Search Publications
Combining Astrometry and Elemental Abundances: The Case of the Candidate Pre-Gaia Halo Moving Groups G03-37, G18-39, and G21-22
Agüeros, Marcel A.; Schuler, Simon C.; Andrews, Jeff J. +3 more
While most moving groups are young and nearby, a small number have been identified in the Galactic halo. Understanding the origin and evolution of these groups is an important piece of reconstructing the formation history of the halo. Here we report on our analysis of three putative halo moving groups: G03-37, G18-39, and G21-22. Based on Gaia EDR…
Stellar and Accretion Disk Parameters of the Close Binary HD 50526
Mennickent, R. E.; Zharikov, S.; Djurašević, G. +5 more
We present a photometric and spectroscopic study of HD 50526, an ellipsoidal binary member of the group Double Periodic Variable stars. Performing data mining in photometric surveys and conducting new spectroscopic observations with several spectrographs during 2008-2015, we obtained orbital and stellar parameters of the system. The radial velocit…
High-resolution CARMA Observation of Molecular Gas in the North America and Pelican Nebulae
Mairs, Steve; Nakamura, Fumitaka; Klessen, Ralf S. +15 more
In this paper, we present the first results from a CARMA high-resolution 12CO(1-0), 13CO(1-0), and C18O(1-0) molecular line survey of the North America and Pelican (NAP) Nebulae. CARMA observations have been combined with single-dish data from the Purple Mountain 13.7 m telescope, to add short spacings and to produ…
K2, Spitzer, and TESS Transits of Four Sub-Neptune Exoplanets
Deming, Drake; Crossfield, Ian; Harada, Caleb K. +5 more
We present new Spitzer transit observations of four K2 transiting sub-Neptunes: K2-36 c, K2-79b, K2-167b, and K2-212b. We derive updated orbital ephemerides and radii for these planets based on a joint analysis of the Spitzer, TESS, and K2 photometry. We use the EVEREST pipeline to provide improved K2 photometry, by detrending instrumental noise a…
Census of Variable Stars toward Serpens Main
Chen, Zhiwei; Li, Yao; Haas, Martin +7 more
We monitored a 3 deg2 area toward Serpens Main in the Pan-STARRS1 r, i, and z bands from 2016 April to September. Light curves of more than 11,000 stars in each band were obtained, and 143 variables have been identified. Among those, 119 variables are new discoveries, while 24 variables were previously known. We present variability clas…
Searching for Low-mass Population III Stars Disguised as White Dwarfs
Schlaufman, Kevin C.; Chandra, Vedant
It is uncertain whether or not low-mass Population III stars ever existed. While limits on the number density of Population III stars with M* ≈ 0.8 M⊙ have been derived, using Sloan Digital Sky Survey (SDSS) data, little is known about the occurrence of Population III stars at lower masses. In the absence of reliable parallax…
Reinvestigation of the Multiepoch Direct Detections of HD 88133 b and Upsilon Andromedae b
Barman, Travis S.; Benneke, Björn; Bender, Chad F. +5 more
We reanalyze the multiepoch direct detections of HD 88133 b and ups And b that were published in Piskorz et al. (2016) and Piskorz et al. (2017), respectively. Using simulations to attempt to reproduce the detections, we find that with the six and seven L-band Keck/NIRSPEC epochs analyzed in the original works, the planets would not have been dete…
Analysis of Previously Classified White Dwarf-Main-sequence Binaries Using Data from the APOGEE Survey
Cunha, Katia; Majewski, Steven R.; Stassun, Keivan G. +12 more
We present analyses of near-infrared spectroscopic data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey for 45 previously confirmed or candidate white dwarf-main-sequence (WDMS) binaries identified by the optical Sloan Digital Sky Survey (SDSS) and LAMOST surveys. Among these 45 systems, we classify three as having …
Light Element Abundances and Multiple Populations in M53
Vesperini, Enrico; Gerber, Jeffrey M.; Friel, Eileen D.
We present results from a study of 94 red giant stars in the globular cluster M53. We use low-resolution spectra to measure the strength of CN and CH features at ∼3800 and 4300 Å, respectively. The strengths of these features are used to classify stars into a CN-enhanced and CN-normal population and to measure C and N abundances in all 94 stars. W…
SOFIA upGREAT/FIFI-LS Emission-line Observations of Betelgeuse during the Great Dimming of 2019/2020
Harper, Graham M.; Guinan, Edward F.; Fadda, Dario +12 more
We report NASA-DLR SOFIA upGREAT circumstellar [O I] 63.2 µm and [C II] 157.7 µm emission profiles and FIFI-LS [O I] 63.2 µm, [O I] 145.5 µm, and [C II] 157.7 µm fluxes obtained shortly after Betelgeuse's 2019/2020 Great Dimming event. Haas et al. noted a potential correlation between the [O I] 63.2 µm flux and …