TY - JOUR
T1 - A deeply embedded young protoplanetary disk around L1489 IRS observed by the Submillimeter Array
AU - Brinch, C.
AU - Crapsi, A.
AU - Jørgensen, J. K.
AU - Hogerheijde, M. R.
AU - Hill, T.
PY - 2007/12
Y1 - 2007/12
N2 - Context. Circumstellar disks are expected to form early in the process that leads to the formation of a young star, during the collapse of the dense molecular cloud core. Currently, it is not well understood at what stage of the collapse the disk is formed or how it subsequently evolves. Aims. We aim to identify whether an embedded Keplerian protoplanetary disk resides in the L1489 IRS system. Given the amount of envelope material still present, such a disk would respresent a very young example of a protoplanetary disk. Methods. Using the Submillimeter Array we have observed the HCO
+ J = 3-2 line with a resolution of about 1". At this resolution a protoplanetary disk with a radius of a few hundred AUs should be detectable, if present. Radiative transfer tools are used to model the emission from both continuum and line data. Results. We find that these data are consistent with theoretical models of a collapsing envelope and Keplerian circumstellar disk. Models reproducing both the spectral energy distribution and the interferometric continuum observations reveal that the disk is inclined by 40°, which is significantly different to the surrounding envelope (74°). Conclusions. This misalignment of the angular momentum axes may be caused by a gradient within the angular momentum in the parental cloud, or if L1489 IRS is a binary system rather than just a single star. In the latter case, future observations looking for variability at sub-arcsecond scales may be able to constrain these dynamical variations directly. However, if stars form from turbulent cores, the accreting material will not have a constant angular momentum axis (although the average is well defined and conserved), in which case it is more likely to have a misalignment of the angular momentum axes of the disk and the envelope.
AB - Context. Circumstellar disks are expected to form early in the process that leads to the formation of a young star, during the collapse of the dense molecular cloud core. Currently, it is not well understood at what stage of the collapse the disk is formed or how it subsequently evolves. Aims. We aim to identify whether an embedded Keplerian protoplanetary disk resides in the L1489 IRS system. Given the amount of envelope material still present, such a disk would respresent a very young example of a protoplanetary disk. Methods. Using the Submillimeter Array we have observed the HCO
+ J = 3-2 line with a resolution of about 1". At this resolution a protoplanetary disk with a radius of a few hundred AUs should be detectable, if present. Radiative transfer tools are used to model the emission from both continuum and line data. Results. We find that these data are consistent with theoretical models of a collapsing envelope and Keplerian circumstellar disk. Models reproducing both the spectral energy distribution and the interferometric continuum observations reveal that the disk is inclined by 40°, which is significantly different to the surrounding envelope (74°). Conclusions. This misalignment of the angular momentum axes may be caused by a gradient within the angular momentum in the parental cloud, or if L1489 IRS is a binary system rather than just a single star. In the latter case, future observations looking for variability at sub-arcsecond scales may be able to constrain these dynamical variations directly. However, if stars form from turbulent cores, the accreting material will not have a constant angular momentum axis (although the average is well defined and conserved), in which case it is more likely to have a misalignment of the angular momentum axes of the disk and the envelope.
KW - Circumstellar matter
KW - ISM: individual objects: L1489 IRS
KW - Stars: formation
KW - Submillimeter
UR - http://www.scopus.com/inward/record.url?scp=36549078169&partnerID=8YFLogxK
U2 - 10.1051/0004-6361:20078249
DO - 10.1051/0004-6361:20078249
M3 - Journal article
AN - SCOPUS:36549078169
SN - 0004-6361
VL - 475
SP - 915
EP - 923
JO - Astronomy and Astrophysics Supplement Series
JF - Astronomy and Astrophysics Supplement Series
IS - 3
ER -