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Observations of AR Sco with Chandra and AstroSat soft X-ray telescope
Singh, K. P.; Buckley, D. A. H.; Rana, V. +6 more
We present our AstroSat soft X-ray observations of a compact binary system, AR Sco, and analysis of its X-ray observations with Chandra that were taken only about a week before the AstroSat observations. An analysis of the soft X-ray (0.3–2.0 keV) data limits the modulation of the spin, orbital, or beat periods to less than 0.03 counts s
Changes in the Period of SU Sct, a Population II Cepheid
Berdnikov, L. N.; Pastukhova, E. N.
The reduction of all the available photometry for the Cepheid SU Sct has allowed its $O-C$ diagram spanning a time interval of 60 years to be constructed. Six abrupt changes in the period have been detected. The pulsation stability test proposed by Lombard and Koen (1993) has confirmed that the changes in the period are real. The absolute magnitud…
High-Resolution Spectroscopy of the B[e] Star MWC 645
Miroshnichenko, A. S.; Manset, N.; Zharikov, S. V. +4 more
Optical high-resolution spectroscopic observations of the emission-line star MWC645 are presented. The spectrum exhibits strong variable double-peaked Balmer emission lines as well as low-excitation emission lines of FeII, [FeII], and [OI] which are signatures of the B[e] phenomenon, while lines of helium have not been found. In addition to the em…
The star catalogue of Wilhelm IV, Landgraf von Hessen-Kassel. Accuracy of the catalogue and of the measurements
Verbunt, Frank; Schrimpf, Andreas
We analyse a manuscript star catalogue by Wilhem IV, Landgraf von Hessen-Kassel from 1586. From measurements of altitudes and of angles between stars, given in the catalogue, we find that the measurement accuracy averages 26″ for eight fundamental stars, compared to 49″ of the measurements by Brahe. The computation in converting altitudes to decli…
X-ray observations of the nova shell IPHASX J210204.7+471015
Estrada-Dorado, S.; Guerrero, M. A.; Toalá, J. A. +4 more
We present the analysis of XMM-Newton European Photon Imaging Camera (EPIC) observations of the nova shell IPHASX J210204.7+471015. We detect X-ray emission from the progenitor binary star with properties that resemble those of underluminous intermediate polars such as DQ Herculis (DQ Her): an X-ray-emitting plasma with temperature of TX
Dissecting the Strong-lensing Galaxy Cluster MS 0440.5+0204. II. New Optical Spectroscopic Observations in a Wider Area and Cluster Dynamical State
Limousin, Marceau; Carrasco, Eleazar R.; Ellingson, E. +5 more
We present an optical study of the strong-lensing galaxy cluster MS 0440.5+0204 at z = 0.19593, based on CFHT/MegaCam g', r' photometry and GMOS/Gemini and CFHT/MOS/SIS spectroscopy in a broader area than previous works. We have determined new spectroscopic redshifts for the most prominent gravitational arcs surrounding the central galaxy in the c…
Distances for the RR Lyrae Stars UU Ceti, UW Gruis, and W Tucanae
Parker, R.; Banks, T.; Parker, L. +2 more
B, V, i, and z bandpass observations were collected in late 2020 for three RRab type stars: UU Ceti, UW Gruis, and W Tucanae. The period-luminosity (PL) relationships of Catalen, Pritzl, and Smith (2004, ApJSupp, 154) and Caceres and Catelan (2008, ApJSuppl, 179) were applied to derive distances. These were found to be in reasonable agreement with…
Detecting and analysing geomorphological structures in images of comet 67P/Churyumov-Gerasimenko using Fourier transform
Schröter, Matthias; Boehnhardt, Hermann; Pack, Andreas +1 more
We present a method for automatized detection and analysis of quasi-periodic lineament structures from images at pixel precision. The method exploits properties of the images' frequency domain found by using the Fourier transform. We developed this method with the goal of detecting lineament structures in an image of the Hathor cliff of comet 67P/…
A Simple Technique for Identifying the Propagation Direction of CMEs in 3D Space
Fainshtein, V. G.; Egorov, Y. I.
By now several methods have been proposed enabling to determine the kinematic characteristics of coronal mass ejections (CMEs) in 3D space. Many of these methods are based on using the triangulation technique and stereoscopic observations of the CMEs with two and more spacecraft. As a rule, these methods involve relatively complicated procedures. …
To the Globular Cluster Classification Problem. Calculating the Concentration of Stars for 26 Clusters
Nuritdinov, S. N.; Tatjibaev, I. U.; Rastorguev, A. S.
In view of the absence of a satisfactory solution to the globular cluster (GC) classification problem, we have searched for a physical parameter that admits of the GC classification and finding empirical dependences on observed physical characteristics. For this purpose, we have considered a model of the apparent density in GCs with three free par…