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Related papers: A hypervelocity star with a Magellanic origin

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The first three hyper-velocity stars (HVS) unbound to the Galaxy were serendipitously discovered in 2005. The only suggested origin of hyper-velocity stars is the Galactic Centre as it hosts a super-massive black hole capable of…

We describe our completed spectroscopic survey for unbound hypervelocity stars (HVSs) ejected from the Milky Way. Three new discoveries bring the total number of unbound HVSs to 21. We place new constraints on the nature of HVSs and on…

Solar and Stellar Astrophysics · Physics 2015-06-18 Warren R. Brown , Margaret J. Geller , Scott J. Kenyon

We obtain Keck HIRES spectroscopy of HVS5, one of the fastest unbound stars in the Milky Way halo. We show that HVS5 is a 3.62 +- 0.11 Msun main sequence B star at a distance of 50 +- 5 kpc. The difference between its age and its flight…

Astrophysics of Galaxies · Physics 2015-06-05 Warren R. Brown , Judith G. Cohen , Margaret J. Geller , Scott J. Kenyon

High-velocity clouds (HVCs) are multi-phase gas structures whose velocities (|v_LSR|>100 km/s) are too high to be explained by Galactic disk rotation. While large HVCs are well characterized, compact and small HVCs (with HI angular sizes of…

Recent Gaia observations suggest that some hypervelocity stars (HVSs) might originate from outside the Galaxy. We ask if these HVSs could come from as far as Andromeda. Therefore, we simulate HVSs originating in Andromeda with initial…

Astrophysics of Galaxies · Physics 2024-04-16 Lukas Gülzow , Malcolm Fairbairn , Dominik J. Schwarz

The discovery of hypervelocity stars (HVS) leaving our galaxy with speeds of nearly $10^{3}$ km s$^{-1}$ has provided strong evidence towards the existence of a massive compact object at the galaxy's center. HVS ejected via the disruption…

Astrophysics of Galaxies · Physics 2015-06-18 James Guillochon , Abraham Loeb

From an analysis of the sky and velocity distributions of the high-velocity clouds (HVCs) we show that the majority of the HVCs has a common origin. We conclude that the HVCs surround the Galaxy, forming a metacloud of 300 kpc in size and…

Astrophysics · Physics 2009-11-11 Carlos A. Olano

We consider how the gravity of the Galactic disk and the Large Magellanic Cloud (LMC) modifies the radial motions of hypervelocity stars (HVSs) ejected from the Galactic Center. For typical HVSs ejected towards low (high) Galactic…

Solar and Stellar Astrophysics · Physics 2018-09-19 Scott J Kenyon , Benjamin C. Bromley , Warren R. Brown , Margaret J. Geller

Hypervelocity stars (HVSs) discovered in the Milky Way (MW) halo are thought to be ejected from near the massive black hole (MBH) at the galactic centre. In this paper we investigate the spatial and velocity distributions of the HVSs which…

Astrophysics · Physics 2009-11-13 Blake D. Sherwin , Abraham Loeb , Ryan M. O'Leary

The origin of high velocity stars observed in the halo of our Galaxy is still unclear. In this work we test the hypothesis, raised by results of recent high precision $N$-body simulations, of strong acceleration of stars belonging to a…

Astrophysics of Galaxies · Physics 2015-07-03 Roberto Capuzzo-Dolcetta , Giacomo Fragione

The hypervelocity star (HVS) survey conducted at the Multiple Mirror Telescope (MMT) identified 42 B-type stars in the Galactic halo whose radial velocity in the Galactic rest-frame exceeds $+275\,$km$\,$s${}^{-1}$. In order to unravel the…

Solar and Stellar Astrophysics · Physics 2020-05-13 S. Kreuzer , A. Irrgang , U. Heber

Hypervelocity stars are intriguing rare objects traveling at speeds large enough to be unbound from the Milky Way. Several mechanisms have been proposed for producing them, including the interaction of the Galaxy's super-massive black hole…

Astrophysics of Galaxies · Physics 2018-07-04 Douglas Boubert , James Guillochon , Keith Hawkins , Idan Ginsburg , N. Wyn Evans , Jay Strader

Hypervelocity stars (HVSs) ejected from the Galactic Center (GC) at speeds faster than the Galactic escape velocity are useful tools to provide insight into the Milky Way's dark matter halo. However, most characterizations of HVS orbits…

Astrophysics of Galaxies · Physics 2025-03-24 Isabella Armstrong , Fraser A. Evans , Jo Bovy

High-velocity particles ( $v>v_\mathrm{esc}$) in the Milky Way are rare but nonetheless important to characterize due to their impact on dark matter (DM) direct detection experiments. We select halos similar in mass to the Milky Way in a…

Astrophysics of Galaxies · Physics 2025-02-26 Aidan DeBrae , Peter Behroozi , Nicolas Garavito-Camargo

We use new Gaia measurements to explore the origin of the highest velocity stars in the Hypervelocity Star Survey. The measurements reveal a clear pattern in the B-type stars. Halo stars dominate the sample at speeds about 100 km/s below…

Solar and Stellar Astrophysics · Physics 2018-10-17 Warren R. Brown , Mario G. Lattanzi , Scott J. Kenyon , Margaret J. Geller

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…

Solar and Stellar Astrophysics · Physics 2018-07-18 Andreas Irrgang , Simon Kreuzer , Ulrich Heber , Warren Brown

Hypervelocity stars are unique objects moving through the Milky Way at speeds exceeding the local escape velocity, providing valuable insights into the Galactic gravitational potential and the properties of its central supermassive black…

We analyze Keck ESI spectroscopy of HVS17, a B-type star traveling with a Galactic rest frame radial velocity of +445 km/s in the outer halo of the Milky Way. HVS17 has the projected rotation of a main sequence B star and is chemically…

Solar and Stellar Astrophysics · Physics 2015-06-16 Warren R. Brown , Judith G. Cohen , Margaret J. Geller , Scott J. Kenyon

Hypervelocity stars (HVS) traverse the Galaxy from the central black hole to the outer halo. We show that the Galactic potential within 200 pc acts as a high pass filter preventing low velocity HVS from reaching the halo. To trace the…

Astrophysics · Physics 2009-11-13 S. J. Kenyon , B. C. Bromley , M. J. Geller , W. R. Brown

Stars within 0.1 pc of the supermassive black hole Sgr A* at the Galactic centre are expected to encounter a cluster of stellar-mass black holes (BHs) that have segregated to that region. Some of these stars will scatter off an orbiting BH…

Astrophysics · Physics 2008-07-15 Ryan M. O'Leary , Abraham Loeb