The peculiar type Ia supernova 1999by: Spectroscopy at early epochs

J. Vinkó, L. L. Kiss, B. Csák, G. Furész, R. Szabó, J. R. Thomson, S. W. Mochnacki

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We present medium-resolution (λ/Δλ ≈ 2500) optical spectroscopy of SN 1999by in NGC 2841 made around its light maximum. That the depth ratio of the two Si II features at 5800 and 6150 Å are R(Si II) ≈ 0.63 at maximum indicates that this SN belongs to the peculiar subluminous Type SNe Ia. Radial velocities inferred from the minimum of the 6150 Å trough reveal a steeper decline of the velocity curve than expected for normal SNe Ia, consistent with the behavior of published VRI light curves. A revised absolute magnitude of SN 1999by and distance to its host galaxy NGC 2841 are estimated based on the multicolor light-curve shape (MLCS) method, resulting in MV(max) = - 18.06 ± 0.1 mag and d = 17.1 ± 1.2 Mpc, respectively. An approximate linear dependence of the luminosity parameter Δ on R(Si II) is presented.

Original languageEnglish
Pages (from-to)3127-3132
Number of pages6
JournalAstronomical Journal
Issue number6
Publication statusPublished - Jun 1 2001


  • Stars: distances
  • Supernovae: general
  • Supernovae: individual (SN 1999by)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Vinkó, J., Kiss, L. L., Csák, B., Furész, G., Szabó, R., Thomson, J. R., & Mochnacki, S. W. (2001). The peculiar type Ia supernova 1999by: Spectroscopy at early epochs. Astronomical Journal, 121(6), 3127-3132.