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A Very Long Baseline Array Trigonometric Parallax for RR Aql and the Mira Period-Luminosity Relation
Sun, Yan; Reid, Mark J.; Zhang, Bo +4 more
We report Very Long Baseline Array observations of 22 GHz H2O and 43 GHz SiO masers toward the Mira variable RR Aql. By fitting the SiO maser emission to a circular ring, we estimate the absolute stellar position of RR Aql and find agreement with Gaia astrometry to within the joint uncertainty of ≈1 mas. Using the maser astrometry we me…
Interplanetary Sheaths and Corotating Interaction Regions: A Comparative Statistical Study on Their Characteristics and Geoeffectiveness
Hajra, Rajkumar; Sunny, Jibin V.; Babu, Megha +1 more
Interplanetary sheaths and corotating interaction regions (CIRs), while having different solar sources, represent turbulent solar-wind plasma and magnetic field that can perturb the Earth's magnetosphere. We explore long-term solar-wind measurements upstream of the Earth during Solar Cycle 24, from January 2008 to December 2019, to compare their s…
X-Ray Intraday Variability of the TeV Blazar Markarian 421 with XMM-Newton
Gupta, Alok C.; Gaur, Haritma; Ostrowski, Michał +4 more
Highly variable Markarian 421 is a bright high-synchrotron energy peaked blazar showing a wide featureless nonthermal spectrum, making it a good candidate for our study of intraday flux and spectral variations over time. We analyze its X-ray observations over 17 yr, taken with the EPIC-pn instrument, to probe into the intraday variability properti…
The protoplanetary disc around HD 169142: circumstellar or circumbinary?
Pinte, C.; Ménard, F.; Bayo, A. +12 more
Stellar binaries represent a substantial fraction of stellar systems, especially among young stellar objects. Accordingly, binaries play an important role in setting the architecture of a large number of protoplanetary discs. Binaries in coplanar and polar orientations with respect to the circumbinary disc are stable configurations and could induc…
Hitting a New Low: The Unique 28 hr Cessation of Accretion in the TESS Light Curve of YY Dra (DO Dra)
Garnavich, Peter; Littlefield, Colin; Szkody, Paula +6 more
We present the Transiting Exoplanet Surveying Satellite light curve of the intermediate polar YY Draconis (YY Dra, also known as DO Dra). The power spectrum indicates that while there is stream-fed accretion for most of the observational period, there is a day-long, flat-bottomed low state at the beginning of 2020 during which the only periodic si…
Optical counterparts of ULXs in NGC 1672
Akyuz, A.; Allak, S.; Sonbas, E. +1 more
In this work, we deploy archival data from Hubble Space Telescope, Chandra, XMM-Newton, and Swift-XRT, to probe the nature of nine candidate ultraluminous X-ray sources (ULXs) in NGC 1672. Specifically, our study focuses on using the precise source positions obtained via improved astrometry based on Chandra and Hubble Space Telescope observations …
On the Evolution of Rotational Modulation Amplitude in Solar-mass Main-sequence Stars
Masuda, Kento
We investigate the relation between rotation periods P rot and photometric modulation amplitudes R per for ≈4000 Sun-like main-sequence stars observed by Kepler, using P rot and R per from McQuillan et al., effective temperature T eff from LAMOST DR6, and parallax data from Gaia EDR3. As has b…
Compositional Measurements of Saturn's Upper Atmosphere and Rings From Cassini INMS: An Extended Analysis of Measurements From Cassini's Grand Finale Orbits
Yelle, R. V.; Hörst, S. M.; Koskinen, T. T. +5 more
The Cassini spacecraft's final orbits sampled Saturn's atmosphere and returned surprisingly complex mass spectra from the Ion and Neutral Mass Spectrometer. Signal returned from the instrument included native Saturn species, as expected, as well as a significant amount of signal attributed to vaporized ices and higher mass organics believed to be …
Radio Emission from Binary Ultracool Dwarf Systems
Kao, Melodie M.; Pineda, J. Sebastian
Well-characterized binary systems will provide valuable opportunities to study the conditions that are necessary for the onset of both auroral and nonauroral magnetospheric radio emission in the ultracool dwarf regime. We present new detections of nonauroral "quiescent" radio emission at 4-8 GHz of the three ultracool dwarf binary systems GJ 564 B…
A multi-wavelength view of distinct accretion regimes in the pulsating ultraluminous X-ray source NGC 1313 X-2
Done, C.; Kaaret, P.; Soria, R. +7 more
NGC 1313 X-2 is one of the few known pulsating ultraluminous X-ray sources (PULXs), and so is thought to contain a neutron star that accretes at highly super-Eddington rates. However, the physics of this accretion remains to be determined. Here, we report the results of two simultaneous XMM-Newton and HST observations of this PULX taken to observe…