2005A&A...439..195V


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.25CET06:14:01

2005A&A...439..195V - Astronomy and Astrophysics, volume 439, 195-203 (2005/8-3)

Line profiles of molecular ions toward the pre-stellar core LDN 1544.

VAN DER TAK F.F.S., CASELLI P. and CECCARELLI C.

Abstract (from CDS):

Velocity profiles of ground state lines of H2D+, HC18O+ and N2H+, observed previously with the CSO and IRAM 30 m telescopes, are modeled with a Monte Carlo radiative transfer program to study the temperature, density and velocity structure of the pre-stellar core LDN 1544. The H2D+ line is double-peaked like that of the other ions, but previous models that fit the HC18O+ and N2H+ profiles are found not to fit the H2D+ data. Matching the H2D+ observations requires at least three modifications to the model at small radii: (1) the density profile must continue to rise inward and not flatten off toward the center; (2) the gas temperature must be nearly constant and not drop inwards significantly; (3) the infall velocity must increase inward, in a fashion intermediate between ``quasi-static'' (ambipolar diffusion) and ``fully dynamic'' (Larson-Penston) collapse. The C18O emission indicates a chemical age of ≲0.1Myr. The effects of a flattened structure and rotation on the line profiles are shown to be unimportant, at least on the scales probed by single-dish telescopes. Alternatively, the H2D+ profile is affected by absorption in the outer layers of the core, if gas motions in these layers are sufficiently small.

Abstract Copyright:

Journal keyword(s): ISM: molecules - circumstellar matter - stars: formation - astrochemistry - molecular processes - line: profiles

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 LDN 1489 DNe 04 04 47.5 +26 19 42           ~ 198 0
2 IRAS 04191+1523 Y*O 04 22 00.43944 +15 30 21.2148           ~ 186 0
3 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3572 0
4 LDN 1544 DNe 05 04 16.6 +25 10 48           ~ 704 0
5 NAME [BM89] L1544 cor 05 04 22.5 +25 11 36           ~ 434 1
6 LDN 1689N DNe 16 32 31 -24 28.6           ~ 108 0

    Equat.    Gal    SGal    Ecl

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2020.11.25-06:14:01

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