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