FROM SHOCK BREAKOUT TO PEAK AND BEYOND: EXTENSIVE PANCHROMATIC OBSERVATIONS OF THE TYPE Ib SUPERNOVA 2008D ASSOCIATED WITH SWIFT X-RAY TRANSIENT 080109

Journal Article · Tue Sep 01 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/702/1/226; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21333846

Modjaz, M; Li, W; Butler, N; Chornock, R; Perley, D; Bloom, J S; Filippenko, A V; Kocevski, D; Poznanski, D; Foley, R J; Bouy, H ^[1]; Blondin, S ^[2]; Kirshner, R P; Hicken, M; Berlind, P; Blake, C H; Brown, W R; Challis, P ^[3]; Stringfellow, G S ^[4]

---

1. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
2. European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)
3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138 (United States)
4. Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389 (United States)

We present extensive early photometric (ultraviolet through near-infrared) and spectroscopic (optical and near-infrared) data on supernova (SN) 2008D as well as X-ray data analysis on the associated Swift X-ray transient (XRT) 080109. Our data span a time range of 5 hr before the detection of the X-ray transient to 150 days after its detection, and a detailed analysis allowed us to derive constraints on the nature of the SN and its progenitor; throughout we draw comparisons with results presented in the literature and find several key aspects that differ. We show that the X-ray spectrum of XRT 080109 can be fit equally well by an absorbed power law or a superposition of about equal parts of both power law and blackbody. Our data first established that SN 2008D is a spectroscopically normal SN Ib (i.e., showing conspicuous He lines) and showed that SN 2008D had a relatively long rise time of 18 days and a modest optical peak luminosity. The early-time light curves of the SN are dominated by a cooling stellar envelope (for {delta}t{approx}0.1-4 days, most pronounced in the blue bands) followed by {sup 56}Ni decay. We construct a reliable measurement of the bolometric output for this stripped-envelope SN, and, combined with estimates of E{sub K} and M{sub ej} from the literature, estimate the stellar radius R{sub *} of its probable Wolf-Rayet progenitor. According to the model of Waxman et al. and Chevalier and Fransson, we derive R {sup W07}{sub *} = 1.2 {+-} 0.7R{sub sun} and R {sup CF08}{sub *} = 12 {+-} 7 R{sub sun}, respectively; the latter being more in line with typical WN stars. Spectra obtained at three and four months after maximum light show double-peaked oxygen lines that we associate with departures from spherical symmetry, as has been suggested for the inner ejecta of a number of SN Ib cores.

• OSTI ID: 21333846
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 702; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BOLOMETERS
DATA ANALYSIS
GALAXIES
LUMINOSITY
NICKEL 56
OXYGEN
PULSE RISE TIME
RED SHIFT
SPHERICAL CONFIGURATION
SUPERNOVAE
TRANSIENTS
ULTRAVIOLET RADIATION
X RADIATION
X-RAY SPECTRA