2020A&A...640A...5T


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.26CET14:50:59

2020A&A...640A...5T - Astronomy and Astrophysics, volume 640A, 5-5 (2020/8-1)

Observed sizes of planet-forming disks trace viscous spreading.

TRAPMAN L., ROSOTTI G., BOSMAN A.D., HOGERHEIJDE M.R. and VAN DISHOECK E.F.

Abstract (from CDS):


Context. The evolution of protoplanetary disks is dominated by the conservation of angular momentum, where the accretion of material onto the central star is fed by the viscous expansion of the outer disk or by disk winds extracting angular momentum without changing the disk size. Studying the time evolution of disk sizes therefore allows us to distinguish between viscous stresses or disk winds as the main mechanism of disk evolution. Observationally, estimates of the size of the gaseous disk are based on the extent of CO submillimeter rotational emission, which is also affected by the changing physical and chemical conditions in the disk during the evolution.
Aims. We study how the gas outer radius measured from the extent of the CO emission changes with time in a viscously expanding disk. We also investigate to what degree this observable gas outer radius is a suitable tracer of viscous spreading and whether current observations are consistent with viscous evolution.
Methods. For a set of observationally informed initial conditions we calculated the viscously evolved density structure at several disk ages and used the thermochemical code DALI to compute synthetic emission maps, from which we measured gas outer radii in a similar fashion as observations.
Results. The gas outer radii (R_CO, 90%_) measured from our models match the expectations of a viscously spreading disk: R_CO, 90%_ increases with time and, for a given time, R_CO, 90%_ is larger for a disk with a higher viscosity αvisc. However, in the extreme case in which the disk mass is low (Mdisk≤10–4M) and αvisc is high (≥10–2), R_CO, 90%_ instead decreases with time as a result of CO photodissociation in the outer disk. For most disk ages, R_CO, 90%_ is up to ∼12x larger than the characteristic size Rc of the disk, and R_CO, 90%/Rc_ is largest for the most massive disk. As a result of this difference, a simple conversion of R_CO, 90%_ to αvisc overestimates the true αvisc of the disk by up to an order of magnitude. Based on our models, we find that most observed gas outer radii in Lupus can be explained using viscously evolving disks that start out small (Rc(t=0)≃10AU) and have a low viscosity (αvisc=10–4-10–3).
Conclusions. Current observations are consistent with viscous evolution, but expanding the sample of observed gas disk sizes to star-forming regions, both younger and older, would better constrain the importance of viscous spreading during disk evolution.

Abstract Copyright: © ESO 2020

Journal keyword(s): protoplanetary disks - astrochemistry - radiative transfer - line: formation

Simbad objects: 38

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Number of rows : 38

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 NAME Cha I MoC 11 06 48 -77 18.0           ~ 986 1
2 Sz 65 Or* 15 39 27.7717320499 -34 46 17.209059896   13.11 12.13 11.33 10.76 K7 73 0
3 CD-33 10685 Or* 15 45 12.8670160092 -34 17 30.646921079 12.47 11.56 10.224 9.60 8.685 K3Ve 222 1
4 V* GW Lup Or* 15 46 44.7292759994 -34 30 35.677245389   13.8       M1.5e 86 0
5 THA 15-5 TT* 15 47 56.9433443193 -35 14 34.797849332   14.5 16.2     K7e 64 0
6 CD-35 10525 Or* 15 49 12.1055573607 -35 39 05.053991067 12.19 12.76 11.66 11.15   K7Ve 240 0
7 Sz 76 TT* 15 49 30.7354526514 -35 49 51.418314548   14.4       M3.2 34 0
8 UCAC2 23646111 * 15 53 42.1006106399 -20 49 28.346013512         13.55 M3.4V 16 0
9 WRAY 15-1384 TT* 15 56 02.0991789524 -36 55 28.274442471 14.91 15.05 13.85 12.91 11.86 M1 29 0
10 THA 15-12 Or* 15 56 09.2067120748 -37 56 06.126159332   13.12 11.93 11.45   M0e 258 0
11 Sz 84 TT* 15 58 02.5212129160 -37 36 02.733294310   14.3       M5.0e 52 0
12 WRAY 15-1400 TT* 15 59 16.4714616661 -41 57 10.300292528   13.5 12.0     K7IVe 61 0
13 V* RY Lup Or* 15 59 28.3852522995 -40 21 51.255321659   12.62 9.90     G8/K1IV-V 171 0
14 2MASS J16000236-4222145 Y*O 16 00 02.3596641694 -42 22 14.595263750   16.86 15.46 14.98 13.59 M4 29 0
15 [PBB2002] USco J160018.4-223011 * 16 00 18.4256003665 -22 30 11.559252538           M3e 20 0
16 * del Sco SB* 16 00 20.00528 -22 37 18.1431 1.30 2.20 2.32 2.36 2.49 B0.3IV 697 0
17 V* MY Lup TT* 16 00 44.5199369001 -41 55 30.931594414   12.64 12.17 11.06   K0 62 0
18 [PBB2002] USco J160207.5-225746 Ro* 16 02 07.5768715262 -22 57 46.883841851           M1e 22 0
19 NAME Lup Cloud SFR 16 03 -38.1           ~ 531 0
20 HD 325367 Or* 16 03 05.4914377137 -40 18 25.426543472   11.40 8.50     M0 282 0
21 Sz 133 Y*O 16 03 29.3676884922 -41 40 01.858389664   17.77 16.60 15.78 15.04 K2 34 0
22 2MASS J16035767-2031055 TT* 16 03 57.6711988104 -20 31 05.603641039   13.4   11.73 10.92 K5 45 0
23 [PGZ2001] J160357.9-194210 pr* 16 03 57.9354910711 -19 42 10.906780303           M2e 34 0
24 THA 15-20 TT* 16 07 11.5876160594 -39 03 47.490881982   16.25 14.58 14.11 12.92 M0.5 76 0
25 EPIC 204830786 Em* 16 07 57.9591603107 -20 40 08.675761436   16.6 14.8     ~ 19 0
26 V* V1279 Sco Or* 16 08 22.4935035747 -39 04 46.427826148   14.99 13.66 11.70 11.21 M0.4 88 1
27 [T64] 3 pr* 16 08 23.2470936068 -19 30 00.980264576         11.79 K9e 43 0
28 THA 15-26 Y*O 16 08 25.7651773769 -39 06 01.220655906   16.62 15.43 14.97 13.12 M5 53 0
29 IRAS 16051-3820 Y*O 16 08 30.6992185515 -38 28 26.847010777   11.89 11.15 10.67   K2 39 0
30 V* V1094 Sco TT* 16 08 36.1770068081 -39 23 02.462096497 16.01 15.00 13.48 12.47 11.45 ~ 54 1
31 THA 15-33 TT* 16 08 54.6847312618 -39 37 43.145460615   15.34 13.98 13.29   M1IVe 64 0
32 THA 15-42 Y*O 16 10 51.5851116158 -38 53 13.768173219   15.89 14.48 14.44 12.95 M1e 55 0
33 NAME Upper Sco Association As* 16 12 -23.4           ~ 1054 1
34 [T64] 6 Em* 16 12 39.1668724365 -18 59 28.460261730   15.5   13.99 11.84 K2.5IV 23 1
35 [T64] 7 Y*O 16 14 20.2881608121 -19 06 48.062339327           K5e 51 0
36 NAME ASSOC II SCO As* 16 15 -24.2           ~ 1143 1
37 NAME VLA 1623-243 Y*O 16 26 26.42 -24 24 30.0           ~ 375 0
38 * alf Sco ** 16 29 24.45970 -26 25 55.2094 4.08 2.75 0.91 -0.64 -1.87 M0.5Iab+B3V: 706 0

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2020.10.26-14:50:59

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