Search Publications
VVV-WIT-07: another Boyajian's star or a Mamajek's object?
Minniti, D.; Saito, R. K.; Baptista, R. +6 more
We report the discovery of VVV-WIT-07, a unique and intriguing variable source presenting a sequence of recurrent dips with a likely deep eclipse in 2012 July. The object was found serendipitously in the near-IR data obtained by the VISTA Variables in the Vía Láctea (VVV) ESO public survey. Our analysis is based on VVV variability, multicolour, an…
An Ultraviolet-Optical Color-Metallicity Relation for Red Clump Stars Using GALEX and Gaia
Hogg, David W.; Hawkins, Keith; Schiminovich, David +3 more
Although core helium-burning red clump (RC) stars are faint at ultraviolet wavelengths, their ultraviolet (UV)-optical color is a unique and accessible probe of their physical properties. Using data from the Galaxy Evolution Explorer All Sky Imaging Survey, Gaia Data Release 2, and the Sloan Digital Sky Survey Apache Point Observatory Galactic Evo…
Stellar Parameters for Pulsating B-star Candidates in the Kepler Field
McSwain, M. Virginia; Hanes, Richard J.; Waskie, Steven +3 more
The field of asteroseismology has enjoyed a large swath of data coming from recent missions (e.g., CoRoT, Kepler, K2). This wealth of new data has allowed the field to expand beyond the previous limitation of a few extremely bright and evolved stars. Asteroseismology relies on accurate surface measurements for boundary conditions, but the predicte…
Not so different after all: properties and spatial structure of column density peaks in the pipe and Orion A clouds
Lombardi, Marco; Palau, Aina; Alfaro, Emilio +4 more
We present a comparative study of the physical properties and the spatial distribution of column density peaks in two giant molecular clouds (GMCs), the Pipe Nebula and Orion A, which exemplify opposite cases of star cluster formation stages. The density peaks were extracted from dust extinction maps constructed from Herschel/SPIRE far-infrared im…
Gaia DR2 white dwarfs in the Hercules stream
Rebassa-Mansergas, Alberto; Althaus, Leandro G.; Torres, Santiago +5 more
Aims: We analyzed the velocity space of the thin- and thick-disk Gaia white dwarf population within 100 pc by searching for signatures of the Hercules stellar stream. We aimed to identify objects belonging to the Hercules stream, and by taking advantage of white dwarf stars as reliable cosmochronometers, to derive a first age distribution.
A NuSTAR and XMM-Newton Study of the Two Most Actively Star-forming Green Pea Galaxies (SDSS J0749+3337 and SDSS J0822+2241)
Imanishi, Masatoshi; Tanimoto, Atsushi; Ueda, Yoshihiro +4 more
We explore X-ray evidence for the presence of active galactic nuclei (AGNs) in the two most actively star-forming Green Pea galaxies (GPs), SDSS J0749+3337 and SDSS J0822+2241, which have star formation rates (SFRs) of 123 M ⊙ yr-1 and 78 M ⊙ yr-1, respectively. The GPs have red mid-infrared (MIR) spectr…
Signature of Stochastic Acceleration and Cooling Processes in an Outburst Phase of the TeV Blazar ON 231
Gupta, Alok C.; Wiita, Paul J.; Kalita, Nibedita +1 more
We present a detailed spectral and temporal study of the intermediate-type blazar ON 231 during the TeV outburst phase in 2008 June with observations performed by Swift and XMM-Newton. The X-ray flux of the source, which was significantly dominated by the soft photons (below 3-4 keV), varies between 27% and 38% on day timescales, while mild variat…
Optical spectroscopic classification of 35 hard X-ray sources from the Swift-BAT 70-month catalogue
Palazzi, E.; Minniti, D.; Masetti, N. +15 more
The nature of a substantial percentage (about one fifth) of hard X-ray sources discovered with the BAT instrument onboard the Neil Gehrels Swift Observatory (hereafter Swift) is unknown because of the lack of an identified longer-wavelength counterpart. Without such follow-up, an X-ray catalogue is of limited astrophysical value: we therefore emba…
Gas phase SiO in the circumstellar environment of the recurrent nova T Coronae Borealis
Munari, U.; Gehrz, R. D.; Shahbandeh, M. +9 more
We report the discovery of the diatomic molecule SiO in the gas phase in the environment of the recurrent nova T Coronae Borealis. While some of the SiO is photospheric, a substantial portion must arise in the wind from the red giant component of T CrB. A simple fit to the SiO feature, assuming local thermodynamic equilibrium, suggests a SiO colum…
Accurate stellar parameters and distance to two evolved eclipsing binary systems, OGLE-BLG-ECL-123903 and OGLE-BLG-ECL-296596, towards the Galactic bulge
Soszyński, I.; Smolec, R.; Thompson, I. B. +15 more
Aims: Our aim is to obtain high-accuracy measurements of the physical and orbital parameters of two evolved eclipsing binary systems, and to use these measurements to study their evolutionary status. We also aim to derive the distances to the systems by using a surface brightness-colour relation and compare these distances with the measuremen…