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Young Stellar Distance Indicators and the Extragalactic Distance Scale
Anderson, R.
The extragalactic distance scale is perhaps the most important application of stellar distance indicators. Among these, classical Cepheids are high-accuracy standard candles that support a $1.4\%$ measurement of Hubble's constant, $H_0$. The accuracy of Cepheid distances is thus directly relevant for understanding the implications of the Hubble te…
The first photometric, period variation, and flare activity studies of TIC 24233294: Reviewing with the latest results of well-studied late-type active binaries
Jagirdar, Rukmini; Devarapalli, Shanti Priya; Pothuneni, Ravi Raja +2 more
In the current study, we present the first photometric, period variation, and flaring activity investigations of TIC 24233294. Additionally, we also review and report the flaring activity of five well-studied eclipsing binaries BX Tri, V405 And, GJ 3236, Thor 42, and GU Boo. Using the Transiting Exoplanet Survey Satellite (TESS) data, continuous v…
Probing the Magnetospheric Generator of Quiet Electrostatic Auroral Arcs From Ground Based Optical Observations and Magnetosphere-ionosphere Coupling Modeling
De Keyser, J.; Lamy, H.; Cessateur, G. +2 more
Observations of a quiet electrostatic auroral arc by the ALIS network on 5 March 2008 are used to infer a two-dimensional map of the flux of precipitating energy. Among a family of numerical solutions of a stationary magnetosphere—ionosphere coupling model in which the origin of the arc is a magnetospheric generator interface, we find which genera…
Physical Properties and Membership Determination of the Open Clusters IC 4665, NGC 6871 and Dzim 5 Through uvby − β Photoelectric Photometry
Peña, J. H.; Rentería, A.; Paredes, J. D. +1 more
uvby − β photoelectric photometry of stars in the direction of the open clusters IC 4665, NGC 6871 and Dzim 5 is presented. From this uvby − β photometry we classified the spectral types which allowed us to determine the reddening and, hence, the distance. Membership of the stars to the cluster was determined. Our results are compared with those o…
A small survey for massive stars in the LMC/SMC: binaries and pulsations
Çakırlı, Ömür; Hoyman, Barış; Özdarcan, Orkun
Binarity and pulsations are two notable properties that frequently appear together in massive stars. To place constraints on how binarity affects stellar evolution, the exact parameters of massive stars in binary systems must be known. Their exact and accurate masses and radii, which were calculated from binary dynamics, present model-independent …
Long term follow-up coverage of Gaia photometric alert sources by Ondrejov robotic telescopes
Jelínek, M.; Štrobl, J.; Hudec, R.
The robotic telescopes at the Ondrejov Observatory are providing long-term optical multi-color coverage for selected 25 Gaia alert triggers located in the northern sky hemisphere. I will present and briefly discuss examples of selected results, mostly unpublished, obtained with these devices. In addition to that, I will present and discuss the pot…
On orbit performance of the solar flare trigger for the Hinode EUV imaging spectrometer
Warren, Harry P.; Ugarte-Urra, Ignacio; Brooks, David H. +1 more
We assess the on-orbit performance of the flare event trigger for the Hinode EUV Imaging Spectrometer. Our goal is to understand the time-delay between the occurrence of a flare, as defined by a prompt rise in soft X-ray emission, and the initiation of the response observing study. Wide (266″) slit patrol images in the He II 256.32 Å spectral line…
Spectral Types of Long-Period Double-Lined Eclipsing Binary System Components from Low-Resolution Spectroscopy Data
Berdnikov, L. N.; Kniazev, A. Yu.; Malkov, O. Yu. +5 more
We present the results of spectral observations and consequent analysis of six long-period double-lined eclipsing binaries (DLEBs) with main-sequence (MS) components from a sample formed with the aim of testing the ''mass–luminosity'' relation (MLR) for stars in the
Evolution of brightness and magnetic features of young solar-type stars - II. The young F8 star HIP 71933
Hébrard, E. M.; Hughes, J. E.; Marsden, S. C. +4 more
The early, active history of our Sun is still not fully understood. Observations of the magnetic fields on active young solar-type stars allow us an insight into the early evolution of our Sun. Here we present Doppler and Zeeman-Doppler images of the young late-F star HIP 71933 (HD 129181) at multiple epochs to add to the growing data about the ev…
X-Ray Spectroscopy of Interstellar Carbon: Evidence for Scattering by Carbon-bearing Material in the Spectrum of 1ES 1553+113
Paerels, Frits; Staunton, John
Molecules and particles make up ~40%-70% of carbon in the interstellar medium, yet the exact chemical structure of these constituents remains unknown. We present carbon K-shell absorption spectroscopy of the Galactic interstellar medium obtained with the Low Energy Transmission Grating Spectrometer on board the Chandra Observatory that directly ad…