The TW Hya system is perhaps the closest analog to the early solar nebula. We have used the Very Large Array to image TW Hya at wavelengths of 7 mm and 3.6 cm with resolutions 0.′′1 (~5 AU) and 1.′′0 (~50 AU), respectively. The 7 mm emission is extended and appears dominated by a dusty disk of radius >50 AU surrounding the star. The 3.6 cm emission is unresolved and likely arises from an ionized wind or gyrosynchrotron activity. The dust spectrum and spatially resolved 7 mm images of the TW Hya disk are fitted by a simple model with temperature and surface density described by radial power laws, T(r)(alpha)r^−0.5 and Sigma(r)(alpha) r^−1. These properties are consistent with an irradiated gaseous accretion disk of mass ~0.03 M⊙ with an accretion rate ~10−^8 M⊙ yr^−1 and viscosity parameter alpha= 0.01. The estimates of mass and mass accretion rates are uncertain as the gas-to-dust ratio in the TW Hya disk may have evolved from the standard interstellar value (Refer to PDF file for exact formulas).

Publication Date



Also archived in: arXiv: astro-ph/0005019 v1 1 May 2000 This research was partially supported by NASA Origins of Solar Systems Program grant NAG5-8195. LFR acknowledges the support of CONACyT, Mexico We thank Lee Hartmann and Nuria Calvet for valuable discussions about irradiated accretion disks.ISSN:1538-4365 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)


RIT – Main Campus