OO Serpentis, an Intermediate Object between FUors and EXors?
L'éclat de OO Serpentis, une étoile jeune enfouie, a augmenté de 5 magnitudes entre 1994 et 1995, puis a graduellement diminué. Un suivi avec ISO, complété par des observations en 2004 montre que OO Ser, revenu rapidement à l'état quiescent serait intermédiaire entre les FUors et EXors.
OO Serpentis is a deeply embedded young star which brightened by 5 mag in Kband between 1994 and 1995, and gradually faded afterwards. In many respects the star and its outburst is very similar to the well-known young eruptive stars (FUors and EXors). We monitored the eruption of OO Ser for 20 months with the Infrared Space Observatory in the 3.6 100 µm wavelength range. We complemented this dataset with new (ground-based and spaceborn) infrared observations from 2004 and constructed the light curve of the outburst at 10 different wavelengths. Our results show that by 2004 OO Ser already returned to the pre-outburst state at 2.2 µm, suggesing a significantly shorter outburst timescale than that of classical FUors, but longer than that of EXors. This may indicate that OO Ser together with the recently erupted star V1647 Ori is the first example of an intermediate object between FUors and EXors.
Ágnes KÓSPÁL, Péter ÁBRAHÁM, Timo PRUSTI, José ACOSTA-PULIDO
étoiles pre-séquence principale, individuelle OO Ser, infrarouge étoiles.
stars pre-main sequence, individual OO Ser, infrared stars.