J. F. Navarro

This is the second paper in a series, which studies the likelihood that some globular clusters (GCs) of the Milky Way (MW) could have originated from a dwarf satellite galaxy (DSG). Using a large suite of three-body simulations we determine…

Astrophysics of Galaxies · Physics 2023-10-30 Ali Rostami Shirazi , Pouria Khalaj , Hosein Haghi

We present a maximum likelihood method for determining the spatial properties of tidal debris and of the Galactic spheroid. With this method we characterize Sagittarius debris using stars with the colors of blue F turnoff stars in SDSS…

Sagittarius A*, the super-massive black hole at the center of the Milky Way, is surrounded by a small cluster of high velocity stars, known as the S-stars. We aim to constrain the amount and nature of stellar and dark mass associated with…