Search Publications
New Variable Stars in NGC 6652 and Its Background Sagittarius Stream
Vivas, A. Katherina; Salinas, Ricardo; Contreras Ramos, Rodrigo
We conducted a variable star search on the metal-rich Galactic globular cluster NGC 6652 using archival Gemini-S/Gemini Multiobject Spectrograph data. We report the discovery of nine new variable stars in the NGC 6652 field, of which we classify six as eclipsing binaries and one as an SX Phoenicis star, leaving two variables without classification…
Phase-curve analysis of comet 67P/Churyumov-Gerasimenko at small phase angles
Lamy, P. L.; Lara, L. M.; Bertaux, J. -L. +31 more
Aims: The Rosetta-OSIRIS images acquired at small phase angles in three wavelengths during the fly-by of the spacecraft on 9-10 April 2016 provided a unique opportunity to study the opposition effect on the surface of comet 67P/Churyumov-Gerasimenko (67P). Our goal is to study phase curves of the nucleus at small phase angles for a variety of…
Photometric study of the open cluster NGC 381
Joshi, Y. C.; Maurya, J.
We present UBVRcIc photometry of stars, down to the 20th magnitude, in the region of the intermediate- age open cluster NGC 381. The core and the cluster radii are estimated to be 2.99 +/- 0.93 and 5.6 +/- 0.1 arcmin, respectively. A total of 350 probable cluster member stars are identified by using proper motion from GAIA as the criterion of memb…
SSA Analysis and Significance Tests for Periodicity in S, RS, SU, AD, BU, KK, and PR Persei
Chaplin, G. B.
Visual observations made by experienced observers are adjusted for individual observer bias. We examine the time series using signal processing methods to identify periodicities and test for the significance of the results finding a reliable periods in S Per, and to a limited extent in RS, SU, BU, and KK Per. Recommendations for future visual and …
Estimates of the Atmospheric Escape Rates of CH4 from Titan
Ip, Wing-Huen; Hsu, Jen-Kai
The upper atmosphere of Titan is highly variable as characterized by the variations of the thermospheric and exospheric temperatures from in situ measurements by Cassini at different Titan encounters. A related question has to do with the escape flux of CH4 that might also change with the complex plasma environment and ionospheric condi…
Reflection of the strahl within the foot of the Earth's bow shock
Goldstein, Melvyn L.; Gurgiolo, Christopher A.; Viñas, Adolfo
The reflection of a fraction of the solar wind at the bow shock to some extent defines the physical properties of what is known as the foreshock, the region where the interplanetary magnetic field has a direct connection to the bow shock. Both ion and electron reflection have been observed and together form a significant source of free energy that…
V348 And and V572 Per: Bright Triple Systems with Eccentric Eclipsing Binaries
Wolf, M.; Uhlař, R.; Zasche, P. +5 more
The eclipsing binaries are still important objects for our understanding of the universe. Especially these ones located within the more complex multiple systems can help us solving the problem of their origin and subsequent evolution of these higher order multiples. Photometry and spectroscopy spanning over more than 25 yr were used for the first …
Correlation Between Graben Orientation, Channel Direction Change, and Tectonic Loading: The Elysium Province, Mars
Kneller, B. D.; Roberts, G. P.; Grindrod, P. M.
We have investigated the links between regional stress fields, the volcanic centers, rifts, graben, and channels in the NW region of the Elysium Province (Figures a and b) to determine whether the sequence of stress events occurring during province development can be derived from the morphologies of these features, and thus provide a sequence of d…
Velocity Structure and Temperature Dependence of an Extreme-Ultraviolet Jet Observed by Hinode
Imada, S.; Kawai, T.; Kanda, N.
The acceleration mechanism of EUV and X-ray jets is still unclear. In general, there are two candidates for the mechanism. One is magnetic reconnection, and the other is chromospheric evaporation. We observed a relatively compact X-ray jet that occurred between 10:50 - 11:10 UT on 18 February 2011 by using the Solar Dynamics Observatory/Atmospheri…
Validation of a temperate fourth planet in the K2-133 multiplanet system
Poppenhaeger, K.; Wells, R.; Watson, C. A.
We present follow-up observations of the K2-133 multiplanet system. Previously, we announced that K2-133 contained three super-Earths orbiting an M1.5V host star - with tentative evidence of a fourth outer-planet orbiting at the edge of the temperate zone. Here, we report on the validation of the presence of the fourth planet, determining a radius…