Search Publications
Mass and Mass Scalings of Super-Earths
Wu, Yanqin
The majority of the transiting planets discovered by the Kepler mission (called super-Earths here, includes the so-called “sub-Neptunes”) orbit close to their stars. As such, photoevaporation of their hydrogen envelopes etches sharp features in an otherwise bland space spanned by planet radius and orbital period. This, in turn, can be exploited to…
Analysis of Helium-rich White Dwarfs Polluted by Heavy Elements in the Gaia Era
Bergeron, P.; Dufour, P.; Allard, N. F. +4 more
We present an analysis of 1023 DBZ/DZ(A) and 319 DQ white dwarf stars taken from the Montreal White Dwarf Database. This represents a significant increase over the previous comprehensive studies on these types of objects. We use new trigonometric parallax measurements from the Gaia second data release, together with photometry from the Sloan Digit…
A Temporary Epoch of Stalled Spin-down for Low-mass Stars: Insights from NGC 6811 with Gaia and Kepler
Agüeros, Marcel A.; Curtis, Jason Lee; Douglas, Stephanie T. +1 more
Stellar rotation was proposed as a potential age diagnostic that is precise, simple, and applicable to a broad range of low-mass stars (≤slant 1 {M}⊙ ). Unfortunately, rotation period ({P}{{rot}}) measurements of low-mass members of open clusters have undermined the idea that stars spin down with a common age dependence (i.e.…
Black Hole Mass Scaling Relations for Early-type Galaxies. I. M BH-M *, sph and M BH-M *,gal
Graham, Alister W.; Davis, Benjamin L.; Sahu, Nandini
Analyzing a sample of 84 early-type galaxies (ETGs) with directly measured supermassive black hole masses -- nearly doubling the sample size of such galaxies with multicomponent decompositions -- a symmetric linear regression on the reduced (merger-free) sample of 76 galaxies reveals MBH ∝ M*,sph1.27+/-0.07 with a …
Optical Spectroscopy and Demographics of Redback Millisecond Pulsar Binaries
Strader, Jay; Bahramian, Arash; Cheung, C. C. +12 more
We present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. The properties of these millisecond pulsar binaries with low-mass, hydrogen-rich companions are discussed in the context of the 14 confirmed and 10 candidate field…
A Multimass Velocity Dispersion Model of 47 Tucanae Indicates No Evidence for an Intermediate-mass Black Hole
Anderson, Jay; Caiazzo, Ilaria; Baumgardt, Holger +6 more
In this paper, we analyze stellar proper motions in the core of the globular cluster 47 Tucanae to explore the possibility of an intermediate-mass black hole (IMBH) influence on the stellar dynamics. Our use of short-wavelength photometry affords us an exceedingly clear view of stellar motions into the very center of the crowded core, yielding pro…
A Cooling Anomaly of High-mass White Dwarfs
Cheng, Sihao; Cummings, Jeffrey D.; Ménard, Brice
Recently, the power of Gaia data has revealed an enhancement of high-mass white dwarfs (WDs) on the Hertzsprung-Russell diagram, called the Q branch. This branch is located at the high-mass end of the recently identified crystallization branch. Investigating its properties, we find that the number density and velocity distribution on the Q branch …
X-Ray Properties of SPT-selected Galaxy Clusters at 0.2 < z < 1.5 Observed with XMM-Newton
Miller, Eric D.; Schrabback, Tim; Holzapfel, W. L. +22 more
We present measurements of the X-ray observables of the intracluster medium (ICM), including luminosity L X , ICM mass M ICM, emission-weighted mean temperature T X , and integrated pressure Y X , that are derived from XMM-Newton X-ray observations of a Sunyaev-Zel’dovich effect (SZE) selected sample …
The Analogous Structure of Accretion Flows in Supermassive and Stellar Mass Black Holes: New Insights from Faded Changing-look Quasars
Green, Paul J.; Anderson, Scott F.; Eracleous, Michael +5 more
Despite their factor of ∼108 difference in black hole mass, several lines of evidence suggest possible similarities between black hole accretion flows in active galactic nuclei (AGN) and Galactic X-ray binaries. However, it is still unclear whether the geometry of the disk-corona system in X-ray binaries directly scales up to AGN and wh…
Resolving the Metallicity Distribution of the Stellar Halo with the H3 Survey
Conroy, Charlie; Johnson, Benjamin D.; Caldwell, Nelson +4 more
The Galactic stellar halo is predicted to have formed at least partially from the tidal disruption of accreted dwarf galaxies. This assembly history should be detectable in the orbital and chemical properties of stars. The H3 Survey is obtaining spectra for 200,000 stars and, when combined with Gaia data, is providing detailed orbital and chemical…