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S-type Stars from LAMOST DR10: Classification of Intrinsic and Extrinsic Stars
Luo, A. -Li; Li, Yin-Bi; Li, Shuo +2 more
In this paper, we found 2939 S-type stars from LAMOST Data Release 10 using two machine-learning methods, and 2306 of them were reported for the first time. The main purpose of this work is to study how to divide S-type stars into intrinsic and extrinsic stars with photometric data and LAMOST spectra. Using infrared photometric data, we adopted tw…
Inaccuracies and biases of the Gaussian size deconvolution for extracted sources and filaments
Men'shchikov, A.
A simple Gaussian size deconvolution method is routinely used to remove the blur of observed images caused by insufficient angular resolutions of existing telescopes, thereby to estimate the physical sizes of extracted sources and filaments. To ensure that the physical conclusions derived from observations are correct, it is necessary to know the …
Structural analysis of open cluster Bochum 2
Pandey, Rakesh; Sharma, Saurabh; Panwar, Neelam +5 more
We present the results from our deep optical photometric observations of Bochum 2 (Boc2) star cluster obtained using the 1.3-m Devasthal Fast Optical Telescope along with archival photometric data from Pan-STARRS2/2MASS/UKIDSS surveys. We also used high-quality parallax and proper motion data from the Gaia Data Release 3. We found that the Boc2 cl…
Using machine learning to characterize solar wind driving of convection in the terrestrial magnetotail lobes
Glassmeier, Karl-Heinz; Halekas, Jasper S.; Haaland, Stein +2 more
In order to quantitatively investigate the mechanism of how magnetospheric convection is driven in the region of magnetotail lobes on a global scale, we analyzed data from the ARTEMIS spacecraft in the deep tail and data from the Cluster spacecraft in the near and mid-tail regions. Our previous work revealed that, in the lobes near the Moon's orbi…
Sudden Extreme Obscuration of a Sun-like Main-sequence Star: Evolution of the Circumstellar Dust around ASASSN-21qj
Kemper, Francisca; Ertel, Steve; Scicluna, Peter +6 more
ASASSN-21qj is a distant Sun-like star that recently began an episode of deep dimming events after no prior recorded variability. Here we examine archival and newly obtained optical and near-infrared data of this star. The deep aperiodic dimming and absence of previous infrared excess are reminiscent of KIC 8462852 ("Boyajian's Star"). The observe…
Spatially Resolved Properties of the GW170817 Host Galaxy
Li, Yubin; Mao, Jirong; Zhao, Yinghe +4 more
GW170817 is the unique gravitational-wave (GW) event associated with the electromagnetic (EM) counterpart GRB 170 817A. NGC 4993 is identified as the host galaxy of GW170817/GRB 170 817A. In this paper, we focus on the spatially resolved properties of NGC 4993. We present the photometric results from the comprehensive data analysis of the high spa…
Structure of a Quasi-parallel Shock Front
Zhang, Tielong; Gedalin, Michael; Walker, Simon N. +2 more
The aim of this study is to compare observations of the magnetic field structure of observed quasi-parallel collisionless shock fronts with the results obtained analytically. A two-fluid analytic model of the shock front structure was derived under the assumptions that the shock is stationary and planar. The ion and electron kinetic pressures were…
A Wide View of the Galactic Globular Cluster NGC 2808: Red Giant and Horizontal Branch Star Spatial Distributions
Rest, Armin; Mastrobuono-Battisti, Alessandra; Johnson, Christian I. +7 more
Wide-field and deep DECam multiband photometry, combined with HST data for the core of the Galactic globular cluster NGC 2808, allowed us to study the distribution of various stellar subpopulations and stars in different evolutionary phases out to the cluster tidal radius. We used the C ugi = (u - g) - (g - i) index to identify three …
Toward more accurate RR Lyrae metallicities
Kovacs, Geza; Jurcsik, Johanna
By using a large sample of fundamental mode RR Lyrae stars with published spectroscopic iron abundances and gravities, we point out the importance of correcting these abundances by using more accurate temporal gravities. For the 197 stars with multiple spectra, overall we find [Fe/H] standard deviations of 0.167 (as published), 0.145 (shifted by d…
Accelerated particle beams in a 3D simulation of the quiet Sun. Lower atmospheric spectral diagnostics
Rouppe van der Voort, L.; Carlsson, M.; Gudiksen, B. V. +2 more
Context. Nanoflare heating through small-scale magnetic reconnection events is one of the prime candidates to explain heating of the solar corona. However, direct signatures of nanoflares are difficult to determine, and unambiguous observational evidence is still lacking. Numerical models that include accelerated electrons and can reproduce flarin…