Search Publications
Blue Straggler Stars beyond the Milky Way. II. A Binary Origin for Blue Straggler Stars in Magellanic Cloud Clusters
Deng, Licai; de Grijs, Richard; Li, Chengyuan +1 more
We have analyzed populations of blue straggler stars (BSSs) in 24 Magellanic Cloud (MC) star clusters using multi-passband Hubble Space Telescope images. We compiled a homogeneous BSS database, containing both traditional and evolved BSSs. We uncovered a sublinear correlation between the number of BSSs in the cluster cores and the clusters’ core m…
Chemical Evolution of N2H+ in Six Massive Star-forming Regions
Wang, Jun-Jie; Xu, Jin-Long; Liu, Xiao-Lan +1 more
To investigate how the abundance of N2H+ varies as massive clumps evolve, here we present a multiwavelength study toward six molecular clouds. All of these clouds contain several massive clumps in different evolutionary stages of star formation. Using archival data of the Herschel infrared Galactic Plane Survey (Hi-GAL), we m…
The Year-long Flux Variations in Boyajian's Star Are Asymmetric or Aperiodic
Hippke, Michael; Angerhausen, Daniel
We combine and calibrate publicly available data for Boyajian’s star, including photometry from ASAS (SN, V, I), Kepler, Gaia, SuperWASP, and citizen scientist observations (AAVSO, HAO, and Burke-Gaffney). Precise (mmag) photometry covers the years 2006-2017. We show that the year-long flux variations with an amplitude of ≈4% cannot be explained w…
X-Ray Study of Variable Gamma-Ray Pulsar PSR J2021+4026
Takata, J.; Zhao, J.; Lin, L. C. C. +2 more
PSR J2021+4026 showed a sudden decrease in the gamma-ray emission at the glitch that occurred around 2011 October 16, and a relaxation of the flux to the pre-glitch state at around 2014 December. We report X-ray analysis results of the data observed by XMM-Newton on 2015 December 20 in the post-relaxation state. To examine any change in the X-ray …
Cracking the Conundrum of F-supergiant Coronae
Ayres, Thomas R.
Chandra X-ray and HST far-ultraviolet (FUV) observations of three early-F supergiants have shed new light on a previous puzzle involving a prominent member of the class: α Persei (HD 20902: F5 Ib). The warm supergiant is a moderately strong, hard coronal (T∼ {10}7 K) X-ray source, but has 10 times weaker “subcoronal” Si IV 1393 Å (T∼ 8×…
Dense Molecular Filaments Feeding a Starburst: ALMA Maps of CO(3-2) in Henize 2-10
Turner, Jean L.; Beck, Sara C.; Consiglio, S. Michelle
We present Atacama Large Millimeter/Submillimeter Array CO(3-2) observations at 0.″3 resolution of He 2-10, a starburst dwarf galaxy and possible high-z galaxy analog. The warm dense gas traced by CO(3-2) is found in clumpy filaments that are kinematically and spatially distinct. The filaments have no preferred orientation or direction; this may i…
The Halo Masses of Galaxies to z ∼ 3: A Hybrid Observational and Theoretical Approach
Conselice, Christopher J.; Hartley, William; Twite, Jonathan W. +1 more
We use a hybrid observational/theoretical approach to study the relation between galaxy kinematics and the derived stellar and halo masses of galaxies up to z = 3 as a function of stellar mass, redshift, and morphology. Our observational sample consists of a concatenation of 1125 galaxies with kinematic measurements at 0.4 < z < 3 from long-…
A Transitional Disk around an Intermediate-mass Star in the Sparse Population of the Orion OB1 Association
Briceño, Cesar; Calvet, Nuria; Hernández, Jesús +8 more
We present a detailed study of the disk around the intermediate-mass star SO 411, aiming to explain the spectral energy distribution of this star. We show that this is a transitional disk truncated at ∼11 au, with ∼0.03 lunar masses of optically thin dust inside the cavity. Gas also flows through the cavity, since we find that the disk is still ac…
Delayed Stellar Mass Assembly in the Low Surface Brightness Dwarf Galaxy KDG 215
McQuinn, Kristen B. W.; Cannon, John M.; Dolphin, Andrew E. +17 more
We present H I spectral line and optical broadband images of the nearby low surface brightness dwarf galaxy KDG 215. The H I images, acquired with the Karl G. Jansky Very Large Array, reveal a dispersion-dominated interstellar medium with only weak signatures of coherent rotation. The H I gas reaches a peak mass surface density of 6 M ⊙…
2MASS J11151597+1937266: A Young, Dusty, Isolated, Planetary-mass Object with a Potential Wide Stellar Companion
Burgasser, Adam J.; Gagné, Jonathan; Bardalez Gagliuffi, Daniella C. +4 more
We present 2MASS J11151597+1937266, a recently identified low-surface-gravity L dwarf, classified as an L2γ based on Sloan Digital Sky Survey optical spectroscopy. We confirm this spectral type with near-infrared spectroscopy, which provides further evidence that 2MASS J11151597+1937266 is a low-surface-gravity L dwarf. This object also shows sign…