ACCRETION AND OUTFLOW IN THE PROPLYD-LIKE OBJECTS NEAR CYGNUS OB2

被引:11
作者
Guarcello, M. G. [1 ,2 ]
Drake, J. J. [2 ]
Wright, N. J. [2 ,3 ]
Garcia-Alvarez, D. [4 ,5 ,6 ]
Kraemer, K. E. [7 ]
机构
[1] INAF Osservatorio Astron Palermo, I-90134 Palermo, Italy
[2] Smithsonian Astrophys Observ, Cambridge, MA 02138 USA
[3] Univ Hertfordshire, CAR STRI, Hatfield AL10 9AB, Herts, England
[4] Univ La Laguna, Dept Astrofis, D-38206 San Cristobal la Laguna, Tenerife, Spain
[5] Grantecan CALP, E-38712 Brena Baja, La Palma, Spain
[6] Inst Astrofis Canarias, E-38205 San Cristobal la Laguna, Tenerife, Spain
[7] Boston Coll, Inst Sci Res, Newton, MA 02459 USA
基金
美国国家科学基金会;
关键词
stars: formation; stars: mass-loss; stars: pre-main sequence; stars: protostars; T-TAURI STARS; HUBBLE-SPACE-TELESCOPE; PHOTOEVAPORATING CIRCUMSTELLAR DISKS; FORBIDDEN-LINE EMISSION; YOUNG STELLAR OBJECTS; ORION NEBULA; MASSIVE STARS; MAGNETOSPHERIC ACCRETION; SPECTROSCOPIC EVIDENCE; ULTRAVIOLET-RADIATION;
D O I
10.1088/0004-637X/793/1/56
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Cygnus OB2 is the most massive association within 2 kpc from the Sun, hosting hundreds of massive stars, thousands of young low mass members, and some sights of active star formation in the surrounding cloud. Recently, 10 photoevaporating proplyd-like objects with tadpole-shaped morphology were discovered in the outskirts of the OB association, approximately 6-14 pc away from its center. The classification of these objects is ambiguous, being either evaporating residuals of the parental cloud that are hosting a protostar inside or disk-bearing stars with an evaporating disk, such as the evaporating proplyds observed in the Trapezium Cluster in Orion. In this paper, we present a study based on low-resolution optical spectroscopic observations made with the Optical System for Imaging and low Resolution Integrated Spectroscopy, mounted on the 10.4 m Gran Telescopio CANARIAS, of two of these protostars. The spectrum of one of the objects shows evidence of accretion but not of outflows. In the latter object, the spectra show several emission lines indicating the presence of an actively accreting disk with outflow. We present estimates of the mass loss rate and the accretion rate from the disk, showing that the former exceeds the latter as observed in other known objects with evaporating disks. We also show evidence of a strong variability in the integrated flux observed in these objects as well as in the accretion and outflow diagnostics.
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页数:14
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