1 research outputs found
Dynamical mass measurements of two protoplanetary discs
ALMA observations of line emission from planet forming discs have
demonstrated to be an excellent tool to probe the internal disc kinematics,
often revealing subtle effects related to important dynamical processes
occurring in them, such as turbulence, or the presence of planets, that can be
inferred from pressure bumps perturbing the gas motion, or from detection of
the planetary wake. In particular, we have recently shown for the case of the
massive disc in Elias 2-27 how one can use such kind of observations to measure
deviations from Keplerianity induced by the disc self-gravity, thus
constraining the total disc mass with good accuracy and independently on mass
conversion factors between the tracer used and the total mass. Here, we refine
our methodology and extend it to two additional sources, GM Aur and IM Lup, for
which archival line observations are available for both the 12CO and the 13CO
line. For IM Lup, we are able to obtain a consistent disc mass of Mdisc=0.1
Msun, implying a disc-star mass ratio of 0.1 (consistent with the observed
spiral structure in the continuum emission) and a gas/dust ratio of ~ 65
(consistent with standard assumptions), with a systematic uncertainty by a
factor ~2 due to the different methods to extract the rotation curve. For GM
Aur, the two lines we use provide slightly inconsistent rotation curves, that
cannot be attributed only to a difference in the height of the emitting layer,
nor to a vertical temperature stratification. Our best fit disc mass
measurement is Mdisc=0.26Msun, implying a disc-star mass ratio of ~0.35 and a
gas/dust ratio of ~130... ABRIDGEDComment: 14 pages, 10 figures, MNRAS in pres