ERRATUM: “HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES” (2013, ApJ, 765, 131)

Abstract

Identifying terrestrial planets in the habitable zones (HZs) of other stars is one of the primary goals of ongoing radial velocity (RV) and transit exoplanet surveys and proposed future space missions. Most current estimates of the boundaries of the HZ are based on one-dimensional (1D), cloud-free, climate model calculations by Kasting et al. However, this model used band models that were based on older HITRAN and HITEMP line-by-line databases. The inner edge of the HZ in the Kasting et al. model was determined by loss of water, and the outer edge was determined by the maximum greenhouse provided by a CO 2 atmosphere. A conservative estimate for the width of the HZ from this model in our solar system is 0.95-1.67 AU. Here an updated 1D radiative-convective, cloud-free climate model is used to obtain new estimates for HZ widths around F, G, K, and M stars. New H 2 O and CO 2 absorption coefficients, derived from the HITRAN 2008 and HITEMP 2010 line-by-line databases, are important improvements to the climate model. According to the new model, the water-loss (inner HZ) and maximum greenhouse (outer HZ) limits for our solar system are at 0.99 and 1.70 AU, respectively, suggesting that the present Earth lies near the inner edge. Additional calculations are performed for stars with effective temperatures between 2600 and 7200 K, and the results are presented in parametric form, making them easy to apply to actual stars. The new model indicates that, near the inner edge of the HZ, there is no clear distinction between runaway greenhouse and water-loss limits for stars with T eff 5000 K, which has implications for ongoing planet searches around K and M stars. To assess the potential habitability of extrasolar terrestrial planets, we propose using stellar flux incident on a planet rather than equilibrium temperature. This removes the dependence on planetary (Bond) albedo, which varies depending on the host star's spectral type. We suggest that conservative estimates of the HZ (water-loss and maximum greenhouse limits) should be used for current RV surveys and Kepler mission to obtain a lower limit on η ⊕ , so that future flagship missions like TPF-C and Darwin are not undersized. Our model does not include the radiative effects of clouds; thus, the actual HZ boundaries may extend further in both directions than the estimates just given.

Spectro-Thermometry of M Dwarfs and Their Candidate Planets: Too Hot, Too Cool, or Just Right?

“…We use the empirical relations described in Kopparapu et al (2013b), corrected in Kopparapu et al (2013a) and available in the accompanying online calculator. These calculations do not account for water clouds other than a decrease in the effective planetary albedo.…”

The SOPHIE search for northern extrasolar planets

“…This is done using Eqs. (2) and (3) of Kopparapu et al (2013b) and the erratum Kopparapu et al (2013a) for different habitable zone limits. They are listed in Table 5.…”

Stable habitable zones of single Jovian planet systems

“…One of the most exciting goals in astrophysics is the discovery of a true, twin Earth: a rocky planet of similar size, structure and composition to Earth on a stable orbit within its host star's habitable zone 1 (HZ) (Kasting et al 1993;Kopparapu et al 2013). As a result of biases inherent to observational techniques, the first exoplanets detected were often both massive and close to their host stars (e.g.…”