2011A&A...533A..34H


Query : 2011A&A...533A..34H

2011A&A...533A..34H - Astronomy and Astrophysics, volume 533A, 34-34 (2011/9-1)

Dense core formation by fragmentation of velocity-coherent filaments in L1517.

HACAR A. and TAFALLA M.

Abstract (from CDS):

Low-mass star-forming cores differ from their surrounding molecular cloud in turbulence, shape, and density structure. We aim to understand how dense cores form out of the less dense cloud material by studying the connection between these two regimes. We observed the L1517 dark cloud in C18O(1-0), N2H+(J=1-0), and SO(JN=32-21) with the FCRAO 14m telescope, and in the 1.2mm dust continuum with the IRAM 30m telescope. Most of the gas in the cloud lies in four filaments that have typical lengths of 0.5pc. Five starless cores are embedded in these filaments and have chemical compositions indicative of different evolutionary stages. The filaments have radial profiles of C18O(1-0) emission with a central flattened region and a power-law tail, and can be fitted approximately as isothermal, pressure-supported cylinders. The filaments, in addition, are extremely quiescent. They have subsonic internal motions and are coherent in velocity over their whole length. The large-scale motions in the filaments can be used to predict the velocity inside the cores, indicating that core formation has not decoupled the dense gas kinematically from its parental material. In two filaments, these large-scale motions consist of oscillations in the velocity centroid, and a simple kinematic model suggests that they may be related to core-forming flows. Core formation in L1517 seems to have occurred in two steps. First, the subsonic, velocity-coherent filaments have condensed out of the more turbulent ambient cloud. Then, the cores fragmented quasi-statically and inherited the kinematics of the filaments. Turbulence dissipation has therefore occurred mostly on scales on the order of 0.5pc or larger, and seems to have played a small role in the formation of the individual cores.

Abstract Copyright:

Journal keyword(s): ISM: clouds - ISM: molecules - ISM: kinematics and dynamics - ISM: structure - stars: formation - radio lines: ISM

Simbad objects: 22

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Number of rows : 22
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 ACO 426 ClG 03 19 47.2 +41 30 47           ~ 2149 1
2 NAME [BM89] B5 DNe 03 47 38.3 +32 52 43           ~ 221 0
3 LDN 1471 DNe 03 48.0 +32 54           ~ 312 0
4 V* IK Tau OH* 03 53 28.8924743304 +11 24 21.895183368 16.99 17.03 13.39 7.29 3.20 M7-11 617 0
5 NAME [BM89] L1498 PoC 04 10 51.4 +25 09 58           ~ 187 0
6 LDN 1498 DNe 04 11.0 +24 58           ~ 271 0
7 NAME Tau-Aur Complex SFR 04 30 +25.0           ~ 1317 0
8 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4094 0
9 LDN 1496 DNe 04 43.2 +32 06           ~ 8 0
10 LDN 1505 DNe 04 48.2 +31 05           ~ 8 0
11 LDN 1513 DNe 04 52.0 +30 50           ~ 16 0
12 LDN 1515 DNe 04 53.2 +30 55           ~ 5 0
13 LDN 1517C PoC 04 54 47.4 +30 34 48           ~ 20 0
14 LDN 1517A PoC 04 55 06.3 +30 33 40           ~ 25 0
15 [LM99] L1517B-2 cor 04 55 08.1 +30 42 49           ~ 5 0
16 NAME [BM89] L1517B cor 04 55 18.8 +30 38 04           ~ 139 0
17 LDN 1517 DNe 04 55 45 +30 33.0           ~ 111 0
18 V* AB Aur Ae* 04 55 45.8458932216 +30 33 04.292077032 7.20 7.16 7.05 6.96 6.70 A0Ve 1012 2
19 LDN 1517D PoC 04 55 48.1 +30 38 46           ~ 15 0
20 V* SU Aur Or* 04 55 59.3866872552 +30 34 01.499608092   10.33 9.30 9.17   G2IIIne 574 0
21 [RLK73] IRc 2 IR 05 35 14.51548 -05 22 30.5943           ~ 618 1
22 [CCE98b] 011.11-0.12 Cld 18 10.5 -19 23           ~ 91 1

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2023.01.31-08:39:37

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