Evidence for starspots on DK Draconis /HR 4665/

Guinan, E. F.; McCook, G. P.; Fragola, J. L.; Odonnell, W. C.; Tomczyk, S.; Weisenberger, A.G.

doi:10.1086/113170

Cited by 8 publications

(6 citation statements)

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“…Guinan et al (1982) confirmed that the star varied on a time scale of several days with a full amplitude of about 0. m 1. They could not exclude that the variations were in fact periodic, with a possible period of about 2 days or shorter.…”

Section: Hd 201733 (Mwc 363)mentioning

confidence: 57%

UBV photometry of Be stars at Hvar: 1972–1990

Pavlovski¹,

Harmanec

Božić³

et al. 1997

Astron. Astrophys. Suppl. Ser.

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Abstract. A summary of results of the systematic UBV photoelectric monitoring of bright northern Be stars carried out at the Hvar Observatory between 1972 and 1990 is presented. Altogether, 76 Be stars of all luminosity classes were observed and 13 848 UBV measurements secured. Simultaneously, 9 648 UBV measurements of 48 check stars (most of them of early spectral types) were obtained. A careful transformation of all observations into the standard Johnson system allowed detection and monitoring of even very mild long-term light and colour variations of these objects. Almost all early-type Be stars in the sample turned out to be variable. For several stars phase-locked light variations related to their binary nature were established. Sudden brightenings, on a time scale of a few days, were detected for o Cas and QR Vul.

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Section: Hd 201733 (Mwc 363)mentioning

confidence: 57%

UBV photometry of Be stars at Hvar: 1972–1990

Pavlovski¹,

Harmanec

Božić³

et al. 1997

Astron. Astrophys. Suppl. Ser.

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“…In eight months in 1978 the amplitude of the light variation grew from only 0.08 mag in V (Chambliss et al 1978) to 0.2 mag (Sarma and Ausekar 1980). Strong radio outbursts (Feldman et al 1978;Feldman, MacLeod, and Andrew 1979) were detected during this time, and Guinan et al (1979) reported the observation of a long-lasting flarelike event in optical photometry. This sudden impulse of activity, and the development of a large photometric amplitude, argue very strongly that a new complex of activity emerged during this time near the equator of HR 1099, composed not of 20 active regions but of 20,000, if the scale of individual active regions on HR 1099 is similar to those of the sun.…”

Section: Discussionmentioning

confidence: 87%

Doppler Imaging of spotted stars - Application to the RS Canum Venaticorum star HR 1099

Vogt¹,

Penrod²

1983

PASP

302

168

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We discuss a technique for imaging the surfaces of certain rapidly rotating spotted stars. The method exploits the correspondence between wavelength position across a rotationally broadened spectral line and spatial position across the stellar disk. Preliminary Doppler Images of the RS CVn star HR 1099 show spots which exhibit a striking similarity in shape and location to X-ray images of solar coronal holes. We suggest that the large star spots on RS CVn's and other active latetype stars emerge at low latitude as scaled-up stellar analogs of solar complexes, but as they migrate poleward, they more closely resemble photospheric analogs of solar coronal holes. The evolution of starspots appears remarkably similar to that of large-scale magnetic fields of the sun.

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“….a region of tremendous sunspot activity darkens one side of the cool star", assuming synchronous rotation, can reproduce the many photometric complications observed in RS CVn. Recent studies of starspots and rotations of the components of RS CVn systems include those by Ramsey andNations (1980), Vogt (1981), Guinan et al (1982), andFekel (1983), plus the references therein.…”

Section: Rs Cvn Binaries and Fk Com Stars Rs Cvn Binaries Have Been mentioning

confidence: 99%