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Most Rotational Variables Dominated by a Single Bright Feature Are α 2 CVn Stars
Heinze, A. N.; Huber, Mark E.; Flewelling, Heather
We previously reported a rare class of variable star light curves isolated from a sample of 4.7 million candidate variables from the ATLAS survey. Dubbed "UCBH" light curves, they have broad minima and narrow, symmetrical maxima, with typical periods of 1-10 days and amplitudes of 0.05-0.20 mag. They maintain constant amplitude, shape, and phase c…
A non-detection of red supergiant convection in Gaia
Kochanek, C. S.
Large-scale surface convection on red supergiants (RSGs) can lead to shifts in the photocentre of the star that might be measured by Gaia and used as a new probe of the surface dynamics of these rare but important stars. Unlike brightness variations, photocentre motions would provide information on the physical scale of the convective cells. The s…
Electrostatic Plasma Wave Excitations at the Interplanetary Shocks
Giacalone, Joe; Fraschetti, Federico; Singh, Manpreet
Over the last few decades, different types of plasma waves (e.g., the ion acoustic waves (IAWs), electrostatic solitary waves, upper/lower hybrid waves, and Langmuir waves) have been observed in the upstream, downstream, and ramp regions of the collisionless interplanetary (IP) shocks. These waves may appear as short-duration (only a few milliseco…
Evolutionary history of western Eos Chaos of Valles Marineris, Mars: Insights from morphological characteristics
Sinha, Rishitosh K.; Rajesh, V. J.; Sajinkumar, K. S. +2 more
The dynamics of aqueous processes within the Eos Chasma region in the trough of Valles Marineris on Mars have been attributed to a variety of Hesperian-aged landforms. We aim to improve the understanding of the geological characteristics of the western part of the Eos Chaos by investigating the morphological, topographical, and thermo-physical cha…
The Nature of Blue Stars with Mid-infrared Excesses in the Large Magellanic Cloud
Chu, You-Hua; Gruendl, Robert A.; Ishioka, Ryoko +3 more
We present low-resolution optical spectra and classifications of 92 blue objects with mid-infrared excesses in the Large Magellanic Cloud. The majority of these objects were selected with the criteria of U - B < 0 and V < 17 from the potential young stellar object (YSO) candidates in Gruendl & Chu (GC09), which were identified based on S…
Fundamental parameters and stellar mass function of four open clusters close to the galactic plane
Kowshik, Krishna Kumar; Sujatha, S.; Routh, Swati
In the context of understanding star formation in the galactic plane, we present the results from the analysis of four young open clusters using archival data from Gaia Data Release 3, the Two-Micron All Sky Survey (2MASS) and Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). The open clusters—[BDB2003]G085.25‑00.02, [BDS2003]48, …
Space astrometry
Perryman, Michael
Astrometry, the measurement of accurate star positions and motions, was first carried out from space by the European Space Agency's Hipparcos mission in the 1990s. Today, it is undergoing a particularly dramatic advance with ESA's ongoing Gaia mission, launched in 2013. I explain why star positions are of such importance in astronomy, and outline …
Magnetic flux rope: What is it?
Hu, Qiang
Magnetic flux rope, a type of magnetic field structure in space plasmas, has been studied for decades through both observational and theoretical means. We provide a brief report on our recent modeling study of its magnetic field configuration based on in-situ spacecraft measurements, focusing on those made for large-scale flux ropes in the interpl…
New Hot Subdwarf Variables from Gaia eDR3
Kupfer, Thomas; Kosakowski, Alekzander; Barlow, Brad N. +1 more
We present a search for new variable hot subdwarfs from Gaia eDR3 using the Zwicky Transient Facility DR9 and the 2.1 m Otto Struve Telescope at McDonald Observatory. We report the discovery of 22 HW Vir binaries, 24 reflection effect binaries, and 14 ellipsoidally modulated systems. Candidate selection for our high-speed observations was based on…
X-ray and optical observations of two AM Her type cataclysmic variables: V388 Peg and V1189 Her
Zengi̇n Çamurdan, Dicle
We present time-resolved photometry of a polar V388 Peg and a strong candidate polar V1189 Her observed by T100 telescope at TÜBİTAK National Observatory between June-August 2014 and their X-ray observations using Swift archival data obtained in Apr 2014 (V388 Peg) and in Nov 2011 (V1189 Her). These data were supplemented by archival CRTS, ZTF, AS…