Search Publications
System Parameters for the Eclipsing B-star Binary BD+11°3569
Gies, Douglas R.; Matson, Rachel A.; Williams, Stephen J. +4 more
We present the results from a combined spectroscopic and photometric in-depth study of the binary system BD+11o3569 (B4 V + B5 V). Fits to Johnson V, Cousins R C and I C photometry, and radial velocities yield an orbital period of 1.49712598 ± 0.00000020 days and an inclination of 82.°93 ± 0.°17. The combined l…
New Observations and Transit Solutions of the Exoplanets HAT-P-54b and WASP-153b
Ibryamov, S.; Petrov, N.; Kjurkchieva, D.
We present photometric observations of the newly-discovered transiting exoplanets HAT-P-54b and WASP-153b with the Rozhen 2 m telescope. As a result we improved their periods. The modeling of the new transits led to almost identical values of orbital inclinations and stellar radii to the first published values while the planet radii were slightly …
Intra-day variability of three Seyfert galaxies measured with XMM-Newton
Tripathi, Ashutosh; Gu, Min-Feng; Liao, Mai +2 more
We present and analyze the variability of three Seyfert galaxies on intra-day timescales. We have analyzed in a uniform manner the 38 longest (>30 ks) observations made for NGC 4051, MCG-06-30-15 and NGC 4151 by XMM-Newton between 2000 and 2015. The nuclei were quite active during essentially all of these observations and the overall X-ray flux…
Synoptic Studies of the Sun as a Key to Understanding Stellar Astrospheres
Gosain, Sanjay; Ichimoto, Kiyoshi; Suematsu, Yoshinori +11 more
Ground-based solar observations provide key contextual data (i.e., the "big picture") to produce a complete description of the only astrosphere we can study in situ: our Sun's heliosphere. This white paper outlines the current paradigm for ground-based solar synoptic observations, and indicates those areas that will benefit from focused attention.
Formation Mechanism of Contact Binary Asteroid (4179) Toutatis
Hu, S. C.
Contact binary asteroids are a kind of single asteroids with bifurcated (or bi-lobed) configurations. Ground-based radar observations have shown that about 14% of near-Earth asteroids larger than 200 meters in diameter may be contact binaries. Specially, the targets of the three minor planet missions, Hayabusa, Chang'e-2, and Rosetta, have contact…
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.