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NSV 1440: first WZ Sge-type object in AM CVn stars and candidates
Nogami, Daisaku; Myers, Gordon; Monard, Berto +5 more
In 2015 and 2017, the AM CVn candidate NSV 1440 showed superoutbursts that had the characteristic features of WZ Sge-type dwarf novae (DNe). By analogy with hydrogen-rich cataclysmic variables (CVs), we can interpret these outbursts as "double superoutbursts" which are composed of a first superoutburst with early superhumps and a second superoutbu…
Radial Velocities, Space Motions, and Nearby Young Moving Group Memberships of Eleven Candidate Young Brown Dwarfs
Alam, Munazza K.; Faherty, Jacqueline K.; Cruz, Kelle L. +5 more
We present new radial velocity (RV) measurements for 11 candidate young very-low-mass stars and brown dwarfs, with spectral types from M7 to L7. Candidate young objects were identified by features indicative of low surface gravity in their optical and/or near-infrared spectra. RV measurements are derived from high-resolution (R =λ/Δλ = 20,000) J-b…
PPMXL and Gaia morphological analysis of Melotte 22 (Pleiades) and Melotte 25 (Hyades)
Elsanhoury, W. H.; Nouh, M. I.
In this article, we present a morphological study of two extended open clusters in the sky, Melotte 22 and Melotte 25 using J, H, and Ks photometry with Gaia DR2 and PPMXL proper motions. Various photometric and kinematic astrophysical parameters have been determined.
Based on proper motions of these clusters, we extract our member…Gaia 8: Discovery of a star cluster containing β Lyrae
Bastian, U.
Aims: The aim here is to try and clarify whether there are stars in the neighbourhood of β Lyrae which are physically connected to the famous prototype eclipsing binary.
Methods: We scrutinised the astrometric and photometric data (from HIPPARCOS and Gaia DR2) of stars in a limited sky field around β Lyrae.
Results: A star cluster o…
Quantifying the Influence of Key Physical Processes on the Formation of Emission Lines Observed by IRIS. I. Non-equilibrium Ionization and Density-dependent Rates
Testa, Paola; Bradshaw, Stephen J.
In the work described here, we investigate atomic processes leading to the formation of emission lines within the Interface Region Imaging Spectrograph wavelength range at temperatures near 105 K. We focus on (1) non-equilibrium and (2) density-dependent effects influencing the formation and radiative properties of S IV and O IV. These …
Soft excess in the quiescent Be/X-ray pulsar RX J0812.4-3114
Ho, Wynn C. G.; Potekhin, Alexander Y.; Heinke, Craig O. +3 more
We report a 72 ks XMM-Newton observation of the Be/X-ray pulsar (BeXRP) RX J0812.4-3114 in quiescence (L_X ≈ 1.6× 10^{33} erg s^{-1}). Intriguingly, we find a two-component spectrum, with a hard power-law (Γ ≈ 1.5) and a soft blackbody-like excess below ≈1 keV. The blackbody component is consistent in kT with a prior quiescent Chandra observation …
Variable Warm Dust around the Herbig Ae Star HD 169142: Birth of a Ring?
Weigelt, Gerd; Moór, Attila; Kóspál, Ágnes +7 more
The Herbig Ae star HD 169142 is known to have a gaseous disk with a large inner hole, and also a photometrically variable inner dust component in the sub-astronomical-unit region. Following up on our previous analysis, we further studied the temporal evolution of inner dust around HD 169142, which may provide information on the evolution from late…
Variable Hard X-Ray Emission from the Central Star of the Eskimo Nebula
Toalá, Jesús A.; Guerrero, Martín A.; Chu, You-Hua
The central star of NGC 2392 shows the hardest X-ray emission among central stars of planetary nebulae (CSPNe). The recent discovery of a spectroscopic companion with an orbital period of 1.9 days could provide an explanation for its hard X-ray emission, as well as for the collimation of its fast outflow. Here, we analyze the available Chandra and…
Near-infrared Variability of Low-mass Stars in IC 1396A and Tr 37
Rieke, G. H.; Hodapp, Klaus W.; Meng, Huan Y. A. +5 more
We have monitored nearly a square degree in IC 1396A/Tr 37 over 21 epochs extending over 2014-2016 for sources variable in the JHK bands. In our data, 65% ± 8% of previously identified cluster members show variations, compared with ≲0.3% of field stars. We identify 119 members of Tr 37 on the basis of variability, forming an unbiased sample down t…
Progressive steepening of the SNR RX J1713.7-3946 X-ray spectrum from XMM-Newton to INTEGRAL
Churazov, Eugene; Krivonos, Roman; Kuznetsova, Ekaterina +2 more
In this work, we present the first detailed analysis of the supernova remnant RX J1713.7-3946 in the hard X-ray energy range with the Imager on Board the INTEGRAL Satellite (IBIS) coded-mask telescope onboard the INTEGRAL observatory. The shell-type morphology of the entire remnant is mapped in hard X-rays for the first time and significantly dete…