15 research outputs found
TYC 8380-1953-1: Discovery of an RS CVn binary through the XMM-Newton slew survey
In this paper we report the discovery of the chromospherically active (RS CVn
type) binary TYC 8380-1953-1 through the XMM-Newton slew survey and present
results of our optical and X-ray follow-up. With a flux limit of erg cm s in the soft band ( keV), the
XMM-Newton slew has a similar sensitivity to the ROSAT All Sky Survey allowing
interesting sources to be identified by their long-term variability. Two
different types of stellar sources are detected in shallow X-ray surveys: young
stars (both pre-main and main sequence stars) and chromospherically active
binaries (BY Dra and RS CVn type systems). The discovery of stars in such
surveys and the study of their nature through optical follow-ups is valuable to
determine their spatial distribution and scale height in the Galaxy. Our
analysis shows that TYC 8380-1953-1 is a double-lined spectroscopic binary with
both components having similar spectral type (likely K0/2+K3/5) and luminosity.
With a typical coronal temperature for an RS CVn system ( keV)
and an X-ray luminosity in the keV energy band higher than erg\,s, TYC 8380-1953-1 lies among the most X-ray luminous RS
CVn binaries.Comment: Accepted for publication in the PASP. 18 pages, 10 figure
The possible detection of a binary companion to a Type Ibn supernova progenitor
We present late-time observations of the site of the Type Ibn supernova (SN) 2006jc, acquired with the Hubble
Space Telescope Advanced Camera for Surveys. A faint blue source is recovered at the SN position, with
brightness mF W 435 = 26.76 0.20, mF W 555 = 26.60 0.23 and mF W 625 = 26.32 0.19 mag, although there is
no detection in a contemporaneous narrow-band Ha image. The spectral energy distribution of the late-time source
is well-fit by a stellar-like spectrum (log 3.7 Teff > and log L L > 4), subject to only a small degree of reddening
—consistent with that estimated for SN 2006jc itself at early-times. The lack of further outbursts after the
explosion of SN 2006jc suggests that the precursor outburst originated from the progenitor. The possibility of the
source being a compact host cluster is ruled out on the basis of the source’s faintness; however, the possibility that
the late-time source may be an unresolved light echo originating in a shell or sphere of pre-SN dust (within a radius
1 pc) is also discussed. Irrespective of the nature of the late-time source, these observations rule out a luminous
blue variable as a companion to the progenitor of SN 2006jc
Young Stellar Clusters Containing Massive Young Stellar Objects in the VVV Survey
This is an author-created, un-copyedited version of an article published in The Astronomical Journal. IOP Publishing is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at: at doi: https://doi.org/10.3847/0004-6256/152/3/74. © 2016. The American Astronomical Society. All rights reserved. IOPScience PublishingThe purpose of this research is to study the connection of global properties of eight young stellar clusters projected in the Vista Variables in the Via Lactea (VVV) ESO Large Public Survey disk area and their young stellar object population. The analysis in based on the combination of spectroscopic parallax-based reddening and distance determinations with main sequence and pre-main sequence ishochrone fitting to determine the basic parameters (reddening, age, distance) of the sample clusters. The lower mass limit estimations show that all clusters are low or intermediate mass (between 110 and 1800 Mo), the slope Gamma of the obtained present-day mass functions of the clusters is close to the Kroupa initial mass function. On the other hand, the young stellar objects in the surrounding cluster's fields are classified by low resolution spectra, spectral energy distribution fit with theoretical predictions, and variability, taking advantage of multi-epoch VVV observations. All spectroscopically confirmed young stellar objects (except one) are found to be massive (more than 8 Mo). Using VVV and GLIMPSE color-color cuts we have selected a large number of new young stellar object candidates, which are checked for variability and 57% are found to show at least low-amplitude variations. In few cases it was possible to distinguish between YSO and AGB classification on the basis of the light curves.Peer reviewedFinal Accepted Versio