Details

Autor(en) / Beteiligte

• Cartier, R
• Sullivan, M
• Firth, R E
• Pignata, G
• Mazzali, P
• Maguire, K
• Childress, M J
• Arcavi, I
• Ashall, C
• Bassett, B
• Crawford, S M
• Frohmaier, C
• Galbany, L
• Gal-Yam, A
• Hosseinzadeh, G
• Howell, D A
• Inserra, C
• Johansson, J
• Kasai, E K
• McCully, C
• Prajs, S
• Prentice, S
• Schulze, S
• Smartt, S J
• Smith, K W
• Smith, M
• Valenti, S
• Young, D R

Titel

Early observations of the nearby Type Ia supernova SN 2015F

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2017-02, Vol.464 (4), p.4476-4476

Ort / Verlag

London: Oxford University Press

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We present photometry and time series spectroscopy of the nearby Type Ia supernova (SN Ia) SN 2015F over -16 d to +80 d relative to maximum light, obtained as part of the Public ESO Spectroscopic Survey of Transient Objects. SN 2015F is a slightly sub-luminous SN Ia with a decline rate of ...m sub( 15)(B) = 1.35 plus or minus 0.03 mag, placing it in the region between normal and SN 1991bg-like events. Our densely sampled photometric data place tight constraints on the epoch of first light and form of the early-time light curve. The spectra exhibit photospheric C ii ...6580 absorption until -4 days, and high-velocity Ca ii is particularly strong at <-10 d at expansion velocities of ...23 000 km s super( -1). At early times, our spectral modelling with syn++ shows strong evidence for iron-peak elements (Fe ii, Cr ii, Ti ii, and V ii) expanding at velocities >14 000 km s super( -1), suggesting mixing in the outermost layers of the SN ejecta. Although unusual in SN Ia spectra, including V ii in the modelling significantly improves the spectral fits. Intriguingly, we detect an absorption feature at ~6800 A that persists until maximum light. Our favoured explanation for this line is photospheric Al ii, which has never been claimed before in SNe Ia, although detached high-velocity C ii material could also be responsible. In both cases, the absorbing material seems to be confined to a relatively narrow region in velocity space. The nucleosynthesis of detectable amounts of Al ii would argue against a low-metallicity white dwarf progenitor. We also show that this 6800 A feature is weakly present in other normal SN Ia events and common in the SN 1991bg-like sub-class. (ProQuest: ... denotes formulae/symbols omitted.)