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Using Chandra Localizations and Gaia Distances and Proper Motions to Classify Hard X-Ray Sources Discovered by INTEGRAL
Hare, Jeremy; Fornasini, Francesca M.; Bodaghee, Arash +7 more
Here, we report on X-ray observations of ten 17-60 keV sources discovered by the International Gamma-Ray Astrophysics Laboratory satellite. The primary new information is sub-arcsecond positions obtained by the Chandra X-ray Observatory. In six cases (IGR J17040-4305, IGR J18017-3542, IGR J18112-2641, IGR J18434-0508, IGR J19504+3318, and IGR J200…
Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer
van Belle, Gerard T.; Schmitt, Henrique R.; Baines, Ellyn K. +9 more
We measured the angular diameters of 44 stars with the Navy Precision Optical Interferometer, obtaining uncertainties on the limb-darkened diameter of 2% or less for all but four stars. We then used our diameters with Gaia or Hipparcos parallaxes to calculate each star's physical radius. We gathered information from the literature to determine bol…
A Deep Study of an Intermediate-age Open Cluster SAI 35 (Juchert 20) Using Ground-based Imaging and Gaia EDR3 Astrometry
Bisht, D.; Rangwal, Geeta; Yadav, R. K. S. +4 more
We present a CCD UBVI photometric study of poorly studied intermediate-age open cluster SAI 35 (Juchert 20) for the first time. To accomplish this study, we also used LAMOST DR5, Two Micron All Sky Survey, and Gaia EDR3 databases. We identified 214 most probable cluster members with membership probability higher than 50%. The mean proper motion of…
Neutral-neutral synthesis of organic molecules in cometary comae
Charnley, S. B.; Cordiner, M. A.
Remote and in situ observations of cometary gases have revealed the presence of a wealth of complex organic molecules, including carbon chains, alcohols, imines, and the amino acid glycine. Such chemical complexity in cometary material implies that impacts by comets could have supplied reagents for prebiotic chemistry to young planetary surfaces. …
The Geographic Distribution of Dense-phase O2 on Ganymede
Brown, Michael E.; Trumbo, Samantha K.; Adams, Danica
Ground-based spectroscopy of Ganymede's surface has revealed the surprising presence of dense-phase molecular oxygen (O2) via weak absorptions at visible wavelengths. To date, the state and stability of this O2 at the temperatures and pressures of Ganymede's surface are not understood. Its spatial distribution in relation to …
Short-period Variability in the Globular Cluster NGC 419 and the SMC Field
Martínez-Vázquez, C. E.; Vivas, A. K.; Salinas, R.
Delta Scuti (δ Sct) stars have been extensively studied in our Galaxy but far less in extragalactic systems. Here we study the population of δ Sct variables in NGC 419, an intermediate-age globular cluster of the Small Magellanic Cloud (SMC), using g, r, and i Gemini-S/Gemini Multi-Object Spectrograph (GMOS) time-series observations. Our goal is t…
On the Collisional Disalignment of Dust Grains in Illuminated and Shaded Regions of IC 63
Soam, Archana; Andersson, B. -G.; Acosta-Pulido, Jose +5 more
Interstellar dust grain alignment causes polarization from UV to mm wavelengths, allowing the study of the geometry and strength of the magnetic field. Over the last couple of decades, observations and theory have led to the establishment of the radiative alignment torque mechanism as a leading candidate to explain the effect. With a quantitativel…
Orbital parameters of the hierarchical triplet system CN Lyn
Liao, WenPing; Qian, ShengBang; Li, LinJia
CN Lyn is an intriguing triplet system that contains three equal-mass components. However, the orbital parameters of this rare triple system are still unknown. By monitoring the system since 2016 October 19, 13 eclipse times have been obtained. We discover that the observed minus calculated (O - C) diagram of CN Lyn shows a cyclical variation with…
Geology and history of the Malea Planum region: A new view of Mars' oldest large volcanic province
Williams, David A.; Bernhardt, Hannes
Characterized by large paterae and late Noachian wrinkle-ridged plains, the ~1.2 million km2 Malea Planum region (MPR) has been grouped into a circum-Hellas volcanic province and likely represents the oldest of the large volcanic areas on Mars. Being key to Mars' early volcanic, tectonic, and climate evolution, we conducted a comprehens…
Titan in Transit: Ultraviolet Stellar Occultation Observations Reveal a Complex Atmospheric Structure
Tribbett, Patrick D.; Robinson, Tyler D.; Koskinen, Tommi T.
Transit spectroscopy is a key tool for exoplanet atmospheric characterization. However, transit spectrum observations can be limited by aerosol extinction when gas opacities are weak. The ultraviolet wavelength range contains a variety of strong molecular and atomic features, potentially enabling gas species detection even when atmospheric hazes a…