[vsnet-chat 7307] Four new SDSS CVs

[Taichi Kato]

   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.