High resolution spectroscopy of SN~2023ixf's first week: Engulfing the Asymmetric Circumstellar Material

Understand

We present a series of high-resolution echelle spectra of SN~2023ixf in M101, obtained nightly during the first week or so after discovery using PEPSI on the LBT.

• NaID absorption in these spectra indicates a host reddening of $E(B-V)$=0.031~mag and a systemic velocity of $+$7~km~s$^{-1}$ relative to the average redshift of M101.
• Dramatic changes are seen in in the strength and shape of strong emission lines emitted by CSM, including HeII4686, CIV5801,5811, H$\alpha$, and NIV7109,7123.
• In general, these narrow lines broaden to become intermediate-width lines before disappearing from the spectrum within a few days, indicating a limited extent to the dense CSM of around 20-30 AU (or $\la$10$^{14.7}$ cm).