Photometry and Spectroscopy of 11 γ Doradus Stars

Henry, Gregory W.; Fekel, Francis C.; Henry, Stephen M.

doi:10.1086/511820

Cited by 38 publications

(46 citation statements)

References 61 publications

(99 reference statements)

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“…Their periods range from 0.3 to 1.7 d, though two cases are known at longer periods, up to 2.7 d (Henry et al 2007(Henry et al , 2011. Our periods are compatible with this range.…”

Section: Group 4 Of Periodic Variables: γ Dor Candidatessupporting

confidence: 78%

Stellar variability in open clusters

Mowlavï¹,

Barblan²,

Saesen³

et al. 2013

A&A

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Aims. We analyze the population of periodic variable stars in the open cluster NGC 3766 based on a 7-year multiband monitoring campaign conducted on the 1.2 m Swiss Euler telescope at La Silla, Chili. Methods. The data reduction, light curve cleaning, and period search procedures, combined with the long observation time line, allowed us to detect variability amplitudes down to the millimagnitude (mmag) level. The variability properties were complemented with the positions in the color-magnitude and color-color diagrams to classify periodic variable stars into distinct variability types. Results. We find a large population (36 stars) of new variable stars between the red edge of slowly pulsating B (SPB) stars and the blue edge of δ Sct stars, a region in the Hertzsprung-Russell (HR) diagram where no pulsation is predicted to occur based on standard stellar models. The bulk of their periods ranges from 0.1 to 0.7 d, with amplitudes between 1 and 4 mmag for the majority of them. About 20% of stars in that region of the HR diagram are found to be variable, but the number of members of this new group is expected to be higher, with amplitudes below our mmag detection limit. The properties of this new group of variable stars are summarized and arguments set forth in favor of a pulsation origin of the variability, with g-modes sustained by stellar rotation. Potential members of this new class of low-amplitude periodic (most probably pulsating) A and late-B variables in the literature are discussed. We additionally identify 16 eclipsing binary, 13 SPB, 14 δ Sct, and 12 γ Dor candidates, as well as 72 fainter periodic variables. All are new discoveries. Conclusions. We encourage searching for this new class of variables in other young open clusters, especially in those hosting a rich population of Be stars.

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“…Their periods range from 0.3 to 1.7 d, though two cases are known at longer periods, up to 2.7 d (Henry et al 2007(Henry et al , 2011. Our periods are compatible with this range.…”

Section: Group 4 Of Periodic Variables: γ Dor Candidatessupporting

confidence: 78%

Stellar variability in open clusters

Mowlavï¹,

Barblan²,

Saesen³

et al. 2013

A&A

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“…Before the CoRoT and Kepler space missions sixty-six γ Dor variables were known, according to Henry et al (2007), and about 50% of them were found in binary stars (12 visual binaries, 10 double-lined, and 6 single-lined spectroscopic binaries, no EB). The first γ Dor in an eclipsing binary (VZ CVn) was announced by Ibanoǧlu et al (2007) but the quality and the coverage of their ground-based photometry was insufficient for a detailed asteroseismic study.…”

Section: Introductionmentioning

confidence: 99%

CoRoT 102918586: aγDoradus pulsator in a short-period eccentric eclipsing binary

Maceroni

Montalbán

Gandolfi

et al. 2013

A&A

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Pulsating stars in eclipsing binary systems are powerful tools to test stellar models. Binarity enables us to constrain the pulsating component's physical parameters and this knowledge drastically improves the input physics for asteroseismic studies. The study of stellar oscillations then allows us to improve our understanding of stellar interiors and stellar evolution. The space mission CoRoT discovered several promising objects suitable for these studies. They were photometrically observed with unprecedented accuracy, but needed spectroscopic follow-up. A promising target was the relatively bright eclipsing system CoRoT 102918586, which turned out to be a double-lined spectroscopic binary and also showed clear evidence of γ Dor type pulsations. With the aim of combining the information from binarity and pulsation and fully exploiting the potential of CoRoT photometry we obtained phase resolved high-resolution spectroscopy with the Sandiford spectrograph at the McDonald 2.1m telescope and the FEROS spectrograph at the ESO 2.2 m telescope. Spectroscopy yielded both the radial velocity curves and, after spectra disentangling, the component effective temperatures, metallicity, and line-of-sight projected rotational velocities. The CoRoT light curve was analyzed with an iterative procedure, devised to disentangle eclipses from pulsations. The eclipsing binary light curve analysis, combined with the spectroscopic results, provided an accurate determination of the system parameters, and the comparison with evolutionary models provided strict constraints on the system age. Finally, the residuals obtained after subtraction of the best-fitting eclipsing binary model were analyzed to determine the pulsator properties. We achieved a complete and consistent description of the system. The primary star pulsates with typical γ Dor frequencies and shows a splitting in period that is consistent with high order g-mode pulsations in a star of the corresponding physical parameters. The value of the splitting, in particular, is consistent with pulsations in = 1 modes.

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“…Pulsation periods have previously been determined from photoelectric photometry for HD6568 (Henry et al 2011), HD17310 (Henry et al 2005), HD19684 (Henry & Fekel 2002), and HD62196 (Henry et al 2011). The ongoing analysis of our unpublished photometry of HD776, done in a manner similar to that outlined in the above papers, produces pulsation periods of 0.19968 and 0.19389 days.…”

Section: Pulsation Period Analysismentioning

confidence: 98%

The SPECTROSCOPIC ORBITS OF FIVE Γ DORADUS STARS

Fekel

Henry

Pourbaix

2016

Self Cite

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We have determined the spectroscopic orbits of five γDor variables, HD776, HD 6568, HD17310, HD19684, and HD62196. Their orbital periods range from 27.8 to 1163 days and their eccentricities from 0.01 to 0.65. Of the five systems, only HD19684 shows lines of its binary companion, but those lines are always so weak and blended with the lines of the primary that we were unable to measure them satisfactorily. The velocity residuals of the orbital fits were searched for periodicities associated with pulsation. No clear, convincing case for velocity periodicities in the residuals was found in four of the five stars. However, for HD17310 we identified a period of 2.13434 days, a value in agreement with the largest amplitude period previously found photometrically for that star. The velocity residuals of HD62196 have a long-term trend suggesting that it is a triple system.

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Photometry and Spectroscopy of 11 γ Doradus Stars

Cited by 38 publications

References 61 publications

Stellar variability in open clusters

Stellar variability in open clusters

CoRoT 102918586: aγDoradus pulsator in a short-period eccentric eclipsing binary

The SPECTROSCOPIC ORBITS OF FIVE Γ DORADUS STARS

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