Differentiating formation models with new dynamical masses for the PDS 70 protoplanets
Year: 2025
Type: article
Abstract: Hot- and cold-start planet formation models predict differing luminosities for the young, bright planets that direct-imaging surveys are most sensitive to. However, precise mass estimates are required to distinguish between these models observationally. The presence of two directly imaged planets, PDS 70 b and c, in the PDS 70 protoplanetary disk provides us a unique opportunity for dynamical mass measurements since the masses of these planets are currently poorly constrained. Fitting orbital parameters to new astrometry of these planets, taken with VLTI/GRAVITY in the K band, we find 2σ dynamical upper mass limits of 4.9 MJup for b and 13.6 MJup for c. Adding astrometry from the newly proposed planet candidate PDS 70 d into our model, we determine 2σ dynamical upper mass limits of 5.3 MJup, 7.5 MJup, and 2.2 MJup for b, c, and the candidate d, respectively. However, N-body analysis of the orbits’ fit in this case suggests that the inclusion of d makes the system unstable. Using the upper mass limits for b and c, we rule out the coldest-start formation models for both planets, calculating minimum post-formation entropies (S i) of 9.5 kB/baryon and 8.4 kB/baryon, respectively. This places PDS 70 b and c on the growing list of directly imaged planets inconsistent with cold-start formation.
Source: Astronomy and Astrophysics
Authors: David Trevascus, Sarah Blunt, Valentin Christiaens, Elisabeth Matthews, Iain Hammond, Wolfgang Brandner, Jason Wang, Sylvestre Lacour, Arthur Vigan, William O. Balmer, Mickael Bonnefoy, Remo Burn, Gaël Chauvin, Raffaele Gratton, Mathis Houllé, Sasha Hinkley, Jens Kammerer, Laura Kreidberg, Gabriel-Dominique Marleau, Dino Mesa, Gilles Otten, Mathias Nowak, Emily Rickman, Joel Sanchez-Bermudez, Jonas Sauter
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
OpenAlex ID: W4409722644