New Insights into the Environments of Novae from Chiron Spectroscopy

Tuesday, 09 December 2014 1 p.m. — 2 p.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
FREDERICK M. WALTER (Stony Brook University and NOAO South Visiting Astronomer)

Nearly 2 years ago I presented a CTIO colloquium on highlights of the first ten years of the Stony Brook/SMARTS Nova Program. In the past 2 years I have made exensive use of the Chiron echelle spectrograph on the 1.5m to obtain synoptic high resolution spectral coverage of bright novae, and nature cooperated with four bright novae: V1369 Cen, V745 Sco, N Sco 2014, and V5666 Sgr. This will be an update of the nova program, concentrating on lessons learned from the Chiron spectroscopy of 3 of these novae.

- V1369 Cen was a slow nova with multiple outbursts. Each minimum in the light curve coincides with the appearance of a new Na I absorption line system. This provides new insights into the mass loss mechanism in novae, and perhaps into how dust forms in nova envelopes.

- V745 Sco is a well-known recurrent nova with an M giant donor star. The 1.3m/Andicam light curve shows a strong ellipsoidal modulation. The optical spectra show that the He II 4686 line correlates with the appearance of the supersoft X-ray emission. The He and H absorption lines show a peculiar, never-before seen pattern of variable absorption that may be a useful probe of the circumstellar environment of this system.

- N Sco 2014 ia a fast He-N nova that appears nearly identical to V745 Sco, except that it never turned on in X-rays. Why?