2011A&A...534A..44W


Query : 2011A&A...534A..44W

2011A&A...534A..44W - Astronomy and Astrophysics, volume 534A, 44-44 (2011/10-1)

The unusual protoplanetary disk around the T Tauri star ET Chamaeleontis.

WOITKE P., RIAZ B., DUCHENE G., PASCUCCI I., LYO A.-R., DENT W.R.F., PHILLIPS N., THI W.-F., MENARD F., HERCZEG G.J., BERGIN E., BROWN A., MORA A., KAMP I., ARESU G., BRITTAIN S., DE GREGORIO-MONSALVO I. and SANDELL G.

Abstract (from CDS):

We present new continuum and line observations, along with modelling, of the faint (6-8)Myr old T Tauri star ET Cha belonging to the η Chamaeleontis cluster. We have acquired Herschel/PACS photometric fluxes at 70µm and 160µm, as well as a detection of the [OI]63µm fine-structure line in emission, and derived upper limits for some other far-IR OI, CII, CO and o-H2O lines. These observations were carried out in the frame of the open time key programme GASPS, where ET Cha was selected as one of the science demonstration phase targets. The Herschel data is complemented by new simultaneous ANDICAM B-K photometry, new HST/COS and HST/STIS UV-observations, a non-detection of COJ=3-2 with APEX, re-analysis of a UCLES high-resolution optical spectrum showing forbidden emission lines like [OI]6300Å, [SII]6731Å and 6716Å, and [NII]6583Å, and a compilation of existing broad-band photometric data. We used the thermo-chemical disk code ProDiMo and the Monte-Carlo radiative transfer code MCFOST to model the protoplanetary disk around ET Cha. The paper also introduces a number of physical improvements to the ProDiMo disk modelling code concerning the treatment of PAH ionisation balance and heating, the heating by exothermic chemical reactions, and several non-thermal pumping mechanisms for selected gas emission lines. By applying an evolutionary strategy to minimise the deviations between model predictions and observations, we find a variety of united gas and dust models that simultaneously fit all observed line and continuum fluxes about equally well. Based on these models we can determine the disk dust mass with confidence, Mdust≃(2-5)x10–8M whereas the total disk gas mass is found to be only little constrained, Mgas≃(5x10–5-3x10–3)M. Both mass estimates are substantially lower than previously reported. In the models, the disk extends from 0.022AU (just outside of the co-rotation radius) to only about 10AU, remarkably small for single stars, whereas larger disks are found to be inconsistent with the COJ=3-2 non-detection. The low velocity component of the [OI]6300Å emission line is centred on the stellar systematic velocity, and is consistent with being emitted from the inner disk. The model is also consistent with the line flux of H2v=1-0 S(1) at 2.122µm and with the [OI]63µm line as seen with Herschel/PACS. An additional high-velocity component of the [OI]6300Å emission line, however, points to the existence of an additional jet/outflow of low velocity 40-65km/s with mass loss rate ≃10–9M/yr. In relation to our low estimations of the disk mass, such a mass loss rate suggests a disk lifetime of only ∼0.05-3Myr, substantially shorter than the cluster age. If a generic gas/dust ratio of 100 was assumed, the disk lifetime would be even shorter, only ∼3000yrs. The evolutionary state of this unusual protoplanetary disk is discussed.

Abstract Copyright:

Journal keyword(s): stars: pre-main sequence - disks - astrochemistry - radiative transfer - line: formation - stars: protoplanetary individual: ET Cha

Simbad objects: 18

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Number of rows : 18
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 V* EG Cha Or* 08 36 56.2143359952 -78 56 45.633633000   11.82 10.457   9.010 K4Ve 92 0
2 * eta Cha * 08 41 19.5125857944 -78 57 48.105898056 5.02 5.351 5.453     B8V 224 0
3 V* ES Cha Or* 08 41 30.3105474648 -78 53 06.477949932     17.07     M4 40 0
4 V* EH Cha Or* 08 41 37.0144539384 -79 03 30.535583220     14.4 14.011   M3 54 0
5 HD 75505 * 08 41 44.7049093968 -79 02 53.258689068   7.55 7.38     A1V 50 0
6 V* EI Cha Or* 08 42 23.7595500240 -79 04 02.976309552     12.7     K7 60 0
7 V* EK Cha Or* 08 42 27.0967343784 -78 57 47.910415932   16.659 15.153 14.893   M5 70 0
8 NAME eta Cha Association OpC 08 42 33 -78 57.8           ~ 351 0
9 V* EL Cha Or* 08 42 38.7832034688 -78 54 42.736732812   15.540 14.081 13.778   M2 53 0
10 V* EM Cha Or* 08 43 07.2443828304 -79 04 52.483961064     10.8     K3 55 0
11 * 9 Cha SB* 08 43 12.1984130688 -79 04 12.368512452   6.28 6.07     A7V 221 0
12 V* ET Cha Or* 08 43 18.5853516024 -79 05 18.232481832     13.97     M2 77 0
13 V* EN Cha Or* 08 44 16.421808 -78 59 08.06316   16.425 14.967 14.688   M4 59 0
14 V* EO Cha Or* 08 44 31.8938144088 -78 46 31.143275076     12.531   10.646 M0 70 0
15 V* EP Cha Or* 08 47 01.6439909496 -78 59 34.380161016     11.1     K5 86 0
16 V* EQ Cha TT* 08 47 56.7585043512 -78 54 53.185560516   14.777 13.308 12.802 10.795 M3 77 0
17 V* TW Hya TT* 11 01 51.9053285064 -34 42 17.033218380   11.94 10.50 10.626 9.18 K6Ve 1787 1
18 CPD-68 1894 TT* 13 22 07.5421944624 -69 38 12.219391716   11.38 10.393   9.117 K1Ve 146 0

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2023.01.27-21:47:40

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