A Near-infrared Spectroscopic Study of the Accreting Magnetic White Dwarf Sdss J121209.31+013627.7 and Its Substellar Companion
نویسندگان
چکیده
The nature of the excess near-infrared emission associatedwith themagneticwhite dwarf commonly known as SDSS 1212 is investigated primarily through spectroscopy, and also via photometry. The inferred low-mass secondary in this system has been previously detected by the emission and variation of H , and the 1–2.5 m spectral data presented here are consistent with the presence of a late L or early T dwarf. The excess flux seen beyond 1.5 m in the phaseaveraged spectrum is adequately modeled with an L8 dwarf substellar companion and cyclotron emission in a 7 MG magnetic field. This interesting systemmanifests several observational properties typical of polars, and is most likely an old interacting binary with a magnetic white dwarf and a substellar donor in an extended low state. Subject headingg s: binaries: close — infrared: stars — novae, cataclysmic variables — stars: evolution — stars: formation — stars: fundamental parameters — stars: individual (SDSS J121209.31+013627.7) — stars: low-mass, brown dwarfs — white dwarfs
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