Variable Interstellar Absorption Lines - some new programs using Yale-SMARTS CHIRON spectrograph for galactic astronomy research

Time-variable ISM lines - some notable papers Faison, et al 1998, Faison and Goss, using radio scintillation toward QSOs to detect small-scale structures (from Brogan, et al 2007)

Vidal-Majar et al, 1994; Chen, et al variability in circumstellar disks in Beta-Pic and 2 And systems emergence of new absorption on timescale of ~7 hours - interpreted as “comets” infalling into star

Blades, et al variability of HD Based on epochs of 1977 (NaI), 1984 (CaII), 1994 but with different spectrographs How does variability of CaII and NaI compare? Does this happen on shorter timescales?

Penprase, et al, variability of HD with 4 epochs new epoch of 1996 added to 1994 and 1984 date; also HST CI spectrum from 1997 added both spectra taken with AAT/UHRF; one NaI component dramatically weakens, one strengthens

Penprase, et al, variability of HD with 4 epochs new epoch of 1996 added to 1994 and 1984 date; also HST CI spectrum from 1997 added both spectra taken with AAT/UHRF; no change in CaII components; suggests photoionization of NaI in ISM

Na I Absorption Line Variability in Type Ia Supernovae (Patat, et al 2007; Science, 317, 924)

Simon, Gal Yam, Penprase et al, 2007 (Ap. J. 671, L25), NaI lines toward of Type Ia supernovae toward NGC 5584 no variability - constrains circumstellar material to M cs < 3 x M o

Further work on Type Ia supernovae: Simon et al, 2009, Ap. J 702, 1157 Na I lines shown to strengthen over timescales of 5-90 days Could be revealing clumpiness of ISM at scales of 0.02 pc as illuminated geometry varies

Variability of Type Ia supernova in M101 - SN 2011 fe (Nugent et al 2011; Nature, 480, 344)

high-velocity CaII, SiII and OI seen in absorption; lines strengthening in timescales of ~16 hours

M101 supernova - High-resolution Keck spectrum from SN 2011 fe (Penprase, et al 2012) intermediate velocity cloud at +125 could be associated with new SNR; additional epochs needed to detect variability

New Project – Local ISM absorption line spectra using CHIRON spectrograph at CTIO - can detect variability of ISM from old SN remnants and small clouds - provides fifth epoch for HD variable ISM observation - Can also give rapid spectroscopy for new Southern Hemisphere Supernovae

McDonald Observatory (2004) Yale/SMARTS CHIRON (2013) AAT UHRF (1996)

Yale/SMARTS CHIRON (2013) McDonald Observatory (2004) HD Na I D2 Profiles