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Abundances from integrated spectra of 47 Tucanae (NGC 104)
Trevisan, M.; Barbuy, B.; Rennó, C. +1 more
47 Tucanae is among the most studied and observed globular clusters, given its proximity. The aim of this work is to study in detail the integrated spectrum of 47 Tucanae, as a template, in order to have a list of reliable lines that are validated for a moderate spectral resolution case. The spectrum of 47 Tucanae is reproduced by computing synthe…
The nature of the NGC 2546: Not one but two open clusters
González, J. F.; Veramendi, M. E.; Alejo, A. D.
Context. As part of a broader project on the role of binary stars in clusters, we present a spectroscopic study of the open cluster NGC 2546, which is a large cluster lacking previous spectroscopic analysis.
Aims: We report the finding of two open clusters in the region of NGC 2546. For the two star groups, we determine radial velocity, paral…
Identifying Exo-Earth Candidates in Direct Imaging Data through Bayesian Classification
Apai, Dániel; Bixel, Alex
Future space telescopes may be able to directly image between approximately 10 and 100 planets with sizes and orbits consistent with habitable surface conditions (“exo-Earth candidates” or EECs), but observers will face difficulty in distinguishing these from the potentially hundreds of nonhabitable “false positives” which will also be detected. T…
The Statistics of Extended Debris Disks Measured with Gaia and Planck
Jain, Bhuvnesh; Nibauer, Jacob; Baxter, Eric
Thermal emission from debris disks around stars has been measured using targeted and resolved observations. We present an alternative likelihood-based approach in which temperature maps from the Planck cosmic microwave background (CMB) survey at 857 and 545 GHz are analyzed in conjunction with stellar positions from Gaia to estimate the fraction o…
An extreme ultraluminous X-ray source X-1 in NGC 5055
Mondal, Samaresh; De Marco, Barbara; Różańska, Agata +1 more
Aims: We analysed multi-epoch X-ray data of the ultraluminous X-ray source NGC 5055 X-1, with luminosity up to 2.32 × 1040 erg s-1, to constrain the physical parameters of the source.
Methods: We performed a timing and spectral analysis of Chandra and XMM-Newton observations. We used spectral models that assume the …
Unusually low density regions in the compressed slow wind: Solar wind transients of small coronal hole origin
Farrugia, Charles J.; Wang, Linghua; Fu, Hui +5 more
We report on two small solar wind transients embedded in the corotating interaction region, characterized by surprisingly lower proton density compared with their surrounding regions. In addition to lower density, these two small solar wind transients showed other interesting features like higher proton temperature, higher alpha-proton ratios, and…
The Wind beneath My Wings. I. Spectral Types and Multiplicity of the Central Stars Supporting Stellar Bow Shock Nebulae
Kobulnicky, Henry A.; Dixon, Don M.; Schurhammer, Danielle P. +9 more
Arcuate mid-infrared nebulae known as stellar bow shock nebulae (SBNe) have been previously hypothesized to be supported by the strong stellar winds and/or luminosity of massive early-type stars. We present an optical spectroscopic survey of 84 stars identified from mid-infrared images as candidate SBN-supporting stars. Eighty-one of 84 sources, 9…
XMM-Newton and NICER Measurement of the Rms Spectrum of the Millihertz Quasiperiodic Oscillations in the Neutron-star Low-mass X-Ray Binary 4U 1636-53
Altamirano, D.; Méndez, Mariano; Zhang, Guobao +4 more
We used two XMM-Newton and six Neutron Star Interior Composition Explorer observations to investigate the fractional rms amplitude of the millihertz quasiperiodic oscillations (mHz QPOs) in the neutron-star low-mass X-ray binary 4U 1636-53. We studied, for the first time, the fractional rms amplitude of the mHz QPOs versus energy in 4U 1636-53 dow…
Search for the optical counterpart of the GW170814 gravitational wave event with the VLT Survey Telescope
Covino, S.; Campana, S.; Della Valle, M. +30 more
We report on the search for the optical counterpart of the gravitational event GW170814, which was carried out with the VLT Survey Telescope (VST) by the GRAvitational Wave Inaf TeAm. Observations started 17.5 h after the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo alert and we covered an area of 99 deg2 that en…
Evolving pulsation of the slowly rotating magnetic β Cep star ξ1 CMa
Handler, G.; Wade, G. A.; Pigulski, A. +11 more
Recent BRITE-Constellation space photometry of the slowly rotating, magnetic β Cep pulsator ξ1 CMa permits a new analysis of its pulsation properties. Analysis of the two-colour BRITE data reveals the well-known single pulsation period of 0.209 d, along with its first and second harmonics. A similar analysis of SMEI and TESS observation…