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Atmospheric regimes and trends on exoplanets and brown dwarfs
Zhang, Xi
A planetary atmosphere is the outer gas layer of a planet. Besides its scientific significance among the first and most accessible planetary layers observed from space, it is closely connected with planetary formation and evolution, surface and interior processes, and habitability of planets. Current theories of planetary atmospheres were primaril…
The kinematical and space structures of IC 2391 open cluster and moving group with Gaia-DR2
Vereshchagin, S. V.; Chupina, N. V.; Postnikova, E. S. +3 more
The kinematical parameters, spatial shape and structure of the open cluster IC 2391 and the associated stellar stream are studied here using Gaia Data Release 2 (GDR2) astrometry data. The apex positions are determined for the open cluster IC 2391 (data taken from Cantat-Gaudin et al.) and for the kinematical stream's stars mentioned in Montes et …
Photometric investigation on the W-subtype contact binary V1197 Her
Soonthornthum, Boonrucksar; Zhou, Xiao
Multi-color light curves of V1197 Her were obtained with the 2.4 meter optical telescope at the Thai National Observatory and the Wilson-Devinney (W-D) program was used to model the observational light curves. The photometric solutions reveal that V1197 Her is a W-subtype shallow contact binary system with a mass ratio of q = 2.61 and a fill-out f…
Interplanetary consequences and geoeffectiveness of CME associated with major solar flare from NOAA AR 12673
Soni, Shirsh Lata; Gupta, Radhe Shyam; Verma, Pyare Lala
In this reported work, we study a major X-class flare (X9.3) that arose from NOAA Active Region (AR) 12673 on 2017 September 6, from 11:53 UT to 12:10 UT in multi-wavelength views. This event also produced a fast coronal mass ejection (CME). NOAA AR 12673 emerged at S09W30 on 2017 September 6 and grew rapidly to a large AR. On 2017 September 9, th…
Eclipsing binary XZ CMi in a hierarchical quadruple system
Zhu, Li-Ying; Wang, Zhi-Hua
The new complete BVRcIc light curves and spectra of the short-period eclipsing binary XZ CMi are presented. The results from the combined analysis based on the photometric and spectroscopic data show that XZ CMi is a near contact binary with the secondary component filling its critical Roche lobe while the primary filling 91%…
Investigation of near-contact semi-detached binary WUMi through observations and evolutionary models
Soydugan, Faruk; Soydugan, Esin; Aliçavuş, Fahri
W UMi is a near contact, semi-detached, double-lined eclipsing binary star with an orbital period of 1.7 d. Simultaneous analysis of new BV R multi-color light curves and radial velocity data yields the main astrophysical parameters of the binary and its component stars. We determined mass and radius to be M1 = 3.22 ± 0.08 M⊙…
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…
Local galaxies with compact cores as the possible descendants of massive compact quiescent galaxies at high redshift
Fan, Lu-Lu; Gao, Ying
In order to test a possible evolutionary scenario of high-z compact quiescent galaxies (cQGs) that they can survive as local compact cores embedded in local massive galaxies with different morphology classes, we explore the star formation histories of local compact cores according to their spectral analysis. We build a sample of 182 massive galaxi…
Three new late-type hypervelocity star candidates from Gaia DR2 with refined selection criteria
Kupfer, Thomas; Liu, Chao; Jiang, Deng-Kai +6 more
Several dozen hypervelocity star (HVS) candidates have been reported based on the second data release of Gaia (Gaia DR2). However, it has been proven that the radial velocities of some Gaia HVS candidates are not reliable. In this paper, we employ refined astrometric criteria to re-examine Gaia DR2, arriving at a more reliable sample of HVS and hi…
Co-evolution of nuclear rings, bars and the central intensity ratio of their host galaxies
Ravikumar, C. D.; Aswathy, S.
Using a sample of 13 early-type spiral galaxies hosting nuclear rings, we report remarkable correlations between the properties of the nuclear rings and the central intensity ratio (CIR) of their host galaxies. The CIR, a function of intensity of light within the central 1.5 and 3 arcsec region, is found to be a vital parameter in galaxy evolution…