MBCAA Observatory

VV Pup: polar variations

Observed: 13 Jan, 2, 15, 20 Feb, 30 Nov 2007

Michel Bonnardeau
29 Dec 2007

Abstract

This cataclysmic polar was observed in low state at the beginning of 2007. It was back to its usual level in November.

Introduction

VV Pup is a cataclysmic system, that is a binary with an accreting white dwarf. The white dwarf is strongly magnetized (about 10^8 gauss), its spin is synchronized with the orbital motion, and the accretion is funneled by the magnetic field (no accretion disk). This type of cataclysmic is a polar or an AM Her. The orbital/spin period is 100.44 mn.

This is a follow up of my 2006 observations.

January-February observations

VV Pup was observed with a 203mm SC telescope and a SBIG ST7E camera (KAF401E CCD). The comparison star is GSC6004-03141 with an assumed unfiltered magnitude of 13.0. For the only one V observation, the comparison star is LONEOS VV Pup Meech G with V=13.76. VV Pup could barely be detected with 200s exposures:

Date (UT) Mag Filter JD Heliocentric
correction (s) Phase

20070113.94229 <17.5 V 2,454,114.44229 368.60 0.42

20070209.84335 <16.9 C 2,454,141.34334 384.66 0.11

20070209.93169 <17.3 C 2,454,141.43169 384.57 0.38

20070215.94610 17.2+/-0.2 C 2,454,147.44610 376.15 0.61

20070220.82417 <16.7 C 2,454,152.32417 366.52 0.55

The phase is computed for a period of 0.069747d and 2,453,000.0 as the origin; in 2006 the pulsation maximum was then near phase 0.5.

November observations

In November, VV Pup was bright enough to carry out time-series. 49 images were obtained. The resulting light curve is:

Red: VV Pup, Blue: the check star shifted by +1.5mag. The error bars are +/- the 1 sigma statistical uncertainties.

The check star is UCAC2-24-322-717 at RA=08h15mn13.00s DEC=-19°02'14.7" observed with an average magnitude of 15.119, an average statistical uncertainty of 0.035mag and a standard deviation of 0.046mag.