[vsnet-alert 17451] V418 Ser: another EI Psc-type object (ATEL)

Taichi Kato tkato at kusastro.kyoto-u.ac.jp
Fri Jul 4 17:42:39 JST 2014

V418 Ser: another EI Psc-type object (ATEL)

   (Please note that some of our recent papers have "special"
journal page numbers.  VSNET paper is PASJ 56, S1, where "S"
is for special volume.  Pdot paper is PASJ 61, S395.
An omission of "S" refers to a different paper, and ADS
fails to provide a link to the proper reference)


ATEL #6287                                                           ATEL #6287

Title:  V418 Ser: A Sub-Period Minimum CV With Hydrogen
Author: P. Garnavich, C. Littlefield (Notre Dame), D. Terndrup and
                S. Adams (Ohio State)
Queries:        pgarnavi at nd.edu
Posted: 3 Jul 2014; 16:43 UT
Subjects:Optical, Cataclysmic Variable

We obtained spectra of the cataclysmic variable V418 Ser, 
which was recently found by the VSNET collaboration 
(Kato et al. 2004, PASJ, 56, 1) to have an orbit 
shorter than the period minimum for hydrogen-rich 
CVs (Littlefield, VSNET-alert 17321; de Miguel, VSNET-alert 17322). 

The spectrum was taken with the Large Binocular 
Telescope (LBT) and MODS spectrograph on 2014 June 30, 
and covers wavelengths from 320 nm to 1 micron. The 
spectrum shows doubled peaked emission lines characteristic 
of a quiescent accretion disk. Hydrogen is clearly present 
indicating that this is not an AM CVn star,  but the 
Helium to Hydrogen ratio is large when compared with long 
period CVs. 

Overall the spectrum is very similar to the short period 
system SBS 1108+574 (CSS 120422:111127+571239; Littlefield 
et al. 2013, AJ, 145, 145; Carter et al. 2013, MNRAS, 431, 372) 
making V418 Ser a new member of a small but growing number of 
sub-period minimum binaries accreting some hydrogen. 

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