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Electron Densities and Nitrogen Abundances in Ionized Gas Derived Using [N II] Fine-structure and Hydrogen Recombination Lines
Lazio, T. Joseph W.; Horiuchi, Shinji; Goldsmith, Paul F. +7 more
We present a method for deriving the electron density of ionized gas using the ratio of the intensity of the [N II] 205 µm line to that of hydrogen radio recombination lines (RRLs). We use this method to derive electron densities of 21 velocity components in 11 lines of sight through the Galaxy, including the Galactic center. We observed, at…
Identification of Stellar Flares Using Differential Evolution Template Optimization
Kowalski, Adam F.; Wisniewski, John P.; Bellm, Eric C. +2 more
We explore methods for the identification of stellar flare events in irregularly sampled data of ground-based time domain surveys. In particular, we describe a new technique for identifying flaring stars, which we have implemented in a publicly available Python module called “PyVAN.” The approach uses the Differential Evolution algorithm to optimi…
New Constraint on the Atmosphere of (50000) Quaoar from a Stellar Occultation
Kobayashi, Naoto; Maehara, Hiroyuki; Matsunaga, Noriyuki +35 more
We report observations of a stellar occultation by the classical Kuiper Belt object (50000) Quaoar that occurred on 2019 June 28. A single-chord high-cadence (2 Hz) photometry data set was obtained with the Tomo-e Gozen CMOS camera mounted on the 1.05 m Schmidt telescope at Kiso Observatory. The obtained ingress and egress data do not show any ind…
Detection of nitrogen gas in the β Pictoris circumstellar disc
Snellen, I. A. G.; Lecavelier des Etangs, A.; Bourrier, V. +4 more
Context. The gas composition of the debris disc surrounding β Pictoris is rich in carbon and oxygen relative to solar abundances. Two possible scenarios have been proposed to explain this enrichment. The preferential production scenario suggests that the produced gas may be naturally rich in carbon and oxygen, while the alternative preferential de…
Circumstellar CO in metal-poor stellar winds: the highly irradiated globular cluster star 47 Tucanae V3
Zijlstra, A. A.; Richards, A. M. S.; Boyer, M. L. +4 more
We report the first detection of circumstellar CO in a globular cluster. Observations with ALMA have detected the CO J = 3-2 and SiO v = 1 J = 8 - 7 transitions at 345 and 344 GHz, respectively, around V3 in 47 Tucanae (NGC 104; [Fe/H] = -0.72 dex), a star on the asymptotic giant branch. The CO line is detected at 7σ at a rest velocity vLSR
CRTS J035010.7 + 323230, a new eclipsing polar in the cataclysmic variable period gap
Szkody, Paula; Mason, Paul A.; Wells, Natalie K. +2 more
We report the discovery of a new eclipsing polar, CRTS J035010.7+323230 (hereafter CRTS J0350+3232). We identified this cataclysmic variable (CV) candidate as a possible polar from its multiyear Catalina Real-Time Transient Survey (CRTS) optical light curve. Photometric monitoring of 22 eclipses in 2015 and 2017 was performed with the 2.1-m Otto S…
A young and obscured AGN embedded in the giant radio galaxy Mrk 1498
Jiménez-Andrade, E. F.; Ubertini, P.; Chavushyan, V. +10 more
Mrk 1498 is part of a sample of galaxies with extended emission-line regions (extended outwards up to a distance of ∼7 kpc) suggested to be photoionized by an AGN that has faded away or that is still active but heavily absorbed. Interestingly, the nucleus of Mrk 1498 is at the centre of two giant radio lobes with a projected linear size of 1.1 Mpc…
Evidence of a large-scale positive rotation-metallicity correlation in the Galactic thick disc
Lattanzi, Mario G.; Re Fiorentin, Paola; Spagna, Alessandro
This study is based on high quality astrometric and spectroscopic data from the most recent releases by Gaia and APOGEE. We select 58 882 thin and thick disc red giants in the Galactocentric (cylindrical) distance range 5 < R < 13 kpc and within |z| < 3 kpc, for which full chemo-kinematical information is available. Radial chemical gradie…
Member Stars of the GD-1 Tidal Stream from the SDSS, LAMOST, and Gaia Surveys
Huang, Y.; Chen, B. -Q.; Wang, C. +5 more
With the photometric data from the SDSS survey, the spectroscopic data from the SDSS/SEGUE and the LAMOST surveys, and the astrometric data from the Gaia DR2, we have identified 67 highly probable member stars of the GD-1 cold stellar stream spread along almost its entire length (i.e., from 126° to 203° in R.A.). With the accurate spectroscopic (i…
Carbon-deficient Red Giants
Bond, Howard E.
Carbon-deficient red giants (CDRGs) are a rare class of peculiar red giants, also called “weak G-band” or “weak CH” stars. Their atmospheric compositions show depleted carbon, a low {}12{{C}}{/}13{{C}} isotopic ratio, and an overabundance of nitrogen, indicating that the material at the surface has undergone CN-cycle hydrogen…