Search Publications
Boyajian's Star B: The Co-moving Companion to KIC 8462852 A
Huber, Daniel; Dupuy, Trent J.; Kraus, Adam L. +2 more
The light curve of KIC 8462852, aka Boyajian's Star, undergoes deep dips the origin of which remains unclear. A faint star ≈2″ to the east was discovered in Keck/NIRC2 imaging in Boyajian et al., but its status as a binary, and possible contribution to the observed variability, was unclear. Here, we use three epochs of Keck/NIRC2 imaging, spanning…
Milky Way-like Gas Excitation in an Ultrabright Submillimeter Galaxy at z = 1.6
Rebolo, R.; Dannerbauer, H.; Ziegler, B. +3 more
Based on observations with the IRAM 30 m and Yebes 40 m telescopes, we report evidence of the detection of Milky Way-like, low-excitation molecular gas, up to the transition CO(J = 5-4), in a distant, dusty star-forming galaxy at z CO = 1.60454. WISE J122651.0+214958.8 (alias SDSS J1226, the Cosmic Seahorse), is strongly lensed by a for…
Combined Analysis of X-Ray Spectra of NGC 3227
Newman, J.; Liebmann, A. C.; Haba, Y. +2 more
The 1.5 Seyfert galaxy NGC 3227 has been observed by several X-ray missions. We carried out a combined analysis of the data obtained by more recent major observations of this source—two observations performed by XMM-Newton in 2000 and 2006 and six observations performed by Suzaku in 2008. A unified model, which is consistent with all eight of the …
Chemodynamically Characterizing the Jhelum Stellar Stream with APOGEE-2
Cunha, Katia; Smith, Verne V.; Majewski, Steven R. +15 more
We present the kinematic and chemical profiles of red giant stars observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE)-2 survey in the direction of the Jhelum stellar stream, a Milky Way substructure located in the inner halo of the Milky Way at a distance from the Sun of ≈13 kpc. From the six APOGEE-2 Jhelum pointings, …
Brightness Fluctuation Spectra of Sun-like Stars. I. The Mid-frequency Continuum
Metcalfe, Travis S.; García, Rafael A.; Mathur, Savita +2 more
We analyze space-based time-series photometry of Sun-like stars, mostly in the Pleiades, but also field stars and the Sun itself. We focus on timescales between roughly 1 hr and 1 day. In the corresponding frequency band these stars display brightness fluctuations with a decreasing power-law continuous spectrum. K2 and Kepler observations show tha…
Pre-explosion Properties of Helium Star Donors to Thermonuclear Supernovae
Schwab, Josiah; Götberg, Ylva; Wong, Tin Long Sunny
Helium star-carbon-oxygen white dwarf (CO WD) binaries are potential single-degenerate progenitor systems of thermonuclear supernovae. Revisiting a set of binary evolution calculations using the stellar evolution code MESA, we refine our previous predictions about which systems can lead to a thermonuclear supernova and then characterize the proper…
Multiple Stellar Populations at Less-evolved Stages-II: No Evidence of Significant Helium Spread among NGC 1846 Dwarfs
Li, Chengyuan
The detection of star-to-star chemical variations in star clusters older than 2 Gyr has changed the traditional view of star clusters as canonical examples of "simple stellar populations" into the so-called "multiple stellar populations" (MPs). Although the significance of MPs seems to correlate with cluster total mass, it seems that the presence …
Terahertz Water Masers. II. Further SOFIA/GREAT Detections Toward Circumstellar Outflows, and a Multitransition Analysis
Wyrowski, Friedrich; Menten, Karl M.; Wiesemeyer, Helmut +8 more
Following up on our discovery of terahertz water masers, reported in 2017, we report two further detections of water maser emission at frequencies above 1 THz. Using the GREAT instrument on SOFIA, we have detected emission in the 1.296411 THz 827 - 734 transition of water toward two additional oxygen-rich evolved stars, omicr…
Detailed Abundances of Planet-hosting Open Clusters. The Praesepe (Beehive) Cluster
Stassun, Keivan G.; Schuler, Simon C.; Vejar, George
It is not yet fully understood how planet formation affects the properties of host stars, in or out of a cluster; however, abundance trends can help us understand this process. We present a detailed chemical abundance analysis of six stars in Praesepe, a planet-hosting open cluster. Pr0201 is known to host a close-in (period of 4.4 days) giant pla…
Molecular Gas in a Gravitationally Lensed Galaxy Group at z = 2.9
Richard, Johan; Brammer, Gabriel; Whitaker, Katherine E. +5 more
Most molecular gas studies of z > 2.5 galaxies are of intrinsically bright objects, despite the galaxy population being primarily normal galaxies with less extreme star formation rates. Observations of normal galaxies at high redshift provide a more representative view of galaxy evolution and star formation, but such observations are challengin…