V1432 Aql: 2012 observations

Observed: 1 Jun, 18, 25, 30 Jul, 7, 17 Aug, 14 Sep, 14, 15, 19 Nov 2012

Michel Bonnardeau
14 Dec 2012

Abstract

New observations of this asynchronous polar confirm the 2007-2011 observations.

Introduction

V1432 Aql is an asynchronous polar (a magnetized white dwarf accreting material from an orbiting companion) with a spin period slightly larger than the orbital period. I observed it in 2007-2011 and confirmed that the spin period is getting smaller (Bonnardeau (2012) hereafter B2012). Here I present new observations.

Observations

I observed V1432 with the same setup as in B2012. 483 images were obtained in 10 sessions The data may be downloaded from HERE. 8 eclipses are measured:

Eclipse min HJD -2,454,000	Uncertainty
2080.5920	0.0005
2127.570	0.002
2134.4425	0.0005
2147.3436	0.0002
2147.4840	0.0003
2157.4412	0.0002
2185.3465	0.0005
2251.2565	0.0005

and 4 spin minima:

Spin min HJD -2,454,000	Uncertainty
2080.580	0.005
2127.525	0.005
2134.414	0.003
2147.468	0.003

(The data of 30 July are not used because of the Moon).

Eclipse analysis

A best fit of the 8 eclipses reported here, my 29 2007-2011 observations and the 32 reported by Patterson et al (2005), weighted with the uncertainties, gives the ephemeris:

T₂ = 2,454,289.513,61 +/- 0.000,25 HJD
P₂ = 0.140,234,7720 +/- 0.000,000,0043 d

unchanged from my previous study.

The resulting O-C diagram:


Green: Patterson et (1995), Blue: Andronov et al (2006), Red: my data. Dash black line: best fit with my data and those of Patterson et al (1995).

Spin analysis

A best fit of the 4 spin minima reported here and of the 76 used in B2012, weighted with the uncertainties, using a derivative of the period, gives:

T_s = 2,449,638.3282 +/- 0.0020 HJD
P_s = 0.140,627,29 +/- 0.000,000,22 d
beta_s = -7.54*10^-10 +/- 0.06*10^-10 d

again unchanged from my previous study.

The average O-C is then:

average(O-C) = 105 +/- 514 s

And a best fit with a secondary derivative of the period gives:

T_2s = 2,449,638.3278 +/- 0.0019 HJD
P_2s = 0.140,628,45 +/- 0.000,000,09 d
beta_2s = -8.27*10^-10 +/- 0.03*10^-10 d
gamma_2s = 1.1*10^-15 +/- 0.1*10^-15 d

still unchanged from my previous study.

The average O-C is then:

average(O-C) = 56 +/- 475 s

The resulting O-C diagram:


Blue open circles: the data of Staubert et al.(2003), Green open squares: Mukai et al (2003), Brown dots: Andronov et al (2006), Red dots: my data. Blue line: the beta_2s*c² +gamma_2s*c³ function, Brown dot line: the beta_s*c² function.

References

Andronov I.L., Baklanov A.V., Burwitz V. (2006) A&A 452 941.

Bonnardeau M. (2012) OEJV 0153.

Mukai K., Hellier C., Madejski G., Patterson J. Skillman D.R. (2003) ApJ 597 479.

Patterson J., Skillman D.R., Thorstensen J., Hellier C. (1995) PASP 107 307.

Staubert R., Friedrich S., Pottschmidt K., Benlloch S., Schub S.L., Kroll P., Splittgerber E., Rothschild R. (2003) A&A 407 987.

Astronomical notes

V1432 Aql time keeping
2008 observations.

V1432 Aql: an asynchronous polar
2007 observations.

Technical notes

Telescope and camera configuration.

Computer and software configuration.

Data processing.