Related papers: Origin and Status of Low-Mass Candidate Hyperveloc…
Hypervelocity stars (HVS) move so fast that they are unbound to the Galaxy. When they were first discovered in 2005, dynamical ejection from the supermassive black hole (SMBH) in the Galactic Centre (GC) was suggested as their origin. The…
We assemble a large sample of 12,784 high-velocity stars with total velocity $\it{V}_{\rm{GSR}}\ge {\rm 300}$ km s$^{-1}$, selected from RAVE DR5, SDSS DR12, LAMOST DR8, APOGEE DR16, GALAH DR2, and $Gaia$ EDR3. In this sample, 52 are…
Little is known about the origin of the fastest stars in the Galaxy. Our understanding of the Milky Way and surrounding dwarf galaxies chemical evolution history allows us to use the chemical composition of a star to investigate its origin,…
Context: Hyper-velocity stars are suggested to originate from the dynamical interaction of binary stars with the supermassive black hole in the Galactic centre (GC), which accelerates one component of the binary to beyond the Galactic…
Two decades on, the study of hypervelocity stars is still in its infancy. These stars can provide novel constraints on the total mass of the Galaxy and its Dark Matter distribution. However how these stars are accelerated to such high…
The fastest moving stars provide insight into several fundamental properties of the Galaxy, including the escape velocity as a function of Galactocentric radius, the total mass, and the nature and frequency of stellar encounters with the…
Based on the second Gaia data (Gaia DR2) and spectroscopy from the LAMOST Data Release 5, we defined the high-velocity (HiVel) stars sample as those stars with $v_{\mathrm{gc}} > 0.85 v_{\mathrm{esc}}$, and derived the final sample of 24…
Hypervelocity stars are those that have speeds exceeding the escape speed and are hence unbound from the Milky Way. We investigate a sample of low-mass hypervelocity candidates obtained using data from the high-precision SDSS Stripe 82…
Photospheric abundances are presented for 27 elements from carbon to europium in 181 F-G dwarfs from a differential LTE analysis of high-resolution and high signal-to-noise spectra. Stellar $T_{\rm eff}$ were adopted from an infrared flux…
Low-mass, variable, high-velocity stars are interesting study cases for many aspects of Galactic structure and evolution. Until recently, the only known high- or hyper-velocity stars were young stars thought to originate from the Galactic…
We present chemical abundances of 57 metal-poor stars that are likely constituents of the outer stellar halo in the Milky Way. Almost all of the sample stars have an orbit reaching a maximum vertical distance (Z_max) of >5 kpc above and…
Hypervelocity stars (HVSs) travel so fast that they may leave the Galaxy. The tidal disruption of a binary system by the supermassive black hole in the Galactic center is widely assumed to be their ejection mechanism. To test the hypothesis…
We aim to quantify the chemical and kinematical properties of the Galactic disks with a sample of 119,558 giant stars having abundances and 3D velocities taken or derived from the APOGEE DR17 and Gaia EDR3 catalogs. The Gaussian Mixture…
In recent years surveys have identified several dozen B stars in the Milky Way halo moving faster than the local escape speed. The origin of most of these hypervelocity stars (HVSs) is still poorly constrained. Here we show that the…
In this paper, we report 591 high velocity star candidates (HiVelSCs) selected from over 10 million spectra of the data release seven (DR7) of the Large Sky Area Multi-object Fiber Spectroscopic Telescope and the second Gaia data release,…
We present the abundance analysis of 97 nearby metal-poor (-3.3<[Fe/H]<-0.5) stars having kinematics characteristics of the Milky Way (MW) thick disk, inner, and outer stellar halos. The high-resolution, high-signal-to-noise optical spectra…
We combine the estimated metallicities [Fe/H], abundances [\alpha/Fe], positions and motions of a sample of 27,500 local (7<R/kpc<9, 0.5<|z|/kpc<2.5) SDSS/SEGUE G-type dwarf stars to investigate the chemo-orbital properties of the Milky…
The study of the Milky Way stellar discs in the context of galaxy formation is discussed. In particular we explore the properties of the Milky Way disc using a new sample of about 550 dwarf stars for which we have recently obtained…
Hypervelocity stars (HVSs) are stars ejected from the Galactic Centre (GC) through tidal interactions with the central supermassive black hole. Formed in the immediate vicinity of Sgr~A$^\ast$, these stars are accelerated to velocities high…
We determined the ages, the kinematic parameters and Galactic orbital parameters of six metal-poor (-2.4<[Fe/H]<-1 dex) F-type high proper motion (HPM) stars to investigate their HPM nature and origin. For the kinematical procedure, the…