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The Disk Substructures at High Angular Resolution Project (DSHARP). X. Multiple Rings, a Misaligned Inner Disk, and a Bright Arc in the Disk around the T Tauri star HD 143006
Wilner, David J.; Andrews, Sean M.; Guzmán, Viviana V. +14 more
We present a detailed analysis of new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the disk around the T-Tauri star HD 143006, which at 46 mas (7.6 au) resolution reveals new substructures in the 1.25 mm continuum emission. The disk resolves into a series of concentric rings and gaps, together with a bright arc exterior to t…
Distances and Kinematics of Gould Belt Star-forming Regions with Gaia DR2 Results
Rodríguez, Luis F.; Loinard, Laurent; Ortiz-León, Gisela N. +2 more
We present an analysis of the astrometric results from the Gaia second data release (DR2) for young stellar objects (YSOs) in star-forming regions related to the Gould Belt (GB). These regions are Barnard 59, Lupus 1 to 4, Chamaeleon I and II, ɛ Chamaeleontis, the Cepheus flare, IC 5146, and Corona Australis. The mean distance to the YSOs in each …
SMASHing the LMC: A Tidally Induced Warp in the Outer LMC and a Large-scale Reddening Map
Bell, Eric F.; Monachesi, Antonela; Choi, Yumi +18 more
We present a study of the three-dimensional (3D) structure of the Large Magellanic Cloud (LMC) using ∼2.2 million red clump (RC) stars selected from the Survey of the MAgellanic Stellar History. To correct for line-of-sight dust extinction, the intrinsic RC color and magnitude and their radial dependence are carefully measured by using internal ne…
Retired A Stars Revisited: An Updated Giant Planet Occurrence Rate as a Function of Stellar Metallicity and Mass
Montet, Benjamin T.; Johnson, John Asher; Ghezzi, Luan
Exoplanet surveys of evolved stars have provided increasing evidence that the formation of giant planets depends not only on stellar metallicity ([Fe/H]) but also on the mass ({M}\star ). However, measuring accurate masses for subgiants and giants is far more challenging than it is for their main-sequence counterparts, which has led to …
The Dragonfly Nearby Galaxies Survey. V. HST/ACS Observations of 23 Low Surface Brightness Objects in the Fields of NGC 1052, NGC 1084, M96, and NGC 4258
Mowla, Lamiya; van Dokkum, Pieter; Romanowsky, Aaron J. +8 more
We present Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging of 23 very low surface brightness (µ e,V ∼ 25-27.5) galaxies detected in the fields of four nearby galaxy groups. These objects were selected from deep optical imaging obtained with the Dragonfly Telephoto Array. Seven are newly identified, while most of…
The Circumgalactic Medium of eBOSS Emission Line Galaxies: Signatures of Galactic Outflows in Gas Distribution and Kinematics
Lan, Ting-Wen; Mo, Houjun
We study the distribution and kinematics of the cool circumgalactic medium (CGM) of emission line galaxies (ELGs) traced by metal absorption lines. Using about 200,000 ELGs from SDSS-IV eBOSS and half a million background quasars from SDSS, we measure the median absorption strength of Mg II and Fe II lines in quasar spectra for impact parameters r…
Detection of Additional Be+sdO Systems from IUE Spectroscopy
Gies, Douglas R.; Wang, Luqian; Peters, Geraldine J.
There is growing evidence that some Be stars were spun up through mass transfer in a close binary system, leaving the former mass donor star as a hot, stripped-down object. There are five known cases of Be stars with hot subdwarf (sdO) companions that were discovered through International Ultraviolet Explorer (IUE) spectroscopy. Here we expand the…
Extended Main-sequence Turnoff as a Common Feature of Milky Way Open Clusters
Di Criscienzo, M.; Milone, A. P.; Cordoni, G. +5 more
We present photometric analysis of 12 Galactic open clusters and show that the same multiple-population phenomenon observed in Magellanic Clouds (MCs) is present in nearby open clusters. Nearly all the clusters younger than ∼2.5 Gyr of both MCs exhibit extended main-sequence turnoffs (eMSTOs) and all the cluster younger than ∼700 Myr show broadene…
A New Generation of Cool White Dwarf Atmosphere Models. I. Theoretical Framework and Applications to DZ Stars
Dufour, P.; Allard, N. F.; Blouin, S.
The photospheres of the coolest helium-atmosphere white dwarfs are characterized by fluidlike densities. Under those conditions, standard approximations used in model atmosphere codes are no longer appropriate. Unfortunately, the majority of cool He-rich white dwarfs show no spectral features, giving us no opportunities to put more elaborate model…
Gamma-Ray Burst Jet Breaks Revisited
Zhang, Bing; Lin, Da-Bin; Li, Jing +4 more
Gamma-ray Burst (GRB) collimation has been inferred with the observations of achromatic steepening in GRB light curves, known as jet breaks. Identifying a jet break from a GRB afterglow light curve allows a measurement of the jet opening angle and true energetics of GRBs. In this paper, we re-investigate this problem using a large sample of GRBs t…