2008A&A...480..481B


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.02CET12:18:32

2008A&A...480..481B - Astronomy and Astrophysics, volume 480, 481-487 (2008/3-3)

Cyclical period changes in HT Cassiopeiae: a difference between systems above and below the period gap.

BORGES B.W., BAPTISTA R., PAPADIMITRIOU C. and GIANNAKIS O.

Abstract (from CDS):

We report identification of cyclical changes in the orbital period of the eclipsing cataclysmic variable HT Cas. We measured new white-dwarf mid-eclipse timings and combined them with published measurements to construct an observed-minus-calculated diagram covering 29 years of observations. The data present a 36 yr period modulation of semi-amplitude ∼40s, with a statistical significance greater than 99.9 percent with respect to a constant period. We combine our results with those in the literature to revisit the issue of cyclical period changes in cataclysmic variables and their interpretation in terms of a solar-type magnetic activity cycle in the secondary star. A diagram of fractional period change (Δ P/P) versus the angular velocity of the active star (Ω) for cataclysmic variables, RS CVn, W UMa, and Algols, reveal that close binaries with periods above the gap (secondaries with convective envelopes) satisfy a relationship ΔP/P∝Ω–0.7±0.1. Cataclysmic variables below the period gap (with fully convective secondaries) deviate from this relationship by more than 3-σ, with average fractional period changes ≃6 times smaller than those of the systems above the gap.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - stars: dwarf novae - stars: evolution - stars: binaries: eclipsing - stars: individual: HT Cas

Simbad objects: 15

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Number of rows : 15

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 V* HT Cas DN* 01 10 13.1213309510 +60 04 35.489284826           M5.5e 368 0
2 V* RW Tri NL* 02 25 36.1555561414 +28 05 50.893091344   13.50 12.50     M0V 289 0
3 V* T Aur No* 05 31 59.1179548200 +30 26 45.033734428 4.80 4.49 4.10     ~ 257 1
4 V* U Gem DN* 07 55 05.2323858391 +22 00 05.045435077   15.3 14.54     DA 1049 0
5 V* Z Cha DN* 08 07 27.7421647579 -76 32 00.679589237   12.00       M5.5 589 1
6 V* AC Cnc EB* 08 44 27.1122164614 +12 52 31.996499274   13.80 14.15     K1-3V 124 0
7 V* OY Car DN* 10 06 22.0792108747 -70 14 04.582997921           ~ 549 0
8 V* EX Hya DN* 12 52 24.2220533405 -29 14 56.001981146   13.51 13.49 13.55   M5-6V 652 0
9 V* UX UMa NL* 13 36 40.9533414077 +51 54 49.424110262   12.78 13.26     Oev: 502 0
10 V* V2051 Oph DN* 17 08 19.0875545832 -25 48 31.695764973   17.5       ~ 228 0
11 V* EX Dra DN* 18 04 14.2486747659 +67 54 12.271788519   14.5 14.7     ~ 113 0
12 V* DQ Her No* 18 07 30.2510755201 +45 51 32.564649735   12.99 15.16 11.46   M3+Ve 966 1
13 V* V4140 Sgr DN* 19 58 49.7022483148 -38 56 13.225654759           ~ 59 0
14 V* FO Aqr DQ* 22 17 55.3796324299 -08 21 03.755362145           ~ 326 0
15 V* IP Peg DN* 23 23 08.5362716048 +18 24 59.206210572           M2 361 0

    Equat.    Gal    SGal    Ecl

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2020.12.02-12:18:32

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