A NICMOS Direct Imaging Search for Giant Planets around the Single White Dwarfs in the Hyades

TL;DR

This study used NICMOS imaging to search for giant planets around seven white dwarfs in the Hyades, finding no evidence of planetary companions larger than 10 Jupiter masses beyond 0.5 arcsec separation.

Contribution

First direct imaging search for giant planets around white dwarfs in the Hyades, providing constraints on planetary presence post-stellar evolution.

Findings

No planetary mass companions detected above 10 Jupiter masses.

Sensitive to companions at separations larger than 0.5 arcsec.

Results consistent with simulations of planet survival and migration.

Abstract

We report preliminary results from our search for massive giant planets (6-12 Jupiter masses) around the known seven single white dwarfs in the Hyades cluster at sub-arcsec separations. At an age of 625 Myr, the white dwarfs had progenitor masses of about 3 solar masses, and massive gaseous giant planets should have formed in the massive circumstellar disks around these ex-Herbig A0 stars, probably at orbital separations similar or slightly larger than that of Jupiter. Such planets would have survived the post-Main-Sequence mass loss of the parent star and would have migrated outward adiabatically to a distance of about 25 AU. At the distance of the Hyades (45 pc) this corresponds to an angular separation of 0.5 arcsec. J and H magnitudes of these giants are in the range of 20.5-23.3 mag, which can be resolved with NICMOS. The achieved sensitivities and contrast ratios agree well with simulations. Preliminary evaluation of the NICMOS data set did not reveal any evidence for neither planetary mass companions with masses down to about 10 Jupiter masses nor brown dwarfs around any of the seven white dwarfs for separations larger than 0.5 arcsec.