390 citations · 929 across the 31 of their papers we have counts for
31 papers
A Quality Framework for Testing Gravity with Wide Binaries: No Evidence for MOND
Stephen A. Cookson, Indranil Banik, Kareem El-Badry +4
Wide binaries (WBs) offer a unique opportunity to test gravity in the low-acceleration regime, where modifications such as Milgromian dynamics (MOND) predict measurable deviations…
Discovery of Galactic center ejected star in DESI DR1
Manuel Cavieres, Sergey E. Koposov, Elena Maria Rossi +2
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…
The position and resolvability of blended point sources
Zephyr Penoyre
In this work we derive analytic expressions and numerical recipes for finding the effective observed position of sources close enough on sky that their Point Spread Functions (PSF)…
Astrometric view of companions in the inner dust cavities of protoplanetary disks
Miguel Vioque, Richard A. Booth, Enrico Ragusa +16
Protoplanetary disks with inner dust cavities (often referred to as "transition disks") are potential signposts of planet formation. We use Gaia astrometry to search for planetary…
Nominal thresholds for good astrometric fits, and prospects for binary detectability, for the full extended Gaia mission
F. Guerriero, Z. Penoyre, A. G. A. Brown
The full extended Gaia mission spans slightly over 10 years, whilst the current data releases represent only a fraction of it, 34 months in Gaia's third data release (DR3). The lon…
Searching for stars ejected from the Galactic Centre in DESI
Sill Verberne, Sergey E. Koposov, Elena Maria Rossi +1
Dynamical interactions between stars and the super massive black hole Sgr A* at the Galactic Centre (GC) may eject stars into the Galactic halo. While recent fast ejections by Sgr…
Dynamics of recaptures, ejections and mergers of stellar mass binaries over multiple encounters with SgrA*
Biancamaria Sersante, Zephyr Penoyre, Elena Maria Rossi
A common origin for a host of stellar phenomena in galactic centres is the tidal encounter between stellar binaries and a massive black hole (MBH), known as the ``Hills mechanism''…
Disruptions of stars and binary systems on chaotic orbits in an axisymmetric Milky Way center
Zephyr Penoyre, Elena Maria Rossi, Nicholas C. Stone
Non-spherical potentials allow a wide range of trajectories, both regular and chaotic, whose periapse distances can vary orbit to orbit. In particular chaotic trajectories can brin…
Double progenitor origin of the S-star cluster
Sill Verberne, Elena Maria Rossi, Sergey E. Koposov +3
The origin of the cluster of S-stars located in the Galactic Centre is tied to the supermassive black hole Sagittarius A*, but exactly how is still debated. In this paper, we inves…
Improved constraints on Galactic Centre ejection of hypervelocity stars based on novel search method
Sill Verberne, Elena Maria Rossi, Sergey E. Koposov +6
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 an…
Carbon enrichment in APOGEE disk stars as evidence of mass transfer in binaries
Steve Foster, Ricardo P. Schiavon, Denise B. de Castro +10
Carbon abundances in first-ascent giant stars are usually lower than those of their main-sequence counterparts. At moderate metallicities, stellar evolution of single stars cannot…
Gaia DR3 detectability of unresolved binary systems
Alfred Castro-Ginard, Zephyr Penoyre, Andrew R. Casey +10
Gaia can not individually resolve very close binary systems, however, the collected data can still be used to identify them. A powerful indicator of stellar multiplicity is the sou…
WD0141-675: A case study on how to follow-up astrometric planet candidates around white dwarfs
Laura K. Rogers, John Debes, Richard J. Anslow +22
This work combines spectroscopic and photometric data of the polluted white dwarf WD0141-675 which has a now retracted astrometric super-Jupiter candidate and investigates the most…
Radial velocities from Gaia BP/RP spectra
Sill Verberne, Sergey E. Koposov, Elena M. Rossi +3
The Gaia mission has provided us full astrometric solutions for over 1.5B sources. However, only the brightest 34M of those have radial velocity measurements. As a proof of concept…
Stellar-mass black holes in the Hyades star cluster?
Stefano Torniamenti, Mark Gieles, Zephyr Penoyre +3
Astrophysical models of binary-black hole mergers in the Universe require a significant fraction of stellar-mass black holes (BHs) to receive negligible natal kicks to explain the…
High resolution ALMA and HST imaging of CrB: a broad debris disc around a post-main sequence star with low-mass companions
J. B. Lovell, M. C. Wyatt, P. Kalas +6
CrB is a Gyr old K1 sub-giant star, with an eccentric exo-Jupiter at au and a debris disc at tens of au. We present ALMA Band 6 (mm) and HST sca…
Is there a nearby microlensing stellar remnant hiding in Gaia DR3 astrometry?
Maja Jabłońska, Łukasz Wyrzykowski, Krzysztof A. Rybicki +3
Massive galactic lenses with large Einstein Radii should cause a measurable astrometric microlensing effect, i.e. the light centroid shift due to the motion of the two images. Such…
Binary parameters from astrometric and spectroscopic errors--candidate hierarchical triples and massive dark companions in Gaia DR3
Shion Andrew, Zephyr Penoyre, Vasily Belokurov +2
We show how astrometric and spectroscopic errors introduced by an unresolved binary system can be combined to give estimates of the binary period and mass ratio. This can be perfor…
Astrometric identification of nearby binary stars II: Astrometric binaries in the Gaia Catalogue of Nearby Stars
Zephyr Penoyre, Vasily Belokurov, N. Wyn Evans
We examine the capacity to identify binary systems from astrometric deviations alone. We apply our analysis to the Gaia eDR3 and DR2 data, specifically the Gaia Catalogue of Nearby…
Astrometric Identification of Nearby Binary Stars I: Predicted Astrometric Signals
Zephyr Penoyre, Vasily Belokurov, N. Wyn Evans
We examine the capacity to identify binary systems from astrometric errors and deviations alone. Until the release of the fourth Gaia data release we lack the full astrometric time…
VVV-WIT-08: the giant star that blinked
Leigh C. Smith, Sergey E. Koposov, Philip W. Lucas +11
We report the serendipitous discovery of a late-type giant star that exhibited a smooth, eclipse-like drop in flux to a depth of 97 per cent. Minimum flux occurred in April 2012 an…
Unresolved stellar companions with Gaia DR2 astrometry
Vasily Belokurov, Zephyr Penoyre, Semyeong Oh +9
For stars with unresolved companions, motions of the centre of light and that of mass decouple, causing a single-source astrometric model to perform poorly. We show that such stars…
Binary deviations from single object astrometry
Zephyr Penoyre, Vasily Belokurov, N. Wyn Evans +2
Most binaries are undetected. Astrometric reductions of a system using the assumption that the object moves like a single point mass can be biased by unresolved binary stars. The d…
The Spaceline: a practical space elevator alternative achievable with current technology
Zephyr Penoyre, Emily Sandford
Perhaps the biggest hurdle to mankind's expansion throughout the Solar System is the prohibitive cost of escaping Earth's gravitational pull. In its many forms, the space-elevator…