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Orbital Elements of visual binary stars with very short arcs: With application to double stars from the 1829 southern double star catalog of James Dunlop
Letchford, Roderick R.; White, Graeme L.; Brown, Carolyn J.
Binary double stars are those whose binding energies are less than zero. Obtaining binary star orbits from short arcs has been a long-standing problem in astrophysics. A method is presented and tested here, which addresses the problem by using space-based astrometry, photometry, and astrophysical data, together with historic measures, to generate …
Ammonia in the interstellar medium of a starbursting disc at z = 2.6
Ivison, R. J.; Menten, K. M.; Dye, S. +4 more
We report the detection of the ground state rotational emission of ammonia, ortho-NH3 (JK = 10 → 00) in a gravitationally lensed intrinsically hyperluminous star-bursting galaxy at z = 2.6. The integrated line profile is consistent with other molecular and atomic emission lines which have resolved kinema…
Challenging the Disk Instability Model. I. The Case of YZ LMi
Baptista, Raymundo; Schlindwein, Wagner
Observations of YZ LMi show enhanced emission along the stream trajectory beyond impact at the disk rim during outbursts as well as when the quiescent disk is large. We investigated whether these features can be explained in terms of either gas stream overflow or penetration within the frameworks of the disk instability model (DIM) and the mass-tr…
Catalog of X-Ray Detected Be Stars (XDBS)
Kargaltsev, Oleg; Yang, Hui; Hare, Jeremy +2 more
We present a catalog of X-ray Detected Be Stars (XDBS) with 161 Be stars from the Be Star Spectra (BeSS) database having X-ray counterparts in the Chandra Source Catalog v2.0, XMM-Newton 4XMM-DR11 Catalog, or Swift 2SXPS Catalog. The multi-wavelength catalog includes accurate optical positions, X-ray properties (fluxes, photon indices and hardness…
Line Profile Studies of Coronal Active Regions in Fe XII λ195.12 Using Hinode/EIS
Raju, K. P.; Prabhakar, Maya
Coronal active regions are studied using Hinode/EIS observations in the EUV line Fe XII λ195.12 by analyzing their line profiles from 2006 December to 2019 December. The period covers the last 2 yr of solar cycle 23 and solar cycle 24 fully. Active regions are the main source of magnetic field in the solar atmosphere, important in its heating and …
Simulated SPHEREx spectra of asteroids and their implications for asteroid size and reflectance estimation
Doré, Olivier; Ivezić, Željko; Ivezić, Vedrana +6 more
We describe the construction and analysis of simulated SPHEREx spectra of Main Belt and Trojan asteroids. SPHEREx will deliver the first all-sky spectral survey at 96 spectral channels between 0.75 µm and 5.0 µm. We have developed a method for correcting SPHEREx asteroid spectra for intrinsic rotational variability that does not requir…
Analyzing Dominant 13.5 and 27 day Periods of Solar Terrestrial Interaction: A New Insight into Solar Cycle Activities
Saikia, Eeshankur; Syiemlieh, Rissnalin; Adhikary, Manashee +1 more
Our analysis presents an explanation of the Sun-Earth coupling mechanism during declining phase of a solar cycle, and how the dominant 13.5 and 27 day periods play roles in the coupling mechanism which led to intense terrestrial magnetic storms during this declining phase compared to the rising phase of a solar cycle. Moreover, it is observed that…
Insight-HXMT measurements of the diffuse X-ray background
Zhang, J.; Cui, W.; Zhang, S. +8 more
We present an X-ray spectrum of the diffuse X-ray background (DXRB) between 1.5 and 120 keV, as measured with the Low-Energy Detector (LE) and the High-Energy Detector (HE) aboard the Insight-HXMT satellite, based on 'blank-sky' observations. LE covers a nominal energy range of 1-15 keV and HE 20-250 keV, but calibration issues and data quality na…
Reconstructing AGN X-ray spectral parameter distributions with Bayesian methods. I. Spectral analysis
Paltani, Stéphane; Eckert, Dominique; Ge, Lingsong
X-ray spectra of active galactic nuclei (AGN) consist of several different emission and absorption components. To determine the spectral parameters, these components are often fitted manually with models chosen on a case-by-case basis. However, this approach has two problems. First, it becomes very hard for a survey with a large number of sources.…
A possible large-scale alignment of galaxy spin directions - Analysis of 10 datasets from SDSS, Pan-STARRS, and HST
Shamir, Lior
Multiple observations made by several different telescopes have shown asymmetry between the number of spiral galaxies rotating in opposite directions in different parts of the sky. One of the immediate questions regarding the possible asymmetry of the spin directions is whether the distribution forms a cosmological-scale axis. This paper analyzes …