Search Publications
A novel approach to detect line emission under high background in high-resolution X-ray spectra
Karovska, Margarita; Zhang, Xiangyu; Kashyap, Vinay +1 more
We develop a novel statistical approach to identify emission features or set upper limits in high-resolution spectra in the presence of high background. The method relies on detecting differences from the background using smooth tests and using classical likelihood ratio tests to characterize known shapes like emission lines. We perform signal det…
A different view of wind in X-ray binaries: the accretion disc corona source 2S 0921-630
Done, Chris; Tanimoto, Atsushi; Odaka, Hirokazu +1 more
Accretion disc coronae (ADC) sources are very high inclination neutron star or black hole binaries, where the outer accretion flow blocks a direct view of the central source. The weak observed X-ray emission is instead produced mainly by scattering of the intrinsic radiation from highly ionized gas surrounding the source, the ADC. However, the ori…
The Neptunian gravity estimated from the motion of Triton based on astrometric observations
Yuan, Ye; Yan, Jianguo; Wang, Bo +4 more
Context. Accurate gravity and ephemerides estimations for Neptune and its satellites are necessary for the forthcoming deep space exploration missions targeting its system. In addition, these estimations are also meaningful for the modeling of Neptune's interior and for solar system dynamics studies. The body of astrometric data concerning Triton …
Compositional properties of planet-crossing asteroids from astronomical surveys
Lazzarin, M.; Carry, B.; La Forgia, F. +8 more
Context. The study of planet-crossing asteroids is of both practical and fundamental importance. As they are closer than asteroids in the Main Belt, we have access to a smaller size range, and this population frequently impacts planetary surfaces and can pose a threat to life.
Aims: We aim to characterize the compositions of a large corpus of…
Probing the jet size of two black hole X-ray binaries in the hard state
Miller-Jones, J. C. A.; Tingay, S. J.; Strader, J. +5 more
Using multifrequency very long baseline interferometry (VLBI) observations, we probe the jet size in the optically thick hard state jets of two black hole X-ray binary (BHXRB) systems, MAXI J1820+070 and V404 Cygni. Because of optical depth effects, the phase-referenced VLBI core positions move along the jet axis of the BHXRB in a frequency-depend…
Low-density star cluster formation: discovery of a young faint fuzzy on the outskirts of the low-mass spiral galaxy NGC 247
Janz, Joachim; van Dokkum, Pieter G.; Forbes, Duncan A. +21 more
The classical globular clusters found in all galaxy types have half-light radii of rh ~ 2-4 pc, which have been tied to formation in the dense cores of giant molecular clouds. Some old star clusters have larger sizes, and it is unclear if these represent a fundamentally different mode of low-density star cluster formation. We report the…
Comparison of the particle flux measured by Liulin-MO dosimeter in ExoMars TGO science orbit with those calculated by models
Guo, Jingnan; Semkova, Jordanka; Benghin, Victor +10 more
The knowledge of the space radiation environment in spacecraft transition and in Mars vicinity is of importance for the preparation of the human exploration of Mars. ExoMars Trace Gas Orbiter (TGO) was launched on March 14, 2016 and was inserted into circular Mars science orbit (MSO) with a 400 km altitude in March 2018. The Liulin-MO dosimeter is…
GRB 080503: A Very Early Blue Kilonova and an Adjacent Nonthermal Radiation Component
Zhou, Hao; Jin, Zhi-Ping; Covino, Stefano +5 more
The temporal behavior of the very dim optical afterglow of GRB 080503 is at odds with the regular forward shock afterglow model and a sole kilonova component responsible for optical emission has been speculated in some literature. Here we analyze the optical afterglow data available in archive and construct time-resolved spectra. The significant d…
Looking for nebular He II emission south of the multiple-massive star system, HD 5980
Sander, A. A. C.; Wofford, A.; Peimbert, A. +1 more
The nebular He II λ1640 emission line is observed in star-forming galaxies out to large distances and can be used to constrain the properties of sources of He+-ionizing photons. For this purpose, it is crucial to understand which are the main stellar sources of these photons. In some nearby metal-poor starburst galaxies, nebular He II λ…
A Spectroscopic Analysis of a Sample of K2 Planet-host Stars: Stellar Parameters, Metallicities and Planetary Radii
Cunha, Katia; Smith, Verne V.; Howell, Steve B. +5 more
The physical properties of transiting exoplanets are connected with the physical properties of their host stars. We present a homogeneous spectroscopic analysis based on the spectra of FGK-type stars observed with the Hydra spectrograph on the WIYN telescope. We derived the effective temperatures, surface gravities, and metallicities, for 81 stars…