Fast-rotating nearby solar-type stars

Cutispoto, G.; Tagliaferri, G.; Medeiros, J. R. De; Pastori, L.; Pasquini, L.; Andersen, J.

doi:10.1051/0004-6361:20021562

Cited by 32 publications

(35 citation statements)

References 21 publications

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“…Neither of these algorithms shows a solution with a high power and the most likely periods differ when deleting 20% of data randomly. This suggests that apart from the brightness variation of HD 102077 due to stellar activity as has also been seen in the shorter period observations (Cutispoto 1990(Cutispoto , 1993(Cutispoto , 1998 no other signal can be detected in the H data.…”

Section: V-band Variabilitysupporting

confidence: 58%

“…The photometric determination of the metallicity content is not very accurate because of HD 102077s binarity and variability and this may be the cause of the discrepancy. For instance, Cutispoto (1990) measured the U BVRI colours over several photometric phases A&A 564, A10 (2014) and observed that U − B varies by 0.04 mag and that the star gets bluer at light maximum. Even stronger variations have been observed by Udalski & Geyer (1985).…”

Section: Introductionmentioning

confidence: 99%

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The young binary HD 102077: Orbit, spectral type, kinematics, and moving group membership

Wöllert

Brandner

Reffert³

et al. 2014

A&A

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The K-type binary star HD 102077 was proposed as a candidate member of the TW Hydrae association (TWA) which is a young (5−15 Myr) moving group in close proximity (∼50 pc) to the solar system. The aim of this work is to verify this hypothesis by different means. We first combine diffraction-limited observations from the ESO NTT 3.5 m telescope in SDSS-i and SDSS-z passbands (three epochs) and ESO 3.6 m telescope in H-band (one epoch) with literature data to obtain a new, amended orbit fit of the visual binary. We then estimate the spectral types of both components from the i − z colours and reanalyse the H parallax and proper motion taking the orbital motion into account. Moreover, we use two high-resolution spectra of HD 102077 obtained with the fibre-fed optical echelle spectrograph FEROS at the MPG/ESO 2.2 m telescope to determine the radial velocity and the lithium equivalent width (EW) of the system. Finally, we use all the information to discuss the kinematic properties of HD 102077 and to estimate the age of the system. The orbital elements of the HD 102077 trajectory are well constrained and we derive a total system mass of 2.6 ± 0.8 M and a semi-major axis of 14.9 ± 1.6 AU. From the i − z colours we infer an integrated spectral type of K2V, and individual spectral types of K0 ± 1 and K5 ± 1 for primary and secondary, respectively. The radial velocity corrected for the orbital motion of the system is 17.6 ± 2 km s −1 . Even though the parallax determination from the H data is not influenced by the orbital motion, the proper motion changes to µ α * cos δ = −137.84 ± 1.26 mas yr −1 and µ δ = −33.53 ± 1.45 mas yr −1 . With the resultant space motion, the probability of HD 102077 being a member of TWA is less than 1%. Furthermore, the lithium equivalent width of 200 ± 4 mÅ is consistent with an age between 30 Myr and 120 Myr and thus older than the predicted age of TWA. The comparison of HD 102077's temperature and luminosity to isochrones supports this result. In conclusion, HD 102077's age, galactic space motion, and position do not fit TWA or any other young moving group.

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Section: V-band Variabilitysupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

The young binary HD 102077: Orbit, spectral type, kinematics, and moving group membership

Wöllert

Brandner

Reffert³

et al. 2014

A&A

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“…Since a light curve represents one-dimensional time series the resulting stellar image contains information on the spot distribution only in one direction, in longitude, while spot extents and locations in latitude remain uncertain. However, because of the projection effect and limb darkening, light-curve inversion images show better-defined structures than the light curves themselves and, therefore, can be used to determine longitudes of spot Rucinski (1983) 3 4 44 982-44 993 74 Rucinski (1983) 4 3 45 249-45 266 180 Kubiak (1985) 3 45 791 43 Innis et al (1988) 3 9 46 019-46 020 18 Innis et al (1988) 3 9 46 040-46 050 745 Lloyd 46 043-46 055 614 Jetsu et al (1990) 3 4 46 096-46 097 40 Innis et al (1988) 3 9 46 389-46 397 23 Cutispoto & 3 5, 6 Rodonò (1988) 46 445-46 446 14 Innis et al (1988) 3 9 46 520-46 521 29 Innis et al (1988) 3 9 46 703-46 704 100 Innis et al (1988) 3 9 46 736-46 743 107 Kubiak et al (1995) 3 46 756-46 841 42 Cutispoto (1990) 3 5 46 810-46 811 64 Innis et al (1988) 3 9 47 548-47 595 60 Kürster et al (1994) Bos (1994b) 3 11 49 311-49 323 34 Unruh et al (1995) 5 2 49 317-49 327 20 Anders (1994) 3 9 49 659-49 724 708 Budding et al (1995) concentrations. Although this approach is less informative than the Doppler imaging technique, the analysis of long series of photometric observations allows us to recover longitudinal spot patterns and study their long-term evolution.…”

Section: Light Curve Inversionsmentioning

confidence: 99%

Magnetic activity in the young solar analog AB Dor

Järvinen

Berdyugina

Tuominen³

et al. 2005

A&A

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Abstract. We analyse photometric observations of the young active dwarf AB Dor, spanning more than 20 years. Similar to the young solar analog LQ Hya, AB Dor shows long-lived, nonaxisymmetric spot distribution -active longitudes in opposite hemispheres. The active longitudes migrate nonlinearly in the fixed reference frame, because of the differential rotation and changes of the mean spot latitudes. At least two activity cycles are found in the data. One cycle originates from repeating switches of the activity between the two active longitudes in about (2-3)-year intervals. This results in the flip-flop cycle of about 5.5 years, which includes two consecutive switches. The 5.5-yr cycle also modulates variations of the minimum stellar brightness and the peak-to-peak amplitude, that suggests a periodic redistribution of the spot area between the opposite longitudes and supports the reality of the flip-flop cycle. The other cycle is clearly seen in variations of the mean and maximum stellar brightness on the time-scale of 20 years and is reminiscent of the 11-year sunspot cycle.

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“…In the α Per cluster, more rapid rotators also appear to have a stronger lithium abundance (Balachandran et al 1988;Stauffer et al 1993). These results are the same for nearby field solar-type stars (de Medeiros et al 2000;do Nascimento et al 2000;Cutispoto et al 2003). On the other hand, observations and data analysis show that the rapid rotation of young solar-type stars exhibits higher X-ray luminosity Xing et al 2007a).…”

Section: Discussion and Resultsmentioning

confidence: 74%

Lithium abundances of nearby young solar-type stars based on optical high-resolution spectroscopy

Xing

2012

A&A

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Context. Lithium has long been recognized as a powerful tool for investigating the internal mixing of low-mass stars. In addition, accurate measurements of lithium abundances in young solar-type stars provide independent and reliable age diagnostics. Aims. To study the relationship between lithium and activity in normal solar type-type stars and determine the effectiveness of lithium and kinematics as activity indicators, we perform a lithium survey of nearby late-type stars. We search for nearby young solar-type stars and investigate the relationship between lithium abundances and X-ray activity by measuring log L x . Methods. On the basis of high-resolution spectroscopic observations, we derived the lithium abundances of 33 young solar-type stars by comparing the measured Li I λ 670.8 nm equivalent widths with the curve of growth calculations in non-LTE (NLTE) conditions. Results. We obtain the lithium abundances of a sample of young solar-type stars. Using the lithium abundance and X-ray luminosity, L x , we investigate the relationship between Li abundance and X-ray activity. We find a clear correlation between lithium abundance (log N(Li)) and X-ray luminosity, log L x , for our sample stars. Conclusions. As the X-ray luminosity, L x , becomes stronger, the lithium abundance decreases in our sample (11 pre-main-sequence, 15 zero-age-main-sequence, and 7 young main-sequence) stars. The results imply that there is a large number of solar-type stars. A correlation appears to exist between Li abundance and age, thus confirming the presence of very active young stars close to the Sun.

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Fast-rotating nearby solar-type stars

Cited by 32 publications

References 21 publications

The young binary HD 102077: Orbit, spectral type, kinematics, and moving group membership

The young binary HD 102077: Orbit, spectral type, kinematics, and moving group membership

Magnetic activity in the young solar analog AB Dor

Lithium abundances of nearby young solar-type stars based on optical high-resolution spectroscopy

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