High-velocity Stars in SDSS/APOGEE DR17

Quispe-Huaynasi, F.; Roig, F.; McDonald, Devin; Loaiza-Tacuri, V.; Majewski, Steven R.; Wanderley, Fábio; Cunha, Kátia; Pereira, C. B.; Hasselquist, Sten; Daflon, S.

doi:10.3847/1538-3881/ac90bc

Cited by 6 publications

(4 citation statements)

References 107 publications

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“…In addition to the above searches, several other systematical searches purely based on Gaia DR2 have also reported hundreds of HiVel/HVS candidates (Bromley et al 2018;Hattori et al 2018;Du et al 2019;Marchetti et al 2019;Li et al 2020;Marchetti 2021;Reggiani et al 2022;Quispe-Huaynasi et al 2022;Liao et al 2023). Comparing our sample with those candidates, we find three (including one star, LG-HVS35, which is also included in Li21; see above), three, one, and five candidates in common with Bromley et al (2018), Hattori et al (2018), Du et al (2019) and Li et al (2020), respectively.…”

Section: Comparisons With Other Workmentioning

confidence: 94%

On the Origins of Extreme Velocity Stars as Revealed by Large-scale Galactic Surveys

Qing-Zheng

Huang

Dong

et al. 2023

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We assemble a large sample of 12,784 high-velocity stars with total velocity V GSR ≥ 300 km s−1, selected from RAVE DR5, SDSS DR12, LAMOST DR8, APOGEE DR16, GALAH DR2, and Gaia EDR3. In this sample, 52 are marginally hypervelocity star (HVS) candidates that have V GSR exceeding their local escape velocities within 2σ confidence levels, 40 of which are discovered for the first time. All of the candidates are metal-poor, late-type halo stars, which are significantly different from the previously identified HVSs, which are largely massive early-type stars, discovered by extreme radial velocity. This finding suggests that our newly identified HVS candidates are ejected by different mechanisms from the previous population. To investigate their origins, for 547 extreme velocity stars with V GSR ≥ 0.8V esc, we reconstruct their backward-integrated trajectories in the Galactic potential. According to the orbital analysis, no candidates are found to be definitely ejected from the Galactic-center (GC), while eight metal-poor extreme velocity stars are found to have a closest distance to the GC within 1 kpc. Intriguingly, 15 extreme velocity stars (including 2 HVS candidates) are found to have experienced close encounters with the Sagittarius dSph, suggesting that they originated from this dSph. This hypothesis is supported by an analysis of the [α/Fe]–[Fe/H] diagram. From a preliminary analysis of all of the 547 extreme velocity stars, we propose a general picture–star ejection from Galactic subsystems such as dwarf galaxies and globular clusters can be an important channel to produce extreme velocity stars or even HVSs, particularly the metal-poor late-type halo population.

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Section: Comparisons With Other Workmentioning

confidence: 94%

On the Origins of Extreme Velocity Stars as Revealed by Large-scale Galactic Surveys

Qing-Zheng

Huang

Dong

et al. 2023

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“…According to DR3, Gaia DR3 1591615309672292224 is a long-period variable candidate. It was also found to be a high-velocity star by Quispe-Huaynasi et al (2022). A spectroscopic binary classification is given in DR3 for Gaia DR3 6666207818021916416, which is also included in DR6 of the Radial Velocity Experiment (RAVE; Steinmetz et al 2020) and the Catalina Surveys Southern periodic variable star catalogue (Drake et al 2017).…”

Section: Comparison With Dr3 Radial Velocitiesmentioning

confidence: 99%

Hypervelocity star candidates from Gaia DR2 and DR3 proper motions and parallaxes

Scholz

2024

A&A

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Hypervelocity stars (HVSs) unbound to the Galaxy can be formed with extreme stellar interactions, for example close encounters with supermassive black holes or in massive star clusters, supernova explosions in binary systems, or the stripping of dwarf galaxies. Observational evidence comes from measurements of radial velocities (RVs) of objects crossing the outer Galactic halo and of tangential velocities based on high proper motions (HPMs) and distances of relatively nearby stars. I searched for new nearby HVS candidates and reviewed known objects using their Gaia astrometric measurements. Candidates were selected with significant Gaia parallaxes of $>$0.1\,mas, proper motions of $>$20\,mas/yr, and computed galactocentric tangential velocities $vtan\_g$$>$500\,km/s. The DR2 and DR3 samples of several thousand HVS candidates were studied with respect to their proper motions, sky distribution, number of observations, location in crowded fields, colour-magnitude diagrams, selection effects with magnitude, and RVs in DR3. The 72 most extreme ($vtan\_g$$>$700\,km/s) and nearest (within 4\,kpc) DR3 HVS candidates were investigated with respect to detected close neighbours, flags, and astrometric quality parameters of objects of similar magnitudes in DR3. The quality checks involved HPM objects in a global comparison and all objects in the vicinity of each target. Spurious HPMs in the Galactic centre region led to false HVS interpretations in Gaia DR2 and are still present in DR3, although to a lesser extent. Otherwise there is good agreement between the HPMs of HVS candidates in DR2 and DR3. However, HVS candidates selected from DR2 tend to have larger parallaxes, and hence lower tangential velocities in DR3. Most DR3 RVs are much lower than the tangential velocities, indicating that the DR3 HVS candidates are still affected by underestimated parallaxes. None of the 72 extreme nearby DR3 HVS candidates, including three D$^6$ stars, passed all the quality checks. Their tangential velocities may turn out to be lower, but at least some of them still appear unbound to the Galaxy.

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“…The existence of high-velocity stars (HiVels) implies the presence of extreme dynamics. In the literature, these stars are typically divided into four categories: hypervelocity stars (HVSs), hyper-runaway stars (HRSs), runaway stars (RSs), and high-velocity halo stars (Li et al 2021;Quispe-Huaynasi et al 2022). The first two types of HiVels are unbound stars, with speeds exceeding the escape velocity of the Milky Way (MW).…”

Section: Introductionmentioning

confidence: 99%

The Origin of High-velocity Stars Considering the Impact of the Large Magellanic Cloud

Liao,

Du,

Deng

et al. 2024

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Utilizing astrometric parameters sourced from Gaia Data Release 3 and radial velocities obtained from various spectroscopic surveys, we identify 519 high-velocity stars (HiVels) with a total velocity in the Galactocentric rest frame greater than 70% of their local escape velocity under the Gala MilkyWayPotential. Our analysis reveals that the majority of these HiVels are metal-poor late-type giants, and we show nine HiVels that are unbound candidates to the Galaxy with escape probabilities of 50%. To investigate the origins of these HiVels, we classify them into four categories and consider the impact of the Large Magellanic Cloud (LMC) potential on their backward-integration trajectories. Specifically, we find that one of the HiVels can track back to the Galactic center, and three HiVels may originate from the Sagittarius dwarf spheroidal galaxy (Sgr dSph). Furthermore, some HiVels appear to be ejected from the Galactic disk, while others formed within the Milky Way or have an extragalactic origin. Given that the LMC has a significant impact on the orbits of Sgr dSph, we examine the reported HiVels that originate from the Sgr dSph, with a few of them passing within the half-light radius of the Sgr dSph.

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High-velocity Stars in SDSS/APOGEE DR17

Cited by 6 publications

References 107 publications

On the Origins of Extreme Velocity Stars as Revealed by Large-scale Galactic Surveys

On the Origins of Extreme Velocity Stars as Revealed by Large-scale Galactic Surveys

Hypervelocity star candidates from Gaia DR2 and DR3 proper motions and parallaxes

The Origin of High-velocity Stars Considering the Impact of the Large Magellanic Cloud

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