2008A&A...492..735P


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST23:50:35

2008A&A...492..735P - Astronomy and Astrophysics, volume 492, 735-741 (2008/12-4)

Encounter-driven accretion in young stellar clusters - A connection to FUors?

PFALZNER S.

Abstract (from CDS):

The brightness of FUors increases by several magnitudes within one to several years. The currently favoured explanation for this brightness boost is that of dramatically rising accretion from the disc material around a young star. The mechanism leading to this accretion increase is a point of debate. Choosing the Orion nebula cluster as representative, we simulate accretion bursts driven by encounters in dense stellar environments. We investigate whether properties like rise and decay times, event frequency, etc., speak for encounters as a possible cause for FUor phenomena. We combine cluster simulations performed with the Nbody6++ code with particle simulations that describe the effect of a fly-by on the disc around a young star to determine the induced mass accretion. The induced accretion rates, the overall temporal accretion profile, the decay time, and possibly the binarity rate we obtain for encounter-induced accretion agree very well with observations of FUors. However, the rise time of one year observed in some FUors is difficult to achieve in our simulations unless the matter is stored somewhere close to the star and then released after a certain mass limit is transgressed. The severest argument against the FUors phenomenon being caused by encounters is that most FUors are found in environments of low stellar density. We extend the discussion to eccentric binaries and gravitationally unstable discs and find that both models have similar problems in achieving the necessary rise times. We find no conclusive answer as to whether the observed FUors are triggered by encounters. However, it seems an intense accretion burst phase should exist - possibly an FU phase - early on in the development of dense clusters. We predict that in dense young clusters these outbursts should happen predominantly close to the cluster centre and with high mass ratios between the involved stars.

Abstract Copyright:

Journal keyword(s): stars: pre-main sequence - stars: circumstellar matter - stars: early-type

CDS comments: Table 2 : Re 50 N IRS 1 is Reipurth 50 in Simbad.

Simbad objects: 26

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Number of rows : 26

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* V710 Cas Or* 00 36 46.41432 +63 28 56.2224           ~ 83 0
2 V* V710 Cas B FU* 00 36 46.6020931957 +63 28 57.617542780           ~ 50 0
3 NGC 1333 OpC 03 29 11 +31 18.6           ~ 1219 1
4 IC 346 GiG 03 41 44.6801088612 -18 16 01.069437402   13.53   12.28   ~ 44 0
5 [CAR83] PP 13S ISM 04 10 40.7 +38 07 52           ~ 18 1
6 NAME Tau-Aur Complex SFR 04 30 +25.0           ~ 1217 0
7 RAFGL 5123 FU* 04 31 34.07736 +18 08 04.9020           K3V/M3III 811 0
8 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1977 1
9 V* V883 Ori Or* 05 38 18.0974260202 -07 02 25.963144400   14.80       F:I: 107 0
10 RAFGL 5163 Y*O 05 40 27.45024 -07 27 30.0564           ~ 125 1
11 V* FU Ori Or* 05 45 22.3650208559 +09 04 12.296285806   10.72 9.60     F0Iab 708 1
12 V* V1647 Ori Or* 05 46 13.1370923766 -00 06 04.876812846     18.1     ~ 231 1
13 V* V1184 Tau Or* 05 47 03.7744672290 +21 00 34.783877973       14.66   G5III/IVne 35 0
14 V* V912 Mon Or* 06 40 59.3031035066 +09 35 52.395907208         16.50 GIII 23 0
15 V* Z CMa Ae* 07 03 43.1588002461 -11 33 06.230351311 10.51 9.99 8.80     B5/8eq+F5/7 532 3
16 V* V646 Pup Or* 07 50 35.5923632458 -33 06 23.904713538   13.96 12.65 12.04   ~ 62 0
17 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3027 0
18 IRAS 16289-4449 Or* 16 32 32.19264 -44 55 30.6552       15.95   ~ 116 1
19 IRAS 18272+0114 Or* 18 29 49.13016 +01 16 20.6472           ~ 62 1
20 Parsamian 21 FU* 19 29 00.849 +09 38 43.40   15.18 14.07 13.93   F5Iabe 81 1
21 V* V1515 Cyg Or* 20 23 48.0159810586 +42 12 25.780858811   15.26 13.39 12.03   G0/G2Ib 211 0
22 EM* LkHA 190 Or* 20 58 53.7336698326 +44 15 28.384667940   14.26 12.33 12.13   F7/G3I/IIe 476 0
23 HH 448 HH 21 00 31.8 +52 29 17           ~ 17 0
24 EM* LkHA 120 Or* 21 01 09.2068364908 +50 21 44.803310926 13.37 13.09 11.99 11.75   F0/F4-G5 187 1
25 V* V1735 Cyg Or* 21 47 20.6624829527 +47 32 03.856911703           ~ 152 0
26 V* V733 Cep Or* 22 53 33.2582967602 +62 32 23.630788987     18.57   14.63 ~ 35 0

    Equat.    Gal    SGal    Ecl

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2020.07.13-23:50:35

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