The physical conditions in Gomez's Hamburger (IRAS 18059-3211), a pre-MS rotating disk
Abstract
Aims: We aim to study the structure, dynamics, and physical conditions of Gomez's Hamburger (IRAS 18059-3211; GoHam), and in particular confirm that GoHam mainly consists of a flaring disk in Keplerian rotation around a young, probably pre-MS star.
Methods: We present high resolution SMA maps of 12CO J = 2-1, 13CO J = 2-1, 12CO J = 3-2, and C17O J = 3-2, as well as data on 12CO J = 6-5 and the continuum flux at these wavelengths. Spatial resolutions as high as 1´´ are attained. Except for the C17O data, the dynamical ranges are larger than 10. The maps are compared with a numerical model, which simulates the emission of a rotating disk with the expected general properties of such objects, and a very satisfactory fitting of our maps is obtained. The meaning and reliability of our results are thoroughly discussed.
Results: Our observations allow measurement of the main properties of GoHam on scales of between 1 arcsec ( 5×1015 cm, for the assumed distance, 300 pc) and the total extent of the nebula, 14 arcsec. We are able to measure the global structure of the gas-rich disk, which is found to be flaring, and its dynamics, which is clearly dominated by Keplerian rotation, with a small degree of turbulence. The combination of different lines, in particular of different opacities, allows us to estimate reasonably the distributions of gas temperature and density. We clearly find a significant and sharp increase in temperature at large distances from the equator, accompanied by a decrease in density of the same order. Finally, we identify a condensation in the southern part of the disk that has no counterparts in the northern nebula. This condensation is quite extended (about 5×1015 cm), contains a significant amount of mass (roughly, 6×10-3 M{⊙}), and seems to be associated with a detectable distortion of the global rotation kinematics. We discuss several possible interpretations of that feature.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 2009
- DOI:
- 10.1051/0004-6361/200811233
- arXiv:
- arXiv:0901.4256
- Bibcode:
- 2009A&A...500.1077B
- Keywords:
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- stars: circumstellar matter;
- stars: planetary systems: protoplanetary disks;
- stars: formation;
- stars: individual: Gomez's Hamburger;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 16 pages, 12 figures, 1 pdflatex text file, goha.bbl file, aa.cls style file