C. Chavarría-K2, M. A. Moreno-Corral2, L. Terranegra3 and E. de Lara2
2 Instituto de Astronomía, UNAM/Campus Ensenada, P.O. Box 439027, San Diego, CA 92143-9027, USA (chavarri@astrosen.unam.mx, mam@astrosen.unam.mx).
3 Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli, Italia.
Received, 2004 August 19
Accepted 2005 January 7
RESUMEN
Presentamos observaciones espectroscópicas (resolución ≥ 1750 en λ = 6708 Å) y fotométricas (ubvy-β) recientes de la singular estrella T Tauri con líneas en emisión débiles HBC 498 (= DL Ori/G1), aún asociada a su nube de polvo progenitora, y de otras cuatro estrellas vecinas y brillantes, todas ellas con nebulosidades de reflexión asociadas, las cuales conforman un trapecio estrecho en L1641 en la constelación de Orión. Dos estrellas resultan ser del tipo T Tauri "clásicas" y dos del tipo T Tauri "con líneas en emisión débiles". La mayoría presentan la huella de juventud del Li I en su espectro. De los datos y su comparación con modelos evolutivos de estrellas pre-secuencia principal, encontramos que son coetáneas, con masas alrededor de 1 M๏ y edades del orden del tiempo de contracción gravitacional o menor (≈ 1 — 5 x 105 años). Finalmente, discutimos brevemente el estado evolutivo de estos objetos y sus repercusiones.
ABSTRACT
We present recent spectroscopic (resolution ≥ 1750 at λ = 6708 Å) and photometric (ubvy-β) observations of the singular weak-line T Tauri star HBC 498 (= DL Ori/G1) still associated with its parental dust cloud and of at least four other bright neighboring stars associated with reflection nebulosities that together form a tight trapezium in L1641 in Orion. Most of them have the youth signature of Li I in their spectra. We find that two of the objects are "classic" T Tauri and another two are "weak-line" T Tauri stars. From the data and their comparison with models of pre-main sequence stellar evolution we find that they are coeval, and that they have masses of the order of 1 M๏ and ages of the order of their gravitational contraction times or less (≈1 — 5 x 105 yr). Finally, we briefly discuss their evolutionary state and its repercussions.
Key Words: Stars: Abundances — Stars: Emission line — Stars: Individual (HBC 498) — Stars: Pre-main sequence.
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]]> ACKNOWLEDGMENTS
This work was partially supported by Consejo Nacional de Ciencia y Tecnología, México (projects 400340-4-2243-PE and 400354-5-27757 E) and by CNR-GNA98 and COFIN98-MURST of Italy.
REFERENCES
Alcalá, J. M., Covino E., Torres, G., et al. 2000, A&A, 353, 186 [ Links ]
Alcalá, J. M., Terranegra L., Wichmann, R., et al. 1996, A&AS, 119, 7 (A96) [ Links ]
Baraffe, I., Chabrier, G., Allard, F., & Hauschildt, P. H. 1998, A&A, 337, 403 [ Links ]
Bernes, C. 1977, A&AS, 29, 65 [ Links ]
Bertout, C., Robichon, N., & Arenou, F. 1999, A&A. 352, 574 [ Links ]
Carballo, R., Eiroa, C., & Mampaso A. 1988, MNRAS. 232, 497 (CEM88) [ Links ]
Charbonnel, C., Doppen, W., Schaerer, D., et al. 1999, A&AS, 135, 405 [ Links ]
Chavarría-K, C. 1981, A&A, 101,105 [ Links ]
Chavarría, A., de Lara, E., & Chavarría-K, C. 2000, ArcoIris.v02 (RainBow.v02), A Multiwavelength Reduction Program for IBM Compatible PC's, Instituto de Astronomía-UNAM, P.O.Box 439027, San Diego CA 92143-9027, USA [ Links ]
Chavarría-K, C., Moreno-Corral, M. A., & de Lara, E. 1995, in RevMexAA(SC) 3, The Fifth Mexico- Texas Conference on Astrophysics: Gaseous Nebulae and Star Formation, eds. M. Peña & S. Kurtz (Tequesquitengo, Mor., Mexico: Inst. Astron., UNAM), 117 [ Links ]
Chavarría-K, C., Terranegra, L., Moreno-Corral, M. A., & de Lara, E. 2005, in preparation [ Links ]
Cohen, M. 1980, AJ, 85, 29 [ Links ]
Cohen, M., & Kuhi, L.V. 1979, ApJS, 41, 743 [ Links ]
D'Antona, F., & Mazzitelli, I. 1994, ApJS, 90, 467 [ Links ]
----------. 1997, in Cool Stars in Clusters and the Sun, eds. R. Palavicini & G. Micela, Mem. Soc. Astron. Ital., 68, 807 [ Links ]
Dorchner, J., & Gürtler, J. 1963, AN, 287, 257 [ Links ]
Gyulbudaghian, A. L., Glushov, Y. I., & Denisyuk, E. K. 1978, ApJ, 224, L137 [ Links ]
Hartigan P., Strom, K. M., & Strom, S. E. 1994, ApJ, 427, 961 [ Links ]
Herbig, G. H. 1962, Advances in Astronomy & Astrophysics, 1, 47, [ Links ]
Herbig, G. H., & Bell, K. R. 1988, Lick Observatory Bulletin Nr., 1111, [ Links ]
Iben I. 1965, ApJ, 141, 993 [ Links ]
Jacoby, G. H., Hunter, D. A., & Christian, C. A. 1984, ApJS, 56, 257 [ Links ]
Koornneef, J. 1983, A&A, 128, 84 [ Links ]
Mathis, J. S. 1990, ARA&A, 28, 37 [ Links ]
Mitchell, R. I. 1960, ApJ, 132, 68 [ Links ]
Neuhüauser, R., & Brandner, W. 1998, A&A, 330, L29 [ Links ]
Nissen, P. E. 1984, User's Manual of the Danish Photometer, Instituto de Astronomía-UNAM (México), P.O.Box 439027, San Diego CA 92143-9027, USA [ Links ]
Olsen, E. H. 1984, A&AS, 57, 443 [ Links ]
Palla, F. & Stahler, S. W. 1993, ApJ, 418, 414 [ Links ]
Rodríguez, L. F., Moran, J. M., Ho, P. T. P., & Gottlieb, E.W. 1980, ApJ, 235, 845 [ Links ]
Shu, F. H., Adams, F. C., & Lizano, S. 1987, ARA&A, 25, 23 [ Links ]
Siess, L., Dufour, E., & Forestini, M. 2000, A&A, 358, 593 [ Links ]
Terranegra, L., Chavarríía-K, C., Díaz, S., & González-Patiño, D. 1994, A&AS, 104, 557 [ Links ]
Tout, C. A., Livio, M., & Bonnell, I. A. 1999, MNRAS. 310, 360 [ Links ]
van den Bergh, S. 1966, AJ, 71, 990 [ Links ]
Zinnecker, H., McCaughrean, M. J., & Wilking, B. A. 1993, Protostars and Planets III, eds. E. H. Levy & J. I. Lunine (Tucson, AZ: The University of Arizona Press), p. 429 [ Links ]
1 Based on observations collected at the Observatorio Astronómico Nacional in San Pedro Mártir, B. C., México, operated by the Instituto de Astronomía of the Universidad Nacional Autónoma de México.
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