Name: jay farihi

Institution: gemini observatory

e-mail: jfarihi(no-spam)gemini.edu

Partner Contry: USA

Science Meeting: Yes

User Meeting: Yes

NGO Staff Meeting: No

Presentation: Yes

Format: Oral

Title: A Careful Near-Infrared Study of SDSS J121209.31 013627.7

Co-author: M.R. Burleigh D.W. Hoard

Co-authors' Institutions: University of Leicester Spitzer Science Center

Abstract :

The nature of the excess near-infrared emission associated with the magnetic white dwarf commonly known as SDSS 1212 is investigated through photometry and spectroscopy spanning the entire wavelength region. Although the substellar secondary in this system has been previously detected by the emission and variation of H$\alpha$, the $1-2.5$ $\mu$m spectrum presented here shows no definitive evidence of a late L or T dwarf. Rather, the excess flux seen beyond 1.5 $\mu$m in the phase-averaged spectrum may be completely consistent with cyclotron continuum emission alone. Given that both cyclotron emission and a hot accretion spot have been detected in this system, it appears that the near-infrared excess of SDSS 1212, at all phases, may be explained by cyclotron radiation of infalling electrons from its companion. The recent claim that the substellar companion was detected at near-infrared photometric minimum is highly uncertain and likely to be premature, and a more stringent upper limit on the spectral type of the secondary is established. It is suggested that a very deep mid-infrared observation may yield a direct detection of the substellar companion, thus providing a real constraint on its luminosity and temperature.