ATCA and Spitzer Observations of the Binary Protostellar Systems CG30 and BHR71

Xuepeng Chen; Ralf Launhardt; Tyler L. Bourke; Thomas Henning; Peter J. Barnes

doi:10.1086/589939

paper

ATCA and Spitzer Observations of the Binary Protostellar Systems CG30 and BHR71

arXiv:0805.1533 · doi:10.1086/589939

Abstract

We present interferometric observations with resolution of ~3 arcsecs of the isolated, low-mass protostellar double cores CG30 and BHR71 in the N2 $H + (1 - 0) l in e an d a t 3 mm d u s t co n t in uu m, u s in g t h e A u s t r a l ian T e l esco p e C o m p a c t A r r a y (A T C A) . T h er es u l t s a r eco m pl e m e n t e d b y in f r a r e dd a t a f r o m t h e S p i t z er S p a ce T e l esco p e . I n C G 30, t h e 3 mm d u s t co n t in uu mima g esr eso l v e tw oco m p a c t so u r ces w i t ha se p a r a t i o n o f 21.7 a r csecs (8700 A U) . I n B H R 71, s t r o n g d u s t co n t in uu m e mi ss i o ni s d e t ec t e d a tt h e p os i t i o n o f t h e mi d - in f r a r e d so u r ce I R S 1, w hi l eo n l y w e ak e mi ss i o ni s d e t ec t e df r o m t h eseco n d a r y mi d - in f r a r e d so u r ce I R S 2. A ss u min g o pt i c a l l y t hin 3 mm d u s t co n t in uu m e mi ss i o n, w e d er i v e h y d r o g e n g a s ma sseso f 0.05 - - 2.1$ M_\odot $f or t h e f o u r s u b - cor es . N 2 H + (1 - 0) l in ee mi ss i o ni s d e t ec t e d inb o t h C G 30 an d B H R 71, an d i ss p a t ia l l y a ssoc ia t e d w i t h t h e t h er ma l d u s t co n t in uu m e mi ss i o n . W e d er i v e t h e v e l oc i t y f i e l d s an df in d sy mm e t r i c v e l oc i t y g r a d i e n t s inb o t h so u r ces . A ss u min g t ha tt h ese g r a d i e n t s a r e d u e t ocor er o t a t i o n, w ees t ima t e t h es p ec i f i c an g u l a r m o m e n t aan d r a t i oso f r o t a t i o na l e n er g y t o g r a v i t a t i o na l e n er g y f or a l l cor es . W e a l so f in d t ha tt h e N 2 H + e mi ss i o ni ss t r o n g l y a f f ec t e d b y t h eo u t f l o w s, b o t hin t er m so f e n t r ainm e n t an d m o l ec u l e d es t r u c t i o n .$ Spitzer $ima g ess h o w t h e mi d - in f r a r e d e mi ss i o n f r o ma l l f o u r s u b - cor es . A l l f o u r so u r ces a pp e a r t o d r i v e t h e i r o w n o u t f l o w s . B a se d o n t h e A T C A an d$ Spitzer$ observations, we construct spectral energy distributions (SEDs) and derive temperatures and luminosities for all cores. Based on the morphology and velocity structure, we suggest that the sub-cores in CG30 were formed by initial fragmentation of a filamentary prestellar core, while those in BHR71 could originate from rotational fragmentation of a single collapsing protostellar core.

31 pages, 10 figures, to be published by ApJ in Sep. 2008