Detection of a Blue Point Source at the Location of Supernova 2011dh
ATel #6375; Gaston Folatelli (Kavli IPMU), Schuyler D. Van Dyk (IPAC/Caltech), Omar G. Benvenuto (IALP/UNLP), Melina C. Bersten (Kavli IPMU), Hanindyo Kuncarayakti (MAS/University of Chile), Keiichi Maeda (Kyoto University), Ken'ichi Nomoto (Kavli IPMU), Robert M. Quimby (SDSU)
on 7 Aug 2014; 19:28 UT
Credential Certification: Gaston Folatelli (gaston.folatelli@ipmu.jp)
Subjects: Optical, Ultra-Violet, Binary, Supernovae
We report Hubble Space Telescope (HST) observations of the field of
the Type IIb Supernova 2011dh in M51 performed with the Wide Field
Camera 3 (WFC3), UVIS channel and filters F225W and F336W on 2014
August 7.2 UT as part of our Cycle 21 program GO-13426 (PI:
G. Folatelli; joined with GO-13433, PI: J. Maund). The near-UV images
show the presence of a blue point source at the location of the
SN. We are confident that the new object is coincident with the fading
SN that Van Dyk et al. (2013, ApJ, 772, L32) identified in WFC3
images from 2013 to 0.07 UVIS pixel, or 2.8 milliarcsec (i.e., 0.1 pc
at the assumed distance of 8.4 Mpc for M51). Preliminary photometry
done with the Dolphot v2.0 (Dolphin 2000, PASP, 112, 1383) package
yielded flight-system magnitudes of F225W = 24.6 +/- 0.1 mag, and
F336W = 24.9 +/- 0.1 mag. The source's UV brightness and color is
compatible with it being the companion star of the disappeared yellow
supergiant progenitor (Van Dyk et al. 2013, ApJL, 772, L32; Ergon et
al. 2014, A&A, 562, 17). We estimate the flux from the SN ejecta to
be negligible in this wavelength range. If the contribution from an
unresolved light echo can be discarded, this detection provides
further confirmation for the interacting binary progenitor proposed by
Bersten et al. 2012, ApJ, 757, 31, and Benvenuto, Bersten, & Nomoto
2013, ApJ, 762, 74. More detailed analysis is ongoing.
