2010A&A...511L...7M


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.12CEST02:04:21

2010A&A...511L...7M - Astronomy and Astrophysics, volume 511, L7-7 (2010/2-2)

HR 7355 - another rapidly braking He-strong CP star?

MIKULASEK Z., KRTICKA J., HENRY G.W., DE VILLIERS S.N., PAUNZEN E. and ZEJDA M.

Abstract (from CDS):

Strong meridional mixing induced by rapid rotation is one reason why all hot main-sequence stars are not chemically peculiar. However, the finding that the He-strong CP star HR 7355 is a rapid rotator complicates this concept. Our goal is to explain the observed behaviour of HR 7355 based on period analysis of all available photometry.Over two years, we acquired 114 new BV observations of HR7355 at observatories in Arizona, U.S.A and Cape Town, South Africa. We performed period analyses of the new observations along with new analyses of 732 archival measurements from the Hipparcos and ASAS projects. We find that the light curves of HR7355 in various filters are quite similar, with amplitudes 0.035(4), 0.036(4), and 0.038(3)mag in B, Hp, and V, respectively. The light curves are double-peaked, with unevenly deep minima. We substantially refine the rotational period to be P=0.5214410(4)d, indicating that HR7355 is the most rapidly rotating CP star known. Our period analyses reveal a possible lengthening of the rotational period with {dot}(P)/P=2.4(8)x10–6/yr. We conclude that the shape and amplitude of HR7355 light curves are typical of magnetic He-strong CP stars, for which light variations are the result of photospheric spots on the surface of a rotating star. We hypothesise that the light variations are caused mainly by an uneven distribution of overabundant helium on the star's surface. We briefly describe and discuss the cause of the rapid rotational braking of the star.

Abstract Copyright:

Journal keyword(s): stars: chemically peculiar - stars: variables: general - stars: individual: HR7355 - stars: rotation

VizieR on-line data: <Available at CDS (J/A+A/511/L7): bvphot.dat>

Simbad objects: 9

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Number of rows : 9

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* V901 Ori Ro* 05 40 56.3704270929 -01 30 25.856714776 5.96 6.82 6.96     B2V 304 2
2 V* V407 Car a2* 10 38 17.5536103438 -65 02 30.964793188   6.646 6.711     B9Vn 80 0
3 V* CU Vir a2* 14 12 15.8054758 +02 24 33.953395 4.46 4.90 5.02 5.10 5.23 ApSi 359 0
4 V* V771 Her a2* 17 58 52.3061764690 +45 28 34.388554506   6.407 6.481     B9pSiSr 84 0
5 V* EE Dra a2* 18 58 52.6265049377 +69 31 52.643645693   6.353 6.506     B9III 88 1
6 HD 179520 PM* 19 13 56.3548092792 -26 52 34.523896999   7.46 7.10     F3V 23 0
7 HD 181240 ** 19 20 38.1479027497 -22 24 09.165713438   5.851 5.579     A8III 35 0
8 HD 182180 * 19 24 30.1796083175 -27 51 57.396699026 5.22 5.889 6.011     B2Vnn 97 0
9 HD 182896 Er* 19 25 18.1494374784 +37 14 42.716385466   7.93 6.80     K0 14 0

    Equat.    Gal    SGal    Ecl

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2021.05.12-02:04:21

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