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BEER analysis of Kepler and CoRoT light curves - V. eBEER: extension of the algorithm to eccentric binaries
Mazeh, T.; Faigler, S.; Shahaf, S. +1 more
We present an extension of the BEER model for eccentric binaries - eBEER, approximating the BEaming, Ellipsoidal, and Reflection effects by harmonic series of the Keplerian elements of their orbit. As such, it can be a tool for fast processing of light curves for detecting non-eclipsing eccentric binary systems. To validate the applicability of th…
A Catalog of 531 White Dwarf Candidates in the Local Galactic Halo from Gaia Data Release 2
Kim, Bokyoung; Lépine, Sebastien; Medan, Ilija
We present a catalog of 531 white dwarf candidates that have large apparent transverse motions relative to the Sun ( ${v}_{T}\gt 200$ km s-1), thus making them likely members of the local Galactic halo population. The candidates were selected from the Gaia Data Release 2 and are located in a great circle with 20° width running across bo…
A Search for Transiting Planets in the Globular Cluster M4 with K2: Candidates and Occurrence Limits
Wallace, Joshua J.; Hartman, Joel D.; Bakos, Gáspár Á.
We perform a search for transiting planets in the NASA K2 observations of the globular cluster (GC) M4. This search is sensitive to larger orbital periods (P ≲ 35 days, compared to the previous best of P ≲ 16 days), and at the shortest periods, smaller planet radii (Rp ≳ 0.3 RJ, compared to the previous best of Rp …
Water vapour masers in long-period variable stars. II. The semi-regular variables R Crt and RT Vir
Engels, D.; Winnberg, A.; Brand, J.
Context. Water masers emitting at a radiofrequency of 22 GHz are often found in the circumstellar envelopes of evolved stars. We monitored the H2O maser emission of a larger sample of evolved stars of different types to study the maser properties as a function of stellar type.
Aims: We wish to understand the origin and evolution of…
Constraining the oblateness of transiting planets with photometry and spectroscopy
Serrano, L. M.; Barros, S. C. C.; Santos, N. C. +2 more
Rapid planetary rotation can cause the equilibrium shape of a planet to be oblate. While planetary oblateness has mostly been probed by examining the subtle ingress and egress features in photometric transit light curves, we investigate the effect of oblateness on the spectroscopic Rossiter-McLaughlin (RM) signals. We found that a giant planet, wi…
Irregular changes in Hα emission line of V423 Aur observed by LAMOST Medium-Resolution Spectrographs
Wu, Hong; Hsia, Chih-Hao; Shi, Jian-Rong +8 more
We obtained seven spectra of the Be star V423 Aur on 2017 Dec. 5 using the LAMOST Medium-Resolution Spectrograph with exposures from 600 to 1200 seconds. These spectra show the irregular Hα emission line profile variations (LPVs). In the seven spectra, from the 4th to 7th, the left part of Hα profile even shows excess. However, no variation can be…
The spatial distribution of circumstellar material of the wind-fed system GX 301-2
Gou, Lijun; Liu, Jiren; Zheng, Xueying
The distribution of the circumstellar material in systems of supergiant X-ray binaries (SgXBs) is complex and not well probed observationally. We report a detailed study of the spatial distribution of the Fe K α-emitting material in the wind-fed system GX 301-2, by measuring the time delay between the Fe K α line and the hard X-ray continuum (7.8-…
KIC 12268220: A δ Scuti Pulsating Star and an Active Protohelium White Dwarf in an Eclipsing Binary System
Liu, Jifeng; Gao, Qing; Ren, Juanjuan +4 more
We present a photometric, spectroscopic, asteroseismic, and evolutionary analysis of the Algol-type eclipsing binary KIC 12268220. We find the O'Connell effect and anticorrelated eclipse timing variations in the Kepler light curve, revealing the presence of large starspots. Radial velocities and atmospheric parameters are obtained from ground-base…
Formation of a tiny flux rope in the center of an active region driven by magnetic flux emergence, convergence, and cancellation
Cao, Wenda; Chen, Yao; Zheng, Ruisheng +2 more
Aims: Flux ropes are generally believed to be core structures of solar eruptions that are significant for the space weather, but their formation mechanism remains intensely debated. We report on the formation of a tiny flux rope beneath clusters of active region loops on 2018 August 24.
Methods: Combining the high-quality multiwavelength…
NuSTAR Observations and Multiwavelength Modeling of the High-redshift BL Lacertae Object 4FGL J2146.5-1344
Ajello, M.; Kaur, A.; Hartmann, D. +3 more
High synchrotron peak (HSP; ${\nu }_{\mathrm{sy}}^{\mathrm{pk}}\gt {10}^{15}$ Hz) BL Lac objects are some of the most extreme accelerators in the universe. Those found at high redshifts (z > 1) challenge our understanding of blazar evolution models and are crucial for cosmological measurements of the extragalactic background light. In this pape…