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An Investigation of Poorly Studied Open Cluster NGC 4337 Using Multicolor Photometric and Gaia DR2 Astrometric Data
Bisht, D.; Rangwal, Geeta; Yadav, R. K. S. +5 more
We present a comprehensive analysis (photometric and kinematical) of the poorly studied open cluster NGC 4337 using 2MASS, WISE, APASS, and Gaia DR2 databases. By determining the membership probabilities of stars, we identified the 624 most probable members with membership probability higher than 50% by using proper motion and parallax data taken …
Two Major Constraints on the Inner Radii of Accretion Disks
Zdziarski, Andrzej A.; De Marco, Barbara
The Stefan-Boltzmann law yields a fundamental constraint on the geometry of inner accretion disks in black hole X-ray binaries. It follows from considering the irradiating flux and the effective temperature of the inner parts of the disk, which implies that a strong quasi-thermal component with the average energy higher than that of a blackbody at…
TESS Reveals a Short-period Sub-Neptune Sibling (HD 86226c) to a Known Long-period Giant Planet
Butler, R. Paul; Torres, Guillermo; Barclay, Thomas +44 more
The Transiting Exoplanet Survey Satellite mission was designed to find transiting planets around bright, nearby stars. Here, we present the detection and mass measurement of a small, short-period (≈4 days) transiting planet around the bright (V = 7.9), solar-type star HD 86226 (TOI-652, TIC 22221375), previously known to host a long-period (∼1600 …
Discovery of the Optical Afterglow and Host Galaxy of Short GRB 181123B at z = 1.754: Implications for Delay Time Distributions
Cenko, S. B.; Berger, E.; Cucchiara, A. +19 more
We present the discovery of the optical afterglow and host galaxy of the Swift short-duration gamma-ray burst (SGRB) GRB 181123B. Observations with Gemini-North starting ≈9.1 hr after the burst reveal a faint optical afterglow with i ≈ 25.1 mag at an angular offset of 0"59 ± 0"16 from its host galaxy. Using grizYJHK observations, we measure a phot…
Probing the circumnuclear absorbing medium of the buried AGN in NGC 1068 through NuSTAR observations
Bauer, F. E.; Brandt, W. N.; Bianchi, S. +9 more
We present the results of the latest NuSTAR monitoring campaign of the Compton-thick Seyfert 2 galaxy NGC 1068, composed of four ∼50 ks observations performed between 2017 July and 2018 February to search for flux and spectral variability on time-scales from 1 to 6 months. We detect one unveiling and one eclipsing event with time-scales less than …
The M Supergiant High-mass X-Ray Binary 4U 1954+31
Habel, Nolan; Fekel, Francis C.; Hinkle, Kenneth H. +5 more
The X-ray binary 4U 1954+31 has been classified as a low-mass X-ray binary containing an M giant and a neutron star (NS). It has also been included in the rare class of X-ray symbiotic binaries. The Gaia parallax, infrared colors, spectral type, abundances, and orbital properties of the M star demonstrate that the cool star in this system is not a…
Loose Ends for the Exomoon Candidate Host Kepler-1625b
Angus, Ruth; Howard, Andrew W.; Kipping, David +2 more
The claim of an exomoon candidate in the Kepler-1625b system has generated substantial discussion regarding possible alternative explanations for the purported signal. In this work, we examine these possibilities in detail. First, the effect of more flexible trend models is explored, and we show that sufficiently flexible models are capable of att…
The distribution of relative proper motions of wide binaries in Gaia DR2: MOND or multiplicity?
Clarke, C. J.
We examine the distribution of on-sky relative velocities for wide binaries previously assembled from theGaia DR2 data and focus on the origin of the high-velocity tail of apparently unbound systems, which may be interpreted as evidence for non-Newtonian gravity in the weak field limit. We argue that this tail is instead explicable in terms of a p…
Do Statistical Models Capture the Dynamics of the Magnetopause During Sudden Magnetospheric Compressions?
Wild, J. A.; Milan, S. E.; Imber, S. M. +9 more
Under periods of strong solar wind driving, the magnetopause can become compressed, playing a significant role in draining electrons from the outer radiation belt. Also termed "magnetopause shadowing," this loss process has traditionally been attributed to a combination of magnetospheric compression and outward radial diffusion of electrons. Howev…
Elemental abundances of M dwarfs based on high-resolution near-infrared spectra: Verification by binary systems
Kuzuhara, Masayuki; Omiya, Masashi; Reiners, Ansgar +4 more
M dwarfs are prominent targets of planet search projects, and their chemical composition is crucial to understanding the formation process or interior of orbiting exoplanets. However, measurements of elemental abundances of M dwarfs have been limited due to difficulties in the analysis of their optical spectra. We conducted a detailed chemical ana…