Query : 2007A&A...466..589Q

2007A&A...466..589Q - Astronomy and Astrophysics, volume 466, 589-594 (2007/5-1)

Orbital period changes of the nova-like cataclysmic variable AC Cancri: evidence of magnetic braking and an unseen companion.


Abstract (from CDS):

The source AC Cnc is a nova-like cataclysmic variable containing a white-dwarf primary with a mass of 0.76M and a K2-type secondary with a mass of 0.77M. We intend to study its period changes and search for evidence of magnetic braking and unseen third body. The period changes were investigated based on the analysis of the O-C curve, which is formed by one new eclipse time together with the others compiled from the literature. A cyclic change with a period of 16.2yr was found to be superimposed on a long-term period decrease at a rate of {dot}(P)=-1.24(±0.44)x10–8days/year. It is shown that the mechanism of magnetic activity-driven changes in the quadrupole momentum of the secondary star (Applegate's mechanism) does not explain it easily. This period oscillation was plausibly interpreted by a light-travel time effect caused by the presence of a cool M-type dwarf companion (M3>0.097M) in a long orbit (16.2yr) around the binary. Since the masses of both components are nearly the same, the mass transfer from the lobe-filling secondary to the primary is not efficient to cause the continuous period decrease. It may be strong evidence of an enhanced magnetic stellar wind from the K2-type component. If the Alfen radius of the cool secondary is the same as that of the Sun (i.e., RA=15R), the mass-loss rate should be {dot}(M2)=-1.65x10–10M/year. By using the enhanced mass loss proposed by Tout & Eggleton (1988), the mass-loss rate should be {dot}(M2)=-1.18x10–9 M/year. In this case, the Alfen radius is determined to be RA=5.2R. However, the long-term decrease of the period may be only a part of a long-period (>100yr) oscillation caused by the presence of an additional body. To check the conclusions, new precise times of light minimum will be required.

Abstract Copyright:

Journal keyword(s): stars: novae, cataclysmic variables - stars: binaries: eclipsing - stars: individual: AC Cnc - stars: evolution - stars: mass-loss - stars: binaries: close

Simbad objects: 3

goto Full paper

goto View the references in ADS

Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 V* AC Cnc CV* 08 44 27.1121665272 +12 52 31.995783264   13.80 14.15     K1-3V 132 0
2 H 0850+13 X 08 53 +13.0           ~ 3 0
3 V* NN Ser CV* 15 52 56.1203524080 +12 54 44.429312196     16.51     DAO1+M4 262 0

To bookmark this query, right click on this link: simbad:objects in 2007A&A...466..589Q and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact