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Anomalous Extinction toward NGC 1938
Milone, Antonino P.; Panagia, Nino; De Marchi, Guido
Intrigued by the extended red giant clump (RC) stretching across the color-magnitude diagram of the stars in a 50 × 50 pc2 region of the Large Magellanic Cloud (LMC) containing the clusters NGC 1938 and NGC 1939, we have studied the stellar populations to learn about the properties of the interstellar medium (ISM) in this area. The exte…
Prediction of the Sun's Coronal Magnetic Field and Forward-modeled Polarization Characteristics for the 2019 July 2 Total Solar Eclipse
Nandy, Dibyendu; Dash, Soumyaranjan; Bhowmik, Prantika +2 more
On 2019 July 2 a total solar eclipse—visible across parts of the Southern Pacific Ocean, Chile, and Argentina—enabled observations of the Sun's corona. The structure and emission characteristics of the corona are determined by underlying magnetic fields, which also govern coronal heating and solar eruptive events. However, coronal magnetic field m…
Variability in Proto-planetary Nebulae. VI. Multitelescope Light Curve Studies of Several Medium-bright (V = 13-15), Carbon-rich Objects
Lu, Wenxian; Hrivnak, Bruce J.; Henson, Gary +3 more
We present 10 years of new photometric monitoring of the light variability of five evolved stars with strong mid-infrared emission from surrounding dust. Three are known carbon-rich proto-planetary nebulae (PPNe) with F-G spectral types; the nature of the other two was previously unknown. For the three PPNe, we determine or refine the pulsation pe…
ASASSN-16oh: A Nova Outburst with No Mass Ejection—A New Type of Supersoft X-Ray Source in Old Populations
Kato, Mariko; Hachisu, Izumi; Saio, Hideyuki
ASASSN-16oh is a peculiar transient supersoft X-ray source without a mass-ejection signature in the field of the Small Magellanic Cloud. Maccarone et al. concluded that ASASSN-16oh is the first dwarf nova with supersoft X-ray that originated from an equatorial accretion belt on a white dwarf (WD). Hillman et al. proposed a thermonuclear runaway mo…
Near-ultraviolet detections of four dwarf nova candidates in the globular cluster 47 Tucanae
Wijnands, Rudy; Modiano, David; Parikh, Aastha S.
We investigate near-ultraviolet variability in the Galactic globular cluster (GC) 47 Tucanae (47 Tuc). This work was undertaken within the GC sub-project of the Transient UV Objects project, a programme which aims to find and study transient and strongly variable UV sources. Globular clusters are ideal targets for transient searches because of the…
Dependence of Dayside Electron Densities at Venus on Solar Irradiance
Pätzold, M.; Häusler, B.; Tellmann, S. +3 more
The ionosphere of Venus is a weakly ionized plasma layer embedded in the planet's upper atmosphere. Planetary ionospheres provide an excellent opportunity to study how our variable Sun affects the planets in our solar system. Because ionospheres are reservoirs from which atmospheric species can be lost to space, studying how ionospheres respond to…
KKH 22, the first dwarf spheroidal satellite of IC 342
Anand, Gagandeep S.; Shaya, Edward J.; Karachentsev, Igor D. +4 more
Aims: We present observations with the Advanced Camera for Surveys on the Hubble Space Telescope of the nearby dwarf spheroidal galaxy KKH 22 = LEDA 2807114 in the vicinity of the massive spiral galaxy IC 342.
Methods: We derived its distance of 3.12 ± 0.19 Mpc using the tip of red giant branch (TRGB) method. We also used the 6 m BTA spe…
Solar Total Eclipse of 21 August 2017: Study of the Inner Corona Dynamical Events Leading to a CME
Filippov, Boris; Koutchmy, Serge; Lefaudeux, Nicolas
Total solar eclipse (TSE) coronal large- and small-scale events were reported in the historical literature but a definite synoptic coverage was missing for studying a relationship with the more general magnetic context of the solar-disk. We here analyze temporal changes in the solar corona before, during, and after the total solar eclipse on 21 Au…
Ages of Dwarfs in the Solar Neighborhood: Considering C and O Enhancements
Wu, Yaqian; Chen, Yuqin; Bi, Shaolan +7 more
Precise stellar ages of stars are necessary to study the evolution of the Milky Way. The age determination is significantly affected by C and O abundances of stars due to their contribution to the overall metallicity and opacity. On the basis of C and O abundances derived from high-resolution observations, we determine the ages of 148 FGK-type dwa…
Ultradiffuse Galaxies in the Coma Cluster: Probing Their Origin and AGN Occupation Fraction
Bogdán, Ákos; Canning, Rebecca E. A.; Kovács, Orsolya E.
Ultradiffuse galaxies (UDGs) exhibit low surface brightness, but their optical extent is comparable to that of Milky Way-type galaxies. In this work, we utilize Chandra X-ray observations of 404 UDGs in the Coma cluster and address two crucial goals. First, we constrain the formation scenario of UDGs by probing the X-ray emission originating from …