Takuya Ohtani (Osaka University Theoretical Astrophysics Group D2) Collaborator: Toru Tsuribe(Osaka Univ.)

Size: px

Start display at page:

Download "Takuya Ohtani (Osaka University Theoretical Astrophysics Group D2) Collaborator: Toru Tsuribe(Osaka Univ.)"

Alannah Austin
5 years ago
Views:

1 Simultaneous Gowth of a Potosta and a Young Cicumstella Disk in the Ealy Phase of Disk Fomation * Takuya Ohtani (Osaka Univesity Theoetical Astophysics Goup D2) Collaboato: Tou Tsuibe(Osaka Univ.) 1

2 Abstact The gowing pocess of the young potosta and the cicumstella disk is investigated. We focus on the viscous evolution of the non isolated disk subject to mass loading fom the envelope in the ealy phase of main accetion. We study the oigin of suface density distibution of the disk and the oigin of the disk to sta mass atio by numeically solving unsteady evolution of one dimensional axisymmetic model fo viscous accetion disk. Finally, the P V diagam of the disk in ou model dlis shown in ode to compae with the obsevations of the sta foming egion. 2

3 1.Intoduction 2.Models Outlines 2.1 Accetion pocess onto the disk 2.2 Accetion pocess onto the sta 3.Results 3.1 Suface density pofile 3.2 Masses 3.3 compaison with the obsevation 4.Conclusion 3

4 1I 1.Intoduction Cloud coe collapse angula momentum tanspot mass edistibution q Potosta + disk Potoplanetay disks ae the bithplace of planets. It is impotant to know the foming mechanism of young disks. As a esult of gavitational ti collapse of a igidly otating cloud coe, a small cental sta and a massive disk is expected as an equilibium state if one assumes the consevation of angula momentum with a typical amount. 4

5 1. Intoduction Howeve, obsevation indicates the lowe mass disk than pedicted d above equilibium i state. tt An efficient tanspot of angula momentum is expected. It will dive the mass accetion flow onto the cental sta to decease the disk mass. This accetion flow is impotant to detemine the disk to sta mass atio. The unsteady and viscous evolution of the disk is studied dtki taking into account of the simultaneous gowth of the disk and the cental sta. 5

6 2.Models We conside the model in which it is assumed that disk mass is fueled by infalling envelope, and simultaneously loses its mass via accetion onto the cental sta. envelope infall accetion sta disk The simultaneous gowth of the disk and sta includes two pocesses. Accetion fom an infalling envelope to the disk Accetion fom the disk onto the cental sta (viscous mass accetion) 6

by Saigo& Hanawa(1998) The disk fomation following the unaway collapse of

7 Models 2.1 Accetion fom an infalling envelope to a disk Self Simila solution given by Saigo& Hanawa(1998) The disk fomation following the unaway collapse of a otating tti cloud coe Axisymmetic and inviscid isothemal flow Mass accetion ate of isothemal collapse depends d on the speed of otation ti 7

8 Models Axisymmetic dynamical flow onto the disk is assumed in this model. Solution Hunte (pai solution fo Lason(1969) and Penston(1969)), Saigo & Hanawa Shu Collapse Dynamical Quasi staticstatic 8 8

9 Models 2.2 Accetion fom the disk onto the cental sta Basic equations axisymmetic i thin disk Continuity Equation Equation of motion Equation fo consevation of the angula momentum Standad accetion disk (Pingle1981) Σ + t v t t + v ( Σv )= 0 v 2 cs = Σ Σv Σ F + 2 φ v 3 Ω ( Σv ) + ( v ) = νσ φ φ Gavitational foce Viscous coefficient ν = αc s h h ~ c s Ω 9

10 Models Appoximation Pessue gadient foce is negligible. Accetion speed within the disk is sufficiently slow. The above equations can be combined to Σ t 1 = 1 ( v ) φ νσ 3 Ω Tempatue (baotopic EOS) Rdil Radial pofiles of the inviscidi iddisk (Initial condition of the disk fo viscous mass accetion) ( ) 1 GM j = ω ( ) Σ = Σ, M disk 1 c s Saigo&Hanawa(1998) 10

11 3.1 Suface density pofile 3Re 3.Results temp * Submitted to PASJ 11

12 3.2 Masses M disk M * Submitted to PASJ 12

13 3.3 Compaison with the obsevation Lee,C., F.,2010 ApJ,725,712 P V diagam Lee( 2010) Position n(au) Velocity(km/s) Ou esults The existence of the heavy disk 13

14 14

15 Conclusion 15

Lecture 24 Stability of Molecular Clouds

Lecture 24 Stability of Molecular Clouds Lectue 4 Stability of Molecula Clouds 1. Stability of Cloud Coes. Collapse and Fagmentation of Clouds 3. Applying the iial Theoem Refeences Oigins of Stas & Planetay Systems eds. Lada & Kylafis http://cfa-www.havad.edu/cete