VARIABLE SODIUM ABSORPTION IN A LOW-EXTINCTION TYPE Ia SUPERNOVA,

By J. D. Simon, A. Gal-yam, O. Gnat, R. Quimby, M. Ganeshalingam, J. Silverman, S. Blondin, Weidong Li, A. Filippenko, J. Wheeler and 11 more. 2009

136 citations recorded by the source corpus.

Recent observations have revealed that some Type Ia supernovae exhibit narrow, time-variable Na i D absorption features. The origin of the absorbing material is controversial, but it may suggest the presence of circumstellar gas in the progenitor system prior to the explosion, with significant implications for the nature of the supernova (SN) progenitors. We present the third detection of such variable absorption, based on six epochs of high-resolution spectroscopy of the Type Ia supernova SN 2007le from the Keck I Telescope and the Hobby–Eberly Telescope. The data span a time frame of approximately three months, from 5 days before maximum light to 90 days after maximum. We find that one component of the Na i D absorption lines strengthened significantly with time, indicating a total column density increase of ∼2.5 × 1012 cm−2. The data limit the typical timescale for the variability to be more than 2 days but less than 10 days. The changes appear to be most prominent after maximum light rather than at earlier times when the ultraviolet flux from the SN peaks. As with SN 2006X, we detect no change in the Ca ii H and K absorption lines over the same time period, rendering line-of-sight effects improbable and suggesting a circumstellar origin for the absorbing material. Unlike the previous two supernovae exhibiting variable absorption, SN 2007le is not highly reddened (EB − V = 0.27 mag), also pointing toward circumstellar rather than interstellar absorption. Photoionization calculations show that the data are consistent with a dense (107 cm−3) cloud or clouds of gas located ∼0.1 pc (3 × 1017 cm) from the explosion. These results broadly support the single-degenerate scenario previously proposed to explain the variable absorption, with mass loss from a nondegenerate companion star responsible for providing the circumstellar gas. We also present possible evidence for narrow Hα emission associated with the SN, which will require deep imaging and spectroscopy at late times to confirm.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/681a0c10c54b3658affa2ea98f94f50f5da2a7b2

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In Astronomy and Astrophysics

1. E. Berger
2. D. Maoz
3. A. Filippenko
4. F. Mannucci
5. N. Smith
6. B. Metzger
7. Ryan Chornock
8. D. Kasen

In Nuclear and High Energy Physics

1. D. Maoz
2. F. Mannucci
3. D. Kasen
4. A. Gal-yam
5. G. Nelemans
6. A. Filippenko
7. N. Smith
8. R. Chevalier

Citations in the corpus

• THE LONG-TERM EVOLUTION OF DOUBLE WHITE DWARF MERGERS (2011, background): “Such an outflow could possibly explain the variable (e.g., Simon et al. 2009) or preferentially blueshifted (Sternberg et al. 2011) Na I D absorption lines seen in some SNe Ia, although further detailed study of the mass loss mechanism is necessary to make quantitative predictions.”
• The delay-time distribution of Type Ia supernovae from Sloan II (2012, background): “…seen in some C© 2012 The Authors Monthly Notices of the Royal Astronomical Society C© 2012 RAS Downloaded from https://academic.oup.com/mnras/article-abstract/426/4/3282/1017965 by guest on 30 July 2018 SN Ia spectra (Patat et al. 2007; Simon et al. 2009; Sternberg et al. 2011; Dilday et al. 2012).”
• Observational Clues to the Progenitors of Type Ia Supernovae (2013, background): “…(∼ 10 − 100 km s−1) absorption in the Na I D doublet (λλ5890, 5896) has been detected in the high-resolution, multi-epoch spectra of three SNe Ia (SN 2006X, Patat et al. 2007; SN 2007le, Simon et al. 2009; and the CSM-interacting case PTF11kx, Dilday et al. 2012, see Section 3.3.6, above).”
• TYPE Ia SUPERNOVAE STRONGLY INTERACTING WITH THEIR CIRCUMSTELLAR MEDIUM (2013, background): “…and subsequent recombination of circumstellar medium (CSM) has been observed in relatively normal SNe Ia (Patat et al. 2007; Blondin et al. 2009; Simon et al. 2009), and CSM has been detected in the spectra of at least 20% of SNe Ia in spiral galaxies (Sternberg et al. 2011) and has been linked…”
• Fourteen months of observations of the possible super-Chandrasekhar mass Type Ia Supernova 2009dc (2010, background): “Some SNe Ia exhibit narrow, time-variable Na I D absorption lines with unchanging, narrow Ca II H&K absorption (e.g. Simon et al. 2009).”
• EVLA OBSERVATIONS CONSTRAIN THE ENVIRONMENT AND PROGENITOR SYSTEM OF Type Ia SUPERNOVA 2011fe (2012, background): “Another intriguing constraint on the CSM surrounding SNe Ia comes from high-resolution optical spectroscopy, as observations of time-variable narrow Na I D absorption lines in the spectra of SNe Ia (Patat et al. 2007a; Blondin et al. 2009; Simon et al. 2009; Sternberg et al. 2011).”
• SPECTRA AND HUBBLE SPACE TELESCOPE LIGHT CURVES OF SIX TYPE Ia SUPERNOVAE AT 0.511 < z < 1.12 AND THE UNION2 COMPILATION (2010, background): “This model is potentially supported by detection (Patat et al. 2007; Simon et al. 2009; Blondin et al. 2009) of circumstellar material but also by color excess measurements for two of the best observed reddened SN Ia (Folatelli et al. 2010) being consistent with the expected extinction from…”
• ON THE SOURCE OF THE DUST EXTINCTION IN TYPE Ia SUPERNOVAE AND THE DISCOVERY OF ANOMALOUSLY STRONG Na i ABSORPTION (2013, background): “In a few such cases, temporal variations of blueshifted components of the Na i D lines apparently due to changing ionization conditions in the CSM have also been observed (e.g., Patat et al. 2007; Simon et al. 2009; Dilday et al. 2012).”
• Type-Ia Supernova Rates and the Progenitor Problem: A Review (2011, background): “A positive point for the SD model has been the variable NaD absorption that has been detected in the spectra of a few SNe Ia (Patat et al. 2007; Simon et al. 2009) and has been interpreted as circumstellar material from the companion.”