Classification of a selected sample of weak T Tauri stars

Gregorio-Hetem, J.; Hetem, A.

doi:10.1046/j.1365-8711.2002.05716.x

Cited by 56 publications

(44 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2, we compare our measurement of the Li EWs with those obtained by other authors for the same stars (Christian & Mathioudakis 2002;Wichmann et al 2000;Gregorio-Hetem & Hetem 2002;de Laverny et al 2003;Takeda & Kawanomoto 2005;Jasniewicz et al 1999;Montes et al 2001). The agreement between the values was good; however, for small EWs, we noted some differences between the samples of other authors and our results.…”

Section: Introductionsupporting

confidence: 79%

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

Xing

2012

A&A

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionsupporting

confidence: 79%

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

Xing

2012

A&A

View full text Add to dashboard Cite

show abstract

“…However, we do not see any significant flux excess in our stars except for the Herbig Ae/Be star SO230838 (HD 290772;Gregorio-Hetem & Hetem 2002). It is an intense accretor, IRAS source, X-ray emitter, F6-type star much warmer than tabulated in Table 2.…”

Section: Effective Temperaturesmentioning

confidence: 44%

Chemical abundances of late-type pre-main sequence stars in the σ Orionis cluster

Hernández¹,

Caballero

Rebolo

et al. 2008

A&A

View full text Add to dashboard Cite

Context. The young σ Orionis cluster is an important location for studying the formation and evolution of stars, brown dwarfs, and planetary-mass objects. Its metallicity, although it is a fundamental parameter, has not been well determined yet. Aims. We present the first determination of the metallicity of nine young late-type stars in σ Orionis. Methods. Using the optical and near-infrared broadband photometry available in the literature we derive the effective temperatures for these nine cluster stars, which lie in the interval 4300-6500 K (1-3 M ). These parameters are employed to compute a grid of synthetic spectra based on the code MOOG and Kurucz model atmospheres. We employ a χ 2 -minimization procedure to derive the stellar surface gravity and atmospheric abundances of Al, Ca, Si, Fe, Ni and Li, using multi-object optical spectroscopy taken with WYFFOS+AF2 at the William Herschel Telescope (λ/δλ ∼ 7500). Results. The average metallicity of the σ Orionis cluster is [Fe/H] = −0.02 ± 0.09 ± 0.13 (random and systematic errors). The abundances of the other elements, except lithium, seem to be consistent with solar values. Lithium abundances are in agreement with the "cosmic" 7 Li abundance, except for two stars which show a log (Li) in the range 3.6-3.7 (although almost consistent within the error bars). There are also other two stars with log (Li) ∼ 2.75. We derived an average radial velocity of the σ Orionis cluster of 28 ± 4 km s −1 . Conclusions. The σ Orionis metallicity is roughly solar.

show abstract

“…It was first listed in the Hα-emission star catalogues of MacConnell (1982) and Stephenson (1986) and followed-up afterwards by Downes & Keyes (1988), Torres et al (1995), Gregorio-Hetem & Hetem (2002), and Maheswar et al (2003). StHa 40 is a T Tauri star with variable spectral type (from F8, through G2 and G5, to K0), variable Hα emission (from pEW(Hα) = -14.5Å to a faint absorption), lithium absorption (from pEW(Li I) = +0.13 to +0.33Å), and radial velocity (indicative of possible spectral binarity).…”

Section: Stha 40 (No 78)mentioning

confidence: 99%

Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

2010

View full text Add to dashboard Cite

We look for high-amplitude variable young stars in the open clusters and associations of the Orion Belt. We use public data from the ASAS-3 Photometric V -band Catalogue of the All Sky Automated Survey, infrared photometry from the 2MASS and IRAS catalogues, proper motions, and the Aladin sky atlas to obtain a list of the most variable stars in a survey area of side 5 deg centred on the bright star Alnilam (ǫ Ori) in the centre of the Orion Belt. We identify 32 highly-variable stars, of which 16 had not been reported to vary before. They are mostly variable young stars and candidates (16) and background giants (8), but there are also field cataclysmic variables, contact binaries, and eclipsing binary candidates. Of the young stars, which typically are active Herbig Ae/Be and T Tauri stars with Hα emission and infrared flux excess, we discover four new variables and confirm the variability status of another two. Some of them belong to the well known σ Orionis cluster. Besides, six of the eight giants are new variables, and three are new periodic variables.

show abstract

Classification of a selected sample of weak T Tauri stars

Cited by 56 publications

References 33 publications

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

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

Chemical abundances of late-type pre-main sequence stars in the σ Orionis cluster

Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

Contact Info

Product

Resources

About