1 / 21

Discs around A-type and related stars

Discs around A-type and related stars. Vladimir Grinin. Pulkovo Observatory of RAS. General properties of young disks The dissipative processes The Inner regions of p-p discs Interaction of discs with the low-mass companions The transitional and debris discs. A stars, Moscow 2013.

rowa
Download Presentation

Discs around A-type and related stars

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Discs around A-type and related stars Vladimir Grinin Pulkovo Observatory of RAS • General properties of young disks • The dissipative processes • The Inner regions of p-p discs • Interaction of discs with the low-mass companions • The transitional and debris discs A stars, Moscow 2013

  2. Recent reviews: Dullemond and Monnier 2010, The Inner Regions of Protoplanetary Disks Williams and Cieza 2011, Protoplanetary Disks and Their Evolution Initial conditions: Gas to dust – 100:1 MRN dust

  3. The density distribution for the disc calculations is based on the canonical description of the alpha-disk developed by Shakura & Sunyaev (1973) Disk outer-radius is a parameter Flared discs It is assumed that gas and dust are thermally coupled

  4. near-infrared Discs in IR and mm- wavelengths • shadowed region • magnetospheric • accretion Tsub = 1600 K • gaseous inner disk Disc reprocess the stellar radiation. The viscos heating is important only at high mass accretion rate > 10E-6 • optically thick gas • star • inner disk rim • 0.5 AU Dullemond et al. 2010 • Dust-free inner hole • Puffed-up inner rim (Natta et al. 2001) • Shape of the inner rim • Shadowed region (Dullemond et al. • 2001) M disc = 0.01- 0.1 M sun credit: Dullemond et al. 2006

  5. Contribution of the inner (gaseous) disc Muzerolle et al. 2004

  6. SED + interferometry isthe most effective way KK Oph, Kreplin et al. 2013, VLTI inclination = 70 deg.

  7. SED + Interferometry (Keck) AB Aur Tannirkulam et al. 2008

  8. Disc winds Blandford & Payne (1982) Königl & Salmeron 2010 (review) Safier 1993 – dusty disc wind

  9. Bans and Konigl 2012 – NIR excess AB Aur Tannirkulam et al. 2008 Tambovtseva & Grinin 2008 - extinction Grinin & Tambovtseva 2011, disc wind in HAEs

  10. Observational manifestations of CS discs • In the visual wavelengths: • The scattered radiation  intrinsic linear polarization of YSO (Bastien & Landstreet 1979) • 2) Variable CS extinction  UX Ori stars (Grinin et al. 1991) WW Vul 3. The forbidden lines [OI] 6300 A)

  11. The disc images AB Aur (Sp = A0), Spiral waves, Hashimoto et al. 2011 the polarized intensity (PI) image

  12. 1.3 mm image of AB Aur from Dutrey et al. (2012) ALMA will be able to reveal the structure of the protoplanetary discs in much more details.!

  13. The asymmetric discs LkHa 101, Tuthill et al. 2001 Demidova et al. 2013 SPH model: the low-mass companion on the inclined orbit

  14. Disc dissipation The disc life time ~ 10 Myr (Strom et al. 1993) Grain growth and dust settling Grain growth has a strong radial dependence due to the decreasing density and rotational velocity with increasing radius (Blum & Wurm 2008). Growth is very fast (10000 years). Fragmentation – growth- semi-equilibrium The disc dissipation starts from the inner region of CS disc and leads to the formation of thetransitional discs. . (Zuckerman et al. 1995; Haisch et al. 2001) The central cavity may be also due to the dynamical clearing by a companion, possibly planetary (Artymowicz & Lubow 1994).

  15. Disc dissipation Viscous transport and the gas accretion Shakura & Sunyaev (1973) – MHD – turbulence. Garcia Lopez et al. 2006 Photoevaporation by radiation from the central stars This mechanism was elaborated by Hollenbach et al. (1994) for hot YSOs and CTTS. In the case of HAE stars it is not very actual, since these stars are weaker sources of X-ray and far ultraviolet radiation.

  16. Interaction of discs with the low-mass companions

  17. Demidova et al. 2010

  18. Photometric catastrophes in UXORs What was happened with CQ Tau? CQ Tau (1895-2003); Grinin et al. (2008) Interaction of planet with CS disk – migration – destruction in the star vicinity?

  19. Debis discs Schneider et al. 2005 The well known examples of debris discs around A-stars

  20. AU Mic is a less massive sister star β Pic, member of the same moving group. Debis discs Fitzgerald et al. 2007, JHK composite image, Keck II Wilner et al. 2012 Planetesimals collisions, secondary dust, Wyatt 2008 Thermal and scattered radiation AU r ~ 50 AU

  21. Thank you for your attention

More Related