[vsnet-outburst 7041] Four new SDSS CVs
Taichi Kato
tkato at kusastro.kyoto-u.ac.jp
Sun Sep 10 11:01:42 JST 2006
Four new SDSS CVs for monitoring. All but SDSS J103533.02+055158.3
show strong emission lines and are likely candidates for non-magnetic
dwarf novae. SDSS J103533.02+055158.3 is peculiar in many respects
(refer to the original article for details).
http://xxx.lanl.gov/abs/astro-ph/0609196
Title: VLT/FORS spectroscopy of faint cataclysmic variables
discovered by the Sloan Digital Sky Survey
Authors: John Southworth, B. T. Gaensicke, T. R. Marsh, D. de
Martino, P. Hakala, S. Littlefair, P. Rodriguez-Gil, P. Szkody
Comments: 15 pages, 13 figures, accepted for publication by MNRAS.
Data are available at this http URL and will be lodged with CDS
We present medium-resolution VLT/FORS2 spectroscopy of six
cataclysmic variables discovered by the Sloan Digital Sky Survey. We
determine orbital periods for SDSS J023322.61+005059.5 (96.08 +/-
0.09 min), SDSS J091127.36+084140.7 (295.74 +/- 0.22 min), SDSS
J103533.02+055158.3 (82.10 +/- 0.09 min), and SDSS
J121607.03+052013.9 (most likely 98.82 +/- 0.16 min, but the one-day
aliases at 92 min and 107 min are also possible) using radial
velocities measured from their H_alpha and H_beta emission lines.
Three of the four orbital periods measured here are close to the
observed 75--80 min minimum period for cataclysmic variables,
indicating that the properties of the population of these objects
discovered by the SDSS are substantially different to those of the
cataclysmic variables found by other means. Additional photometry of
SDSS J023322.61+005059.5 reveals a periodicity of approximately 60
min which we interpret as the spin period of the white dwarf,
suggesting that this system is an intermediate polar with a low
accretion rate. SDSS J103533.02+055158.3 has a period right at the
observed minimum value, a spectrum dominated by the cool white dwarf
primary star and exhibits deep eclipses, so is an excellent candidate
for an accurate determination of the parameters of the system. The
spectroscopic orbit of SDSS J121607.03+052013.9 has a velocity
amplitude of only 13.8 +/- 1.6 km/s, implying that this system has an
extreme mass ratio. From several physical constraints we find that
this object must contain either a high-mass white dwarf or a
brown-dwarf-mass secondary component or both.
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