Search Publications
Dependency of Dynamical Ejections of O Stars on the Masses of Very Young Star Clusters
Kroupa, Pavel; Pflamm-Altenburg, Jan; Oh, Seungkyung
Massive stars can be efficiently ejected from their birth star clusters through encounters with other massive stars. We study how the dynamical ejection fraction of O star systems varies with the masses of very young star clusters, {{M}ecl}, by means of direct N-body calculations. We include diverse initial conditions by varying the hal…
New Near-infrared Period-Luminosity-Metallicity Relations for RR Lyrae Stars and the Outlook for Gaia
Luri, X.; Clementini, G.; Ripepi, V. +6 more
We present results of the analysis of 70 RR Lyrae stars located in the bar of the Large Magellanic Cloud (LMC). Combining the spectroscopically determined metallicity of these stars from the literature with precise periods from the OGLE III catalog and multi-epoch Ks photometry from the VISTA survey of the Magellanic Clouds system, we d…
Action-space Clustering of Tidal Streams to Infer the Galactic Potential
Hogg, David W.; Helmi, Amina; Sanderson, Robyn E.
We present a new method for constraining the Milky Way halo gravitational potential by simultaneously fitting multiple tidal streams. This method requires three-dimensional positions and velocities for all stars to be fit, but does not require identification of any specific stream or determination of stream membership for any star. We exploit the …
Proper Motions and Trajectories for 16 Extreme Runaway and Hypervelocity Stars
Anderson, Jay; Bond, Howard E.; Geller, Margaret J. +3 more
We measure proper motions with the Hubble Space Telescope for 16 extreme radial velocity stars, mostly unbound B stars in the Milky Way halo. Twelve of these stars have proper motions statistically consistent with zero, and thus have radial trajectories statistically consistent with a Galactic center “hypervelocity star” origin. The trajectory of …
Constraints on the Initial-Final Mass Relation from Wide Double White Dwarfs
Anderson, Scott F.; Gianninas, A.; Kilic, Mukremin +3 more
We present observational constraints on the initial-final mass relation (IFMR) using wide double white dwarfs (DWDs). We identify 65 new candidate wide DWDs within the Sloan Digital Sky Survey, bringing the number of candidate wide DWDs to 142. We then engage in a spectroscopic follow-up campaign and collect existing spectra for these objects; usi…
Predicting GAIA's Parallax Distance to the Cygnus OB2 Association with Eclipsing Binaries
Kobulnicky, Henry A.; Lundquist, Michael J.; Vargas Álvarez, Carlos A. +2 more
The Cygnus OB2 Association is one of the nearest and largest collections of massive stars in the Galaxy. Situated at the heart of the “Cygnus X” complex of star-forming regions and molecular clouds, its distance has proven elusive owing to the ambiguous nature of kinematic distances along this ℓ ≃ 80° sightline and the heavy, patchy extinction. In…
Signatures of Kinematic Substructure in the Galactic Stellar Halo
Spergel, David N.; Lisanti, Mariangela; Madau, Piero
Tidal debris from infalling satellites can leave observable structure in the phase-space distribution of the Galactic halo. Such substructure can be manifest in the spatial and/or velocity distributions of the stars in the halo. This paper focuses on a class of substructure that is purely kinematic in nature, with no accompanying spatial features.…