Search Publications
White Dwarf Subsystems in Core-Collapsed Globular Clusters
Rui, Nicholas Z.; Rodriguez, Carl L.; Chatterjee, Sourav +5 more
Numerical and observational evidence suggests that massive white dwarfs dominate the innermost regions of core-collapsed globular clusters by both number and total mass. Using NGC 6397 as a test case, we constrain the features of white dwarf populations in core-collapsed clusters, both at present day and throughout their lifetimes. The dynamics of…
Anisotropy of Solar Wind Turbulence in the Inner Heliosphere at Kinetic Scales: PSP Observations
Chen, Christopher H. K.; He, Jiansen; Bale, Stuart D. +5 more
The anisotropy of solar wind turbulence is a critical issue in understanding the physics of energy transfer between scales and energy conversion between fields and particles in the heliosphere. Using the measurement of Parker Solar Probe (PSP), we present an observation of the anisotropy at kinetic scales in the slow, Alfvénic, solar wind in the i…
The R-Process Alliance: Chemodynamically Tagged Groups of Halo r-process-enhanced Stars Reveal a Shared Chemical-evolution History
Beers, Timothy C.; Holmbeck, Erika M.; Hansen, Terese T. +11 more
We derive dynamical parameters for a large sample of 446 r-process-enhanced (RPE) metal-poor stars in the halo and disk systems of the Milky Way, based on data releases from the R-Process Alliance, supplemented by additional literature samples. This sample represents more than a 10-fold increase in size relative to that previously considered by Ro…
Discovery of Beryllium in White Dwarfs Polluted by Planetesimal Accretion
Weinberger, Alycia J.; Zuckerman, B.; Blouin, Simon +5 more
The element beryllium is detected for the first time in white dwarf stars. This discovery in the spectra of two helium-atmosphere white dwarfs was made possible only because of the remarkable overabundance of Be relative to all other elements, heavier than He, observed in these stars. The measured Be abundances, relative to chondritic, are by far …
The Strength and Structure of the Magnetic Field in the Galactic Outflow of Messier 82
Lopez-Rodriguez, Enrique; Guerra, Jordan A.; Asgari-Targhi, Mahboubeh +1 more
Galactic outflows driven by starbursts can modify the galactic magnetic fields and drive them away from the galactic planes. Here, we quantify how these fields may magnetize the intergalactic medium (IGM). We estimate the strength and structure of the fields in the starburst galaxy M82 using thermal polarized emission observations from the Stratos…
Constraints on the Assembly History of the Milky Way's Smooth, Diffuse Stellar Halo from the Metallicity-dependent, Radially Dominated Velocity Anisotropy Profiles Probed with K Giants and BHB Stars Using LAMOST, SDSS/SEGUE, and Gaia
Bird, Sarah A.; Zhao, Gang; Tian, Hai-Jun +5 more
We analyze the anisotropy profile of the Milky Way's smooth, diffuse stellar halo using the Sloan Digital Sky Survey (SDSS) SEGUE blue horizontal branch stars and the SDSS/SEGUE and LAMOST K giants. These intrinsically luminous stars allow us to probe the halo to approximately 100 kpc from the Galactic center. Line-of-sight velocities, distances, …
The Single-cloud Star Formation Relation
Henning, Thomas; Myers, Philip C.; Gutermuth, Robert A. +10 more
One of the most important and well-established empirical results in astronomy is the Kennicutt-Schmidt relation between the density of interstellar gas and the rate at which that gas forms stars. A tight correlation between these quantities has long been measured at galactic scales. More recently, using surveys of YSOs, a KS relationship has been …
The Mega-MUSCLES Spectral Energy Distribution of TRAPPIST-1
Loyd, R. O. Parke; Redfield, Seth; Roberge, Aki +19 more
We present a 5 Å-100 µm spectral energy distribution (SED) of the ultracool dwarf star TRAPPIST-1, obtained as part of the Mega-MUSCLES Treasury Survey. The SED combines ultraviolet and blue-optical spectroscopy obtained with the Hubble Space Telescope, X-ray spectroscopy obtained with XMM-Newton, and models of the stellar photosphere, chrom…
Two Contact Binaries with Mass Ratios Close to the Minimum Mass Ratio
Li, Kai; Xia, Qi-Qi; Chen, Xu +5 more
The cutoff mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 (hereafter J132829) are both less than 0.1 (q ~ 0.055 for J08…
Milky Way Tomography with the SkyMapper Southern Survey. II. Photometric Recalibration of SMSS DR2
Huang, Yang; Ting, Yuan-Sen; Beers, Timothy C. +13 more
We apply the spectroscopy-based stellar-color regression (SCR) method to perform an accurate photometric recalibration of the second data release from the SkyMapper Southern Survey (SMSS DR2). From comparison with a sample of over 200,000 dwarf stars with stellar atmospheric parameters taken from GALAH+ DR3 and with accurate, homogeneous photometr…