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Regular radial velocity variations in nine G- and K-type giant stars: Eight planets and one planet candidate
Izumiura, Hideyuki; Sato, Bun'ei; Yoshida, Michitoshi +9 more
We report the detection of radial velocity (RV) variations in nine evolved G- and K-type giant stars. The observations were conducted at Okayama Astrophysical Observatory. Planets or planet candidates can best explain these regular variations. However, a coincidence of near 280 d variability among five of them prevents us from fully ruling out ste…
A Vindication of the RR Lyrae Fourier Light Curve Decomposition for the Calculation of Metallicity and Distance in Globular Clusters
Arellano Ferro, A.
We report the mean metallicity and absolute magnitude of RR Lyrae stars in a sample of 37 globular clusters, calculated via the Fourier decomposition of their light curves and ad hoc semi-empirical calibrations, in an unprecedented homogeneous approach. This enabled a new discussion of the metallicity dependence of the horizontal branch (HB) lumin…
A White Dwarf-Main-sequence Binary Unveiled by Time-domain Observations from LAMOST and TESS
Liu, Jifeng; Zong, Weikai; Bai, Yu +16 more
We report a single-lined white dwarf-main-sequence binary system, LAMOST J172900.17+652952.8, which is discovered by the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST)'s medium-resolution time-domain surveys. The radial-velocity semi-amplitude and orbital period of the optical visible star are measured by using follow-up observ…
V0644 Ser: An Active Ultrashort Period Contact Binary Star
Zhu, Li-Ying; Xu, Hu-Shan; Thawicharat, Sarotsakulchai +1 more
The photometric solutions of the ultrashort period close binary V0644 Ser based on our new complete BVRI light curves are derived by the Wilson-Devininney code. The results show that V0644 Ser is a W-type shallow contact binary, and the third light was found in the R and I bands. Compared with the light curves in 2011, the amplitude variation of t…
Validation and Interpretation of a Three-dimensional Configuration of a Magnetic Cloud Flux Rope
Qiu, Jiong; Hu, Qiang; Jian, Lan K. +3 more
One strong magnetic cloud (MC) with a magnetic field magnitude reaching ~40 nT at 1 au during 2012 June 16-17 is examined in association with a preexisting magnetic flux rope (MFR) identified on the Sun. The MC is characterized by a quasi-three-dimensional (3D) flux rope model based on in situ measurements from the Wind spacecraft. The contents of…
News from Gaia on σ Ori E: A case study for the wind magnetic braking process
Eggenberger, P.; Meynet, G.; Mowlavi, N. +8 more
Context.σ Ori E, a massive helium B-type star, shows high surface rotation and a strong surface magnetic field, potentially challenging the process of wind magnetic braking.
Aims: The Gaia satellite provides an accurate distance to σ Ori E and confirms its membership to the σ Ori cluster. We account for these two key pieces of information in …
Dynamical orbital evolution scenarios of the wide-orbit eccentric planet HR 5183b
Blunt, Sarah; Mustill, Alexander J.; Davies, Melvyn B. +1 more
The recently discovered giant exoplanet HR5183b exists on a wide, highly eccentric orbit (a = 18 au, e = 0.84). Its host star possesses a common proper-motion companion which is likely on a bound orbit. In this paper, we explore scenarios for the excitation of the eccentricity of the planet in binary systems such as this, considering planet-planet…
Superflares on solar-like stars. A new method for identifying the true flare sources in photometric surveys
Solanki, S. K.; Shapiro, A. I.; Usoskin, I. +5 more
Context. Over the past years, thousands of stellar flares have been detected by harvesting data from large photometric surveys. These detections, however, do not account for potential sources of contamination such as background stars or small Solar System objects appearing in the same aperture as the primary target.
Aims: We present a new met…
Further Evidence for the Minifilament-eruption Scenario for Solar Polar Coronal Jets
Savcheva, Antonia; Moore, Ronald L.; Savage, Sabrina L. +4 more
We examine a sampling of 23 polar-coronal-hole jets. We first identified the jets in soft X-ray (SXR) images from the X-ray telescope (XRT) on the Hinode spacecraft, over 2014-2016. During this period, frequently the polar holes were small or largely obscured by foreground coronal haze, often making jets difficult to see. We selected 23 jets among…
On measuring the Hubble constant with X-ray reverberation mapping of active galactic nuclei
Ingram, Adam; García, Javier A.; Kara, Erin +8 more
We show that X-ray reverberation mapping can be used to measure the distance to type 1 active galactic nuclei (AGNs). This is because X-ray photons originally emitted from the 'corona' close to the black hole irradiate the accretion disc and are reemitted with a characteristic 'reflection' spectrum that includes a prominent ~6.4 keV iron emission …