Forward Modeling the Orbits of Companions to Pulsating Stars from Their Light Travel Time Variations
Abstract
Mutual gravitation between a pulsating star and an orbital companion leads to a time-dependent variation in path length for starlight traveling to Earth. These variations can be used for coherently pulsating stars, such as the δ Scuti variables, to constrain the masses and orbits of their companions. Observing these variations for δ Scuti stars has previously relied on subdividing the light curve and measuring the average pulsation phase in equally sized subdivisions, which leads to undersampling near periapsis. We introduce a new approach that simultaneously forward models each sample in the light curve and show that this method improves upon current sensitivity limits -- especially in the case of highly eccentric and short-period binaries. We find that this approach is sensitive enough to observe Jupiter mass planets around δ Scuti stars under ideal conditions, and use gravity-mode pulsations in the subdwarf B star KIC 7668647 to detect its companion without radial velocity data. We further provide robust detection limits as a function of the signal-to-noise ratio of the pulsation mode and determine that the minimum detectable light travel time amplitude for a typical Kepler δ Scuti is around 2 s. This new method significantly enhances the application of light travel time variations to detecting short-period binaries with pulsating components, and pulsating A-type exoplanet host stars, especially as a tool for eliminating false positives.
- Publication:
-
The Astronomical Journal
- Pub Date:
- May 2020
- DOI:
- 10.3847/1538-3881/ab7d38
- arXiv:
- arXiv:2003.02379
- Bibcode:
- 2020AJ....159..202H
- Keywords:
-
- Asteroseismology;
- Exoplanet detection methods;
- Binary stars;
- Delta Scuti variable stars;
- B subdwarf stars;
- 73;
- 489;
- 154;
- 370;
- 129;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 14 pages, accepted for publication in AJ