Use of the BT2 water line list to determine the rotational temperature and H2O column density of the circumstellar envelope on five dates

BT2 is the most accurate and complete synthetic water line list in existence; it includes over 505 million transitions. BT2 spectra generated at various temperatures and column densities were fitted to observed H band spectra of V838 Mon recorded on 5 dates between 20 Nov. 2002 and 25 Dec. 2004. Five absorption features in the observed spectra were identified as being due to water. With one exception, where there was a single strong water line, all of the featues were blends of water lines. 17 individual water lines were assigned and the rotational temperatures and H2O column densities of the circumstellar ejected envelope were determined for each of the five dates

THE PECULIAR EXTINCTION LAW OF SN 2014J MEASURED WITH THE HUBBLE SPACE TELESCOPE

The wavelength dependence of the extinction of Type Ia SN 2014J in the nearby galaxy M82 has been measured using UV to near-IR photometry obtained with the Hubble Space Telescope, the Nordic Optical Telescope, and the Mount Abu Infrared Telescope. This is the first time that the reddening of an SN Ia is characterized over the full wavelength range of 0.2–2μm. A total-to-selective extinction, RV 3.1, is ruled out with high significance. The best fit at maximum using a Galactic type extinction law yields RV = 1.4 ± 0.1. The observed reddening of SN 2014J is also compatible with a power-law extinction, Aλ/AV = (λ/λV ) p as expected from multiple scattering of light, with p = −2.1 ± 0.1. After correcting for differences in reddening, SN 2014J appears to be very similar to SN 2011fe over the 14 broadband filter light curves used in our study