Forbidden line emission and correlations with the infra-red excess in Herbig Ae/Be stars
In a sample of 22 Herbig Ae/Be stars, covering a range of equivalent widths in Hα from 10 to 125 Å, we find a correlation between the [OI]λ6300 and Hα line luminosities and the excess mid-IR luminosity (L MIR) between 0.6μm and 10.2μm over three orders of magnitude. This matches the trend seen in T-Tauri stars (Cabrit et al. (1990)) and extends the range of these correlations to over five orders in magnitude in L MIR and over a mass range of 0.4 to 25 M ⊙
We argue that such correlations observed in both Herbig Ae/Be and T-Tauri stars arise from a proportionality between the mass accretion and mass-loss processes occurring in and about these young stars. Statistical tests indicate that the [OI] line luminosities correlate better with L MIR than with L *, the underlying stellar luminosity. However the Hα line luminosity correlates equally well with L MIR or L *. This suggests that, at least in part, the Hα line arises from a different source than the [OI] line. The smooth rise in [OI] line luminosity with L MIR, from T-Tauri stars to the much more luminous Herbig Ae/Be stars, implies that the same physical process is responsible of the forbidden line emission in all these stars. This is in conflict with recent models (Böhm and Catala (1994)) which propose that the forbidden line luminosity in Herbig Ae/Be stars is not disk related as in the T-Tauri stars.
KeywordsStellar Wind Circumstellar Disk Disk Activity Smooth Rise Line Luminosity
Unable to display preview. Download preview PDF.
- Corcoran, M. and Ray, T. 1994 Proceedings of the First Conference on the Nature and Evolutionary Status of Herbig Ae/Be Stars, P. S. Thé, Pérez, M. R., and E. P. J., van den Heuvel, Astronomical Society of the Pacific Conference Series, p. 151.Google Scholar
- Isobe, T., LaValley, M. and Feigelson, E. D. 1992, ASURV software supplied with STSDAS/IRAF.Google Scholar
- Mundt, R., and Ray, T. P., 1994, Proceedings of the First Conference on the Nature and Evolutionary Status of Herbig Ae/Be Stars, P. S. Thé, Pérez, M. R., and E. P. J., van den Heuvel, Astronomical Society of the Pacific Conference Series, p. 237.Google Scholar
- Staude, H.J., Elsässer, H. 1993, Ann. Rev A&A, 5, 165.Google Scholar