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Global and Local Three-dimensional Studies of The Residual Vector Field from 2MASS and Hipparcos-2 Catalog
Marco, F. J.; Martínez, M. J.; López, J. A.
The Gaia mission will provide a six-parameter solution for millions of stars, including a tridimensional map of our Galaxy. The estimation of distances has been made for the Tycho-Gaia Astrometric Solution (TGAS), while to contrast the proper motions it is interesting to consider positions from the different Gaia Data Release with older ones given…
Satellite observations of reconnection between emerging and pre-existing small-scale magnetic fields
Young, P. R.; Guglielmino, S. L.; Romano, P. +2 more
We report multi-wavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the unipolar plage of active region NOAA 12529. The photospheric configuration of the EFR is analyzed in detail benefitting from measurements …
Red supergiants in Galaxy and in galaxies
Kovaleva, D. A.
We use Gaia DR2 data to compare distribution of Milky Way red supergiants over absolute stellar magnitude M Ks with similar distributions produced by RSG's in other galaxies (M31, M33, LMC, SMC). In spite of their different metallicities, three galaxies: MW, M31 and SMC - provide similar distributions, while the RSG's from M33 and LMC are differen…
FUSE and IUE Spectroscopy of the Prototype Dwarf Nova ER Ursa Majoris During Quiescence
Sion, Edward M.; Godon, Patrick; Guzman, Giannina
ER Ursae Majoris is the prototype for a subset of SU UMa-type dwarf novae characterized by short cycle times between outburst, high outburst frequency, and negative superhumps. It suffers superoutbursts every 43 days, lasting 20 days, normal outbursts every 4 days, and has an outburst amplitude of 3 mag. We have carried out a far-ultraviolet (FUV)…
Multi-color Photometry of the Hot R Coronae Borealis Star and Proto-planetary Nebula V348 Sagittarii
Landolt, A. U.; Clem, J. L.
A long term program of precision photoelectric UBVRI photometry has been combined with AAVSO archival data for the hot, R CrB-type hydrogen deficient star and proto-planetary nebula, V348 Sgr. CCD data also are described. Since V348 Sgr is one of only four hot R CrB stars, it and other group members deserve continued attention by observers.
The neutron star mass and radius of Aql X‑1 from quiescent X‑ray emissions
Li, Z.; Luo, Y.
We report the quiescent spectra of neutron star (NS) in Aql X‑1 from XMM‑Newton and Chandra. The NS atmosphere model, NSATMOS, is applied to fit the quiescent spectra. The Monte Carlo Markov Chain algorithm is used to constrain the NS mass and radius in Aql X‑1. We find that the absolute flux calibration between XMM‑Newton and Chandra for Aql X‑1 …
Observation, Modern Light-curve Analysis, and 89 yr Period Study of the Short-period Algol, AE Cassiopeia
Caton, Daniel B.; Samec, Ronald G.; Chamberlain, Heather +1 more
AE Cas was observed some 40 yr ago by Srivastava & Kandpal and was analyzed by Kopal’s Fourier frequency -domain technique. No further precision observations have taken place until the present study, which represents the first modern synthetic analysis of light curves using the 2016 version of the Wilson-Devinney (W-D) Program. It was observed…
The Evolutionary Status of GK Subgiants
Abt, Helmut A.
Snowden & Young suggested that the reason why there are GK subgiants is because they are members of binaries, which would bring them above the main sequence in an Hertzsprung-Russell (HR) diagram. They studied a sample of 30 G0-K1 IV stars and were disappointed to find only two to be spectroscopic binaries. With more accurate radial velocities…
Angular resolution of HD, HIP and DM catalogues
Malkov, O. Yu.
We estimate angular resolution of HD, HIP and BD/CD/CpD catalogues and discuss problems of cross-identification of components of visual binary stars with these catalogues.
Probing the Bardeen-Petterson Effect in Tidal Disruption Events with Spectral line Reverberation Mapping
Dovčiak, Michal; Zhang, Wenda; Karas, Vladimír +1 more
For an inclined accretion flow around a rotating black hole, the combined effect of the Lense-Thirring precession and viscous torque tends to align the inner part of the flow with the black hole spin, leading to the formation of a warped disk, known as the Bardeen-Petterson (BP) effect. In tidal disruption events (TDEs) in which a supermassive bla…