Gas, not dust: Migration of TESS/Gaia hot Jupiters possibly halted by the magnetospheres of protoplanetary disks

TL;DR

This study investigates whether gas or dust disks in protoplanetary systems primarily halt the inward migration of hot Jupiters, finding evidence that gas disks around intermediate-mass stars are the key factor.

Contribution

It provides observational evidence that gas disks, rather than dust, set the inner boundary for hot Jupiter orbits around intermediate-mass stars, extending previous low-mass star studies.

Findings

Inner gas disks limit hot Jupiter orbits around intermediate-mass stars.

Results support gas-truncation as the migration halting mechanism across stellar masses.

Hot Jupiters likely form via core accretion and migrate until halted by gas disks.

Abstract

(Abridged) The presence of short-period (< 10 days) planets around main sequence (MS) stars has been associated either with the dust-destruction region or with the magnetospheric gas-truncation radius in the protoplanetary disks that surround them during the pre-MS phase. However, previous analyses have only considered low-mass FGK stars, making it difficult to disentangle the two scenarios. This exploratory study is aimed at testing whether it is the inner dust or gas disk driving the location of short-period, giant planets. By combining TESS and Gaia DR3 data, we identified a sample of 47 intermediate-mass (1.5-3 M$_{\odot}$) MS stars hosting confirmed and firm candidate hot Jupiters. We compared their orbits with the rough position of the inner dust and gas disks, which are well separated around their Herbig stars precursors. We also made a comparison with the orbits of confirmed hot Jupiters around a similarly extracted TESS/Gaia sample of low-mass sources (0.5-1.5 M$_{\odot}$). Our results suggest that the inner gas (and not the dust) disk limits the innermost orbits of hot Jupiters around intermediate-mass stars. These findings also provide tentative support to previous works that have claimed this is indeed the case for low-mass sources. We propose that hot Jupiters could be explained via a combination of the core-accretion paradigm and migration up to the gas-truncation radius, which may be responsible for halting inward migration regardless of the stellar mass regime. Larger samples of intermediate-mass stars with hot Jupiters are necessary to confirm our hypothesis, which implies that massive Herbig stars without magnetospheres (> 3-4 M$_{\odot}$) may be the most efficient in swallowing their newborn planets.