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Bridging the ultraviolet and optical regions: Transformation equations between GALEX and UBV photometric systems
Bilir, S.; Ak, T.; Yontan, T. +6 more
We derive transformation equations between GALEX and UBV colours by using the reliable data of 556 stars. We present two sets of equations: as a function of (only) luminosity class and as a function of both luminosity class and metallicity. The metallicities are provided from the literature, while the luminosity classes are determined by using the…
2MASS J04435686+3723033 B: A Young Companion at the Substellar Boundary with Potential Membership in the β Pictoris Moving Group
Bowler, Brendan P.; Liu, Michael C.; Phillips, Caprice L. +2 more
We present a detailed characterization of 2MASS J04435750+3723031, a low-mass companion orbiting the young M2 star 2MASS J04435686+3723033 at 7"6 (550 au) with potential membership in the 23 Myr β Pictoris moving group (βPMG). Using near-infrared (NIR) spectroscopy of the companion from IRTF/SpeX, we have found a spectral type of M6 ± 1 and indica…
A systematic study of spiral density waves in the accretion discs of cataclysmic variables
Groot, P. J.; Steeghs, D.; Ruiz-Carmona, R.
Spiral density waves are thought to be excited in the accretion discs of accreting compact objects, including cataclysmic variable stars (CVs). Observational evidence has been obtained for a handful of systems in outburst over the last two decades. We present the results of a systematic study searching for spiral density waves in CVs, and report t…
NLTE C and O abundances in RR lyrae stars
Wallerstein, George; Korotin, Sergey A.; Huang, Wenjin +5 more
The high excitation levels that form the O I and C I lines seen in RR Lyrae stars have long been known not to obey local thermodynamic equilibrium (LTE) statistics. We have observed 21 RR Lyrae and related stars with the Apache Point Observatory echelle spectrograph on the 3.5-m telescope and, for the first time, have derived abundances using non-…
High-resolution Near-infrared Polarimetry and Submillimeter Imaging of FS Tau A: Possible Streamers in Misaligned Circumbinary Disk System
Henning, Thomas; Nakagawa, Takao; Terada, Hiroshi +56 more
We analyzed the young (2.8 Myr-old) binary system FS Tau A using near-infrared (H-band) high-contrast polarimetry data from Subaru/HiCIAO and submillimeter CO (J = 2-1) line emission data from Atacama Large Millimeter/submillimeter Array (ALMA). Both the near-infrared and submillimeter observations reveal several clear structures extending to ∼240…
Outflow from Outer-arm Starburst in a Grazing Collision between Galaxies
Brinks, Elias; Struck, Curtis; Elmegreen, Bruce G. +5 more
Gemini NIFS K-band spectra and Atacama Large Millimeter/submillimeter Array 12CO $J=1\to 0, HCO+, and 100 GHz continuum observations are used to study a bright starburst clump on an outer arm of the interacting galaxy NGC 2207. This clump emits 23% of the total 24 µm flux of the galaxy pair and has an optically opaque d…
High-resolution spectroscopy of detached solar-type eclipsing binaries observed during the Kepler K2 mission
Çakırlı, Ö.; Hoyman, B.
Solar-type stars in eclipsing binaries are proving to be a remarkable resource of knowledge for testing models of stellar evolution, as spectroscopic and photometric studies have opened up a window into their interiors. Until recently, many cases have been worked out with Kepler data. In an ongoing effort to elucidate this research, we examine fiv…
Correlating the non-linear time series and spectral properties of IGR J17091-3624: is it similar to GRS 1915+105?
Misra, Ranjeev; Adegoke, Oluwashina; Mukhopadhyay, Banibrata
Using the correlation integral method, we explore the non-linear properties of IGR J17091-3624 by comparing the underlying behaviour to GRS 1915+105. We find that while GRS 1915+105 is known to reveal a combination of fractal (or even chaotic) and stochastic behaviours depending on its temporal class, IGR J17091-3624 mostly shows stochastic behavi…
Identification of Possible Stellar Companions via Speckle Interferometry in a Sample of Be Stars
Borges Fernandes, M.; Guerrero, C. A.; Souza, T. B.
We present speckle interferometric measurements of Be stars made with the 1.60 m Perkin-Elmer telescope at the Pico dos Dias Observatory of the Laboratório Nacional de Astrofísica in Brazil. Using three different filters (V, R, and I), we obtained astrometric measurements for 23 stars, during three observing runs allocated in 2017 March, 2018 Apri…
A Search for Extra-tidal RR Lyrae in Globular Clusters NGC 5024 and NGC 5053
Riddle, Reed; Rusholme, Ben; Kaplan, David L. +9 more
Recently, Kundu et al. reported that the globular cluster NGC 5024 (M53) possesses five extra-tidal RR Lyrae. In fact, four of them were instead known members of a nearby globular cluster NGC 5053. The status of the remaining extra-tidal RR Lyrae is controversial depending on the adopted tidal radius of NGC 5024. We have also searched for addition…