2008A&A...488..565C


Query : 2008A&A...488..565C

2008A&A...488..565C - Astronomy and Astrophysics, volume 488, 565-578 (2008/9-3)

Disks around CQ Tauri and MWC758: dense PDR or gas dispersal?

CHAPILLON E., GUILLOTEAU S., DUTREY A. and PIETU V.

Abstract (from CDS):

The overall properties of disks surrounding intermediate PMS stars (HAe) are not yet well constrained by current observations. The disk inclination, which significantly affects spectral energy distribution modeling, is often unknown. We attempted to resolve the disks around CQ Tau and MWC758 to provide accurate constraints on the disk parameters, in particular the temperature and surface density distribution. We report arcsecond resolution observations of dust and CO line emissions with the IRAM array. We also searched for the HCO+ J=1->0 transition. The disk properties are derived using a standard disk model. We use the Meudon PDR code to study the chemistry. The two disks share some common properties. The mean CO abundance is low despite disk temperatures above the CO condensation temperature. Furthermore, the CO surface density and dust opacity have different radial dependence. The CQTau disk appears warmer and perhaps less dense than that of MWC758. Modeling the chemistry, we find that photodissociation of CO is a viable mechanism to explain its low abundance. The photospheric flux is not sufficient for this: a strong UV excess is required. In CQTau, the high temperature is consistent with the expectation for a PDR. The PDR model has difficulty explaining the mild temperatures obtained in MWC758, for which a low gas-to-dust ratio is preferred. A yet, unexplored alternative could be that, despite currently high gas temperatures CO remains trapped in grains, as the models suggest that large grains can be cold enough to prevent thermal desorption of CO. The low inclination of the CQ Tau disk, ∼30°, challenges previous interpretations given for UX Ori - like luminosity variations of this star. We conclude that CO cannot be used as a simple tracer of gas-to-dust ratio, the CO abundance being affected by photodissociation and grain growth.

Abstract Copyright:

Journal keyword(s): stars: circumstellar matter - planetary systems: protoplanetary disks - radio lines: stars

Simbad objects: 20

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Number of rows : 20
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 3C 111 Sy1 04 18 21.2772425736 +38 01 35.801359968   19.75 18.05     ~ 894 1
2 V* BP Tau Or* 04 19 15.8339827632 +29 06 26.926959492   13.13 12.12 11.89   K5/7Ve 632 0
3 NAME Tau-Aur Complex SFR 04 30 +25.0           ~ 1294 0
4 V* V1213 Tau Or* 04 31 37.5055489536 +18 12 24.383952396           K7 540 0
5 V* UZ Tau Y*O 04 32 42.81 +25 52 31.3           M4Ve+M1/3Ve 297 0
6 V* UZ Tau B TT* 04 32 42.8118779016 +25 52 31.198173600   14.07 12.72 13.35   M1/3Ve 142 0
7 V* DM Tau Or* 04 33 48.7336763736 +18 10 09.973460280 14.30 14.82 14.00     M2Ve 579 0
8 EM* LkCa 15 Or* 04 39 17.7911622816 +22 21 03.390090984   13.01 12.03 11.61   K5:Ve 612 1
9 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3926 0
10 V* AB Aur Ae* 04 55 45.8458932216 +30 33 04.292077032 7.20 7.16 7.05 6.96 6.70 A0Ve 992 2
11 HD 31648 Ae* 04 58 46.2655706952 +29 50 36.987625680 7.84 7.78 7.62 7.76 7.43 A5Vep 458 0
12 V* UX Ori Ae* 05 04 29.9878898040 -03 47 14.286732072 10.25 10.93 8.70 9.62 9.43 A4IVe 351 1
13 V* V1366 Ori Ae* 05 16 00.4765181328 -09 48 35.393784012 10.19 10.16 9.84 9.77 9.63 B9.5V 183 0
14 HD 34382 * 05 18 31.1524062456 +33 09 52.715354724   8.11 8.16     B9 7 0
15 HD 36112 Ae* 05 30 27.5285630040 +25 19 57.076288752   8.57 8.27     A8Ve 416 0
16 QSO J0530+13 Bla 05 30 56.4168902136 +13 31 55.151893344     20.0 19.35   ~ 913 1
17 V* CQ Tau Ae* 05 35 58.4666264136 +24 44 54.091450572 11.290 10.780 10.000   8.33 F5IVe 283 0
18 * bet Pic PM* 05 47 17.0876901 -51 03 59.441135 4.13 4.03 3.86 3.74 3.58 A6V 1783 1
19 HD 163296 Ae* 17 56 21.2881851168 -21 57 21.871819008 7.00 6.93 6.85 6.86 6.67 A1Vep 953 0
20 EM* MWC 349 ** 20 32 45.499080 +40 39 36.74124   15.88 13.15 12.13   Bep 753 0

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2022.05.28-09:41:56

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