A Revised Exoplanet Yield from the Transiting Exoplanet Survey Satellite (TESS) (1804.05050v2)

Abstract: The Transiting Exoplanet Survey Satellite (TESS) has a goal of detecting small planets orbiting stars bright enough for mass determination via ground-based radial velocity observations. Here we present estimates of how many exoplanets the TESS mission will detect, physical properties of the detected planets, and the properties of the stars that those planets orbit. This work uses stars drawn from the TESS Input Catalog Candidate Target List and revises yields from prior studies that were based on Galactic models. We modeled the TESS observing strategy to select approximately 200,000 stars at 2-minute cadence, while the remaining stars are observed at 30-min cadence in full-frame image data. We placed zero or more planets in orbit around each star, with physical properties following measured exoplanet occurrence rates, and used the TESS noise model to predict the derived properties of the detected exoplanets. In the TESS 2-minute cadence mode we estimate that TESS will find 1250+/-70 exoplanets (90% confidence), including 250 smaller than 2 Earth-radii. Furthermore, we predict an additional 3100 planets will be found in full-frame image data orbiting bright dwarf stars and more than 10,000 around fainter stars. We predict that TESS will find 500 planets orbiting M-dwarfs, but the majority of planets will orbit stars larger than the Sun. Our simulated sample of planets contains hundreds of small planets amenable to radial velocity follow-up, potentially more than tripling the number of planets smaller than 4 Earth-radii with mass measurements. This sample of simulated planets is available for use in planning follow-up observations and analyses.

• The paper revises TESS exoplanet yield estimates by analyzing CTL data to predict approximately 4,373 detections.
• It applies strict detection criteria—requiring a signal-to-noise ratio of 10 and minimum three transits—to forecast 1,293 detections in 2-minute cadence data.
• The study highlights key populations, including 238 super-Earths and 69 habitable zone candidates, which are ideal for radial velocity and spectroscopic follow-up.

A Revised Exoplanet Yield from the Transiting Exoplanet Survey Satellite (TESS)

In "A Revised Exoplanet Yield from the Transiting Exoplanet Survey Satellite (TESS)," Barclay et al. present updated forecasts concerning the number and characteristics of exoplanets expected to be discovered by TESS. While prior studies leveraged Galactic models and assumed populations, this analysis revises those estimates utilizing the TESS Input Catalog Candidate Target List, offering a more refined prognosis.

The authors estimate that TESS will identify approximately 4,373 exoplanets orbiting stars cataloged in the CTL, with around 1,293 of those detections occurring in the 2-minute cadence data. Notably, 238 of these are projected to be super-Earths (1.25-2.0 Earth-radii), while nearly 2,222 will be giant planets. Importantly, over 2100 planets smaller than 4 Earth-radii could be ascertained, rendering this data particularly valuable for obtaining mass measurements via radial velocity follow-up.

A strategic focus of TESS is locating planets around bright stars, thus facilitating subsequent characterization efforts. The authors predict most TESS discoveries will orbit stars brighter than those found by Kepler, enhancing the potential for spectroscopic studies. The forecast further includes 250 planets smaller than 2 Earth-radii among the 2-minute cadence targets, significantly enriching the pool of terrestrial-like planets available for detailed investigation.

Implications extend to the identification of habitable zone planets, with the paper predicting 69 potential candidates in this region, all orbiting M-dwarfs. Such findings are promising for future atmospheric studies, particularly with forthcoming observational capabilities like those of the James Webb Space Telescope (JWST).

The revised estimates incorporated conservative modeling assumptions, such as requiring a signal-to-noise ratio of at least 10 and a minimum of three transits for detection, reducing the prospective yield to 2,609 planets in a more restricted scenario. These conservative assumptions underscore the uncertainty inherent in early-stage mission planning and projections, yet they provide a robust baseline for future observational strategies.

The paper highlights the increased potential for TESS to contribute significantly to the pool of small planets with mass measurements. This effort will complement existing surveys and expand the catalog of well-characterized exoplanets, marking a substantial advancement in exoplanetary science.

Overall, Barclay et al. provide a comprehensive revision of TESS's expected exoplanet yield, drawing on a more informed basis that aligns observational strategies with the scientific communities' priorities for follow-up and characterization. As TESS observations proceed, these predictions will be evaluated and refined, aiding in the strategic deployment of observational resources and furthering our understanding of planetary systems beyond our own.