2015A&A...577A.102V


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.25CET07:38:02

2015A&A...577A.102V - Astronomy and Astrophysics, volume 577A, 102-102 (2015/5-1)

Chemical tracers of episodic accretion in low-mass protostars.

VISSER R., BERGIN E.A. and JORGENSEN J.K.

Abstract (from CDS):

Accretion rates in low-mass protostars can be highly variable in time. Each accretion burst is accompanied by a temporary increase in luminosity, heating up the circumstellar envelope and altering the chemical composition of the gas and dust. This paper aims to study such chemical effects and discusses the feasibility of using molecular spectroscopy as a tracer of episodic accretion rates and timescales. We simulate a strong accretion burst in a diverse sample of 25 spherical envelope models by increasing the luminosity to 100 times the observed value. Using a comprehensive gas-grain network, we follow the chemical evolution during the burst and for up to 105yr after the system returns to quiescence. The resulting abundance profiles are fed into a line radiative transfer code to simulate rotational spectra of C18O, HCO+, H13CO+, and N2H+ at a series of time steps. We compare these spectra to observations taken from the literature and to previously unpublished data of HCO+ and N2H+ 6-5 from the Herschel Space Observatory. The bursts are strong enough to evaporate CO throughout the envelope, which in turn enhances the abundance of HCO+ and reduces that of N2H+. After the burst, it takes 103-104yr for CO to refreeze and for HCO+ and N2H+ to return to normal. The H2O snowline expands outwards by a factor of ∼10 during the burst; afterwards, it contracts again on a timescale of 102-103yr. The chemical effects of the burst remain visible in the rotational spectra for as long as 105yr after the burst has ended, highlighting the importance of considering luminosity variations when analyzing molecular line observations in protostars. The spherical models are currently not accurate enough to derive robust timescales from single-dish observations. As follow-up work, we suggest that the models be calibrated against spatially resolved observations in order to identify the best tracers to be used for statistically significant source samples.

Abstract Copyright:

Journal keyword(s): stars: formation - stars: protostars - circumstellar matter - accretion, accretion disks - astrochemistry

Simbad objects: 35

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Number of rows : 35

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 1448 DNe 03 22.5 +30 35           ~ 469 0
2 IRAS F03226+3033 Y*O 03 25 38.83 +30 44 06.2           ~ 304 0
3 [JCC87] IRAS 2A Y*O 03 28 55.55 +31 14 36.7           ~ 405 3
4 NAME HH 7-11 FIR 03 29 03.9 +31 16 06           ~ 333 0
5 [JCC87] IRAS 4A Y*O 03 29 10.49 +31 13 30.8           ~ 611 1
6 [JCC87] IRAS 4 FIR 03 29 10.9 +31 13 26           ~ 468 0
7 NGC 1333 OpC 03 29 11 +31 18.6           ~ 1235 1
8 [JCC87] IRAS 4B Y*O 03 29 12.058 +31 13 02.05           ~ 562 0
9 LDN 1489 DNe 04 04 47.5 +26 19 42           ~ 198 0
10 RAFGL 5123 Y*O 04 31 34.07736 +18 08 04.9020           K3V/M3III 816 0
11 IRAS 04361+2547 Y*O 04 39 13.89767 +25 53 20.6340           ~ 185 1
12 IRAS 04365+2535 Y*O 04 39 35.19360 +25 41 44.7252           ~ 242 0
13 LDN 1527 DNe 04 39 53 +25 45.0           ~ 508 0
14 TMC-1 MoC 04 41 45.9 +25 41 27           ~ 1382 0
15 V* FU Ori Or* 05 45 22.3650208559 +09 04 12.296285806   10.72 9.60     F0Iab 721 1
16 2MASS J08254384-5100326 Y*O 08 25 43.85 -51 00 32.7           ~ 298 1
17 IRAS 11051-7706 Y*O 11 06 46.025 -77 22 29.67           ~ 71 0
18 BHR 71 MoC 12 01 36.810 -65 08 49.22           ~ 120 0
19 V* DK Cha Or* 12 53 17.2028372976 -77 07 10.727661977           F0 132 0
20 IRAS 15398-3359 Y*? 15 43 02.21016 -34 09 07.7112       18.38 21.72 ~ 131 0
21 HD 325367 Or* 16 03 05.4914377137 -40 18 25.426543472   11.40 8.50     M0 285 0
22 GSS 30 Y*O 16 26 21.38160 -24 23 04.0524           ~ 200 1
23 Elia 2-29 Y*O 16 27 09.43032 -24 37 18.7716           ~ 267 1
24 IRAS 16285-2355 Y*O 16 31 35.65752 -24 01 29.4708           ~ 106 0
25 HBC 650 TT* 16 34 29.32 -15 47 01.4           K3.0 165 2
26 NAME LDN 483-mm mm 18 17 29.8 -04 39 38           ~ 18 0
27 NAME SH 2-68 FIR 1 cor 18 29 49.63 +01 15 21.9           ~ 238 2
28 NAME Serpens SMM 4 cor 18 29 57.1 +01 13 15           ~ 123 0
29 NAME SERPENS SMM 3 smm 18 29 59.7 +01 14 00           ~ 85 1
30 2MASS J19014805-3657219 Y*O 19 01 48.056 -36 57 21.95           ~ 96 0
31 V* V710 CrA Or* 19 01 50.67792 -36 58 09.6132           K7: 117 0
32 NAME LDN 723-mm smm 19 17 53.70 +19 12 20.0           ~ 15 0
33 LDN 723 DNe 19 18 12 +19 13.6           ~ 153 0
34 LDN 663 DNe 19 36 55 +07 34.4           ~ 562 0
35 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 493 0

    Equat.    Gal    SGal    Ecl

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2020.11.25-07:38:02

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