Contour maps of 141 GHz continuum emission around 3 young stars are presented in Figure 1. The disklike structures are clearly resolved. The flux densities and beam deconvolved sizes of the disks are 150 mJy and 1.12" x 0.82" for HL Tau, 37 mJy and 0.79" x 0.38" for DO Tau, and 31 mJy and 1.39" x 0.76" for GM Aur. The peaks of the continuum emission are located at («[1950],¿[1950]) = (04h 28m 44.39s, +18d 07m 35.0s) for HL Tau, (04h 35m 24.20s, +26d 04m 54.4s) for DO Tau, and (04h 51m 59.79s, +30d 17m 13.3s) for GM Aur.

Figure 1. Contour maps of 141 GHz continuum emission from the dust particles around the 3 young stars, HL Tau, DO Tau and GM Aur. The contour levels are in steps of —3.0, -11.5, 1.5, 3.0, 4.5, 6.0, 7.5, 9.0, 10.5, 12.0, 15, 20, 25 and 30 times the rms level. The rms levels are 2.6 mJy beam-1 for HL Tau, 1.8 mJy beam-1 for DO Tau and 2.0 mJy beam-1 for GM Aur.

In Figure 2, we show the best fit solutions to the spectral energy distributions (SEDs) of the 3 young stars. Applying a power-law model (discribed below) to the SEDs with the disk radii and the inclination angles which derived from our images, we determined the physical parameters of the disks. The best fit values are summarized in Table 1.

HL Tauri

DO Tauri

HL Tauri

DO Tauri

12 14

12 14

12 14

GM Auriga

GM Auriga

12 14 16

12 14

12 14 16

Figure 2. Spectral energy distributions of the 3 young stars. The 2 mm flux densities are from [1,3,6,9-14],

The flux density Fu emitted from a disk at frequency v can be expressed as

And2Fv = 47TCOS0 X^' B1/(T)(1—exp(—rl//cos^))27rr(¿r,

where d is the distance to the objects (~ 140pc), BV(T) is the Planck function with temperature T, 0 is an inclination angle of the disk (0° for edge-on), and tu is the optical depth due to the dust opacity, (t„ = k„E). The dust opacity coefficient ku at v < 1012Hz is calculated from the following equation, = 0.1(^/1012[Hz])". At u > 1012Hz, the coefficient from the interstellar extinction curve is adopted. The surface density and temperature distributions of the disk are assumed to have power-law forms of E(r) = E0(r/lAU)-p and T(r) = T0(r/ 1AU)~« respectively [1,3,5,6].

Table 1

Best fit parameters of the protoplanetary disks around the 3 young stars

Table 1

Best fit parameters of the protoplanetary disks around the 3 young stars

Source |
HL Tauri |
DO Tauri |
GM Auriga |

disk radius [AU] |
125 ± 2 |
147 ± 6 |
161 ± 4 |

inclination [deg.] |
45 ± 5 |
62 ± 5 |
55 ± 6 |

disk mass [Me] |
0.069±0.003 |
0.004 ± 0.001 |
0.028 ± 0.002 |

1 l+0-4 ^ - ^—x.i |
i-o±8:i | ||

To[ K] |
320 ± 5 |
253 ± 5 |
200 ± 5 |

<7 |
0.47 ± 0.01 |
0.54 ± 0.01 |
0.53 ± 0.01 |

ft |
1.19 ± 0.05 |
0.33 ± 0.11 |
1.02 ± 0.03 |

inner radius [AU] |
0.02 ± 0.01 |
<0.01 |
0.83 ± 0.25 |

Was this article helpful?

## Post a comment