Search Publications
Radial Velocity Comparison of Gaia DR2 and RAVE DR5 Survey: A Systematic Offset in Radial Velocities among a Group of Highly Accurate Radial Velocity Stars
Deepak; Reddy, Bacham E.
Here, we report a comparative study of radial velocity (RV) data of two major surveys: Gaia Data Release 2 and RAVE Data Release 5. We restricted the sample to stars with relatively accurate RVs ({σ }RV}{Gaia}}≤slant 2 km s-1 or ≤2%, and {σ }RV}RAVE}}≤slant 2 km s-1 or ≤2%). The dif…
Kinematics of Type II Cepheids of the Galactic Halo
Wallerstein, George; Farrell, Elizabeth M.
In a step toward understanding the origin of the Galactic Halo, we have reexamined Type II Cepheids (T2C) in the field with new input from the second data release (DR2) of Gaia. For 45 T2C with periods from 1 to 20 days, parallaxes, proper motions, and [Fe/H] values are available for 25 stars. Only five show [Fe/H] < -1.5, while the remaining s…
Absolute Dimensions and Evolutionary Status of the Semi-detached Algol W Ursae Minoris
Koo, Jae-Rim; Hong, Kyeongsoo; Lee, Jae Woo +2 more
Double-lined eclipsing binaries allow accurate and direct determination of fundamental parameters such as mass and radius for each component, and they provide important constraints on the stellar structure and evolution models. In this study, we aim to determine a unique set of binary parameters for the Algol system W UMi and to examine its evolut…
Radial Velocity and Chemical Composition of Evolved Stars in the Open Clusters NGC 6940 and Tombaugh 5
D'Orazi, Valentina; Carraro, Giovanni; Baratella, Martina +1 more
We present and discuss medium resolution (R ∼ 13000), high signal-to-noise ({{S}}/{{N}}∼ 100), spectroscopic observations in the field of the open clusters NGC 6940 and Tombaugh 5. Spectra were recorded for seven candidate red giant stars in both clusters. For the latter, we present the very first chemical abundance analysis. We derive radial velo…
Spatially Resolved Sub-millimeter Continuum Imaging of Neptune with ALMA
Iino, Takahiro; Yamada, Takayoshi
This paper reports the result of spatially resolved 646 GHz sub-millimeter imaging observation of Neptune obtained by the Atacama Large Millimeter and sub-millimeter Array. The observation was performed in 2012 August as the flux calibration and synthesized beam size were small enough to resolve Neptune’s disk at this time. This analysis aims to c…
Disentangling Blended K2 Photometry: Determining the Planetary Host Star
Kane, Stephen R.; Ciardi, David R.; Carter, Brad +1 more
The presence of companion stars, whether bound or unbound, make correct identification of the planetary hosting star difficult when a planet has been detected through a photometrically blended transiting event. We present an approach that uses a combination of light curve analysis and stellar modeling to disentangle eight K2 photometrically blende…
CCD Measurements of Double and Multiple Stars at ASV and NAO Rozhen in 2016: Four Linear Solutions
Cvetković, Zorica; Pavlović, Rade; Boeva, Svetlana
The results of classical CCD observations for 371 double or multiple stars (450 pairs) obtained at both, Serbian Astronomical Station on the mountain of Vidojevica (ASV) and Bulgarian National Astronomical Observatory at Rozhen (NAOR) are presented. At ASV the observations were performed with the 0.6 m telescope in the first half of 2016 during 11…
The Albedos, Sizes, Colors, and Satellites of Dwarf Planets Compared with Newly Measured Dwarf Planet 2013 FY27
Sheppard, Scott S.; Fernandez, Yanga R.; Moullet, Arielle
2013 FY27 is the ninth intrinsically brightest Trans-Neptunian Object (TNO). We used ALMA at thermal wavelengths and Magellan in the optical to determine 2013 FY27's size and albedo for the first time and compare it to other dwarf planets. We found 2013 FY27 has a geometric albedo of {p}V={0.17}-0.030+0.045 and eff…
Infrared Photometric Study of Wolf-Rayet Galaxies
Chen, P. S.; Yang, X. H.; Liu, J. Y. +1 more
We collected observational data on 781 Wolf-Rayet (WR) galaxies from the literature to photometrically study their infrared properties measured by the 2MASS, WISE, IRAS, AKARI, and Herschel missions. It is found that in the 1-5 µm range the radiations of WR galaxies are dominated by the free-free emissions from the stellar winds and the circ…
Serendipitous X-Ray Sources in the Chandra HRC Field around Alpha Centauri
Ayres, Thomas R.
For more than a decade, Alpha Centauri AB (G2 V+K1 V) has been observed by Chandra, in a long-term program to follow coronal (T ∼ 106 K) activity cycles of the two sunlike stars. Over 2008.4-2017.8, 19 HRC-I exposures were taken, each about 10 ks in duration, and spaced about six months apart. Beyond monitoring the AB X-ray luminosities…