Interacting binary jets in L1551 IRS 5 protobinary system

Abstract

Rodr??guez et al. (2003b) used Very Large Array (VLA) in addition of Pie Town

antenna (PT antenna) to observe the low mass protostellar system, L1551 IRS 5

at 3.5 cm. Their radio map showed two main results: a number of knots along

the two extend radio jets driven from L1551 IRS 5 and the southern jet shows

a peculiar bend at about 0.006 to the southwest of the driving source. To inves-

tigate how the knots formed and what causes the bend in southern jet, I found

three data sets reliable to make the maps from the VLA online data archive

comprising 1994, 2002 and 2003. The 3.5 cm radio continuum maps of three

epochs showed similar jets structure. I denoted the knots as RK A, B, C, D,

E, F and G. For interpreting the nature of the knots seen in both jets and variations in the intensity/structure of the southern jet, I make the difference

maps for multi-epoch comparison. There are no significant residuals (> 4_) for

above-mentioned knots. We measure the velocities of the RKs relative to RK

A: RK C (19 ± 13 kms?1), RK D (7.5 ± 4.7 kms?1 between epoch 1994 and

2002, 85 ± 20 kms?1 between epoch 2002 and 2003), RK E (72 ± 24 kms?1)

and RK G (24 ± 32 kms?1). And the intrinsic velocity of RK B relative to

southern protostar is 3.8 ± 2.8 kms?1. All of them are insignificant (< 4 _).

However, I detected a positive residual with highly significant (> 6_) in all

difference maps. I denoted it as RK H. And I obtained a significant proper

motion of RK H (128 ± 18 kms?1). RK B, C, D, E, F and G are not likely

formed by enhancement in mass loss or internal shock because their 4_ upper

limit velocities are much slower than jet velocities of their corresponding jet.

They can be interpreted by either the model of interaction of the binary jets or

interaction with ambience cloudlets. Since the flux density of RK H is roughly

constant within 1_ so that it is not likely formed by enhancement in mass loss

but it can be explained by internal shock.