HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES

“These coefficients were later replaced (Mischna et al. 2000) by coefficients generated using the correlated-k technique (Mlawer et al. 1997; Kato et al. 1999).”

“Rayleigh scattering by water was also considered by Kasting (1988); Kasting et al. (1993), but these authors used the scattering coefficient for air because the coefficient for H2O was not available, or at least not known to them.”

“It is a program to produce high-resolution spectrum of any gas mixture, in any thermodynamical conditions, from line-by-line (LBL) databases such as HITRAN 2008 (Rothman et al. 2009) and HITEMP 20104 (Rothman et al. 2010).”

“As with the inner edge model, a more optimistic empirical limit on the OHZ can be estimated based on the observation that early Mars was warm enough for liquid water to flow on its surface (Pollack et al. 1987; Bibring et al. 2006).”

“Estimates of luminosities will be derived using photometric and spectroscopic distances for now (in cases where parallax measurements are absent), but eventually GAIA (Perryman et al. 2001) will yield very precise parallaxes (and by extension precise luminosities) for all these target stars.”

“In order to assess the potential habitability of recently discovered exoplanets, equilibrium temperature (Teq) has been used as a metric (Borucki et al. 2011; Batalha et al. 2012).”

“A δ two-stream approximation (Toon et al. 1989) was used to calculate the net absorbed solar radiation for each of the 101 layers, using separate eight-term, correlated-k coefficients for both CO2 and H2O to parameterize absorption in each of the 38 solar spectral intervals ranging from 0.2− 4.5µm.”

“(1) in Gough (1981) and Table 2 in Bahcall et al. (2001)).”

“Formation of dynamically stable terrestrial planets in the HZs of multiple star systems has been studied before (Whitmire et al. 1998; Holman & Wiegert 1999; Haghighipour & Raymond 2007) and several studies estimated HZ boundaries around these types of systems (Eggl et al. 2012a,b; Kane & Hinkel…”

“4.37 of Pierrehumbert (2010) for a planet saturated with pure water vapor atmosphere and with a surface gravity of 10ms−2.”

“Recent discoveries by both the Kepler mission and RV surveys have shown that planets can exist in stable orbits around multiple star systems (Doyle et al. 2011; Welsh et al. 2012; Orosz et al. 2012; Dumusque et al. 2012).”

“Rayleigh scattering by water was also considered by Kasting (1988); Kasting et al. (1993), but these authors used the scattering coefficient for air because the coefficient for H2O was not available, or at least not known to them.”

“Previous climate model calculations by our group and others (Kasting et al. 1984; Pollack et al. 1987; Kasting 1991; Forget & Pierrehumbert 1997; Mischna et al. 2000) parametrized collision-induced absorption (CIA) by CO2 near 7 µm and beyond 20 µm by the formulation given in the Appendix of…”

“Several other studies (Underwood et al. 2003; Selsis et al. 2007b) parameterized these results to estimate relationships between HZ boundaries and stellar parameters for stars of different spectral types.”

“The orbital parameters of the planets and stellar characteristics were obtained from exoplanets.org (Wright et al. 2011).”

“Previous climate model calculations by our group and others (Kasting et al. 1984; Pollack et al. 1987; Kasting 1991; Forget & Pierrehumbert 1997; Mischna et al. 2000) parametrized collision-induced absorption (CIA) by CO2 near 7 µm and beyond 20 µm by the formulation given in the Appendix of…”

“Recent discoveries by both the Kepler mission and RV surveys have shown that planets can exist in stable orbits around multiple star systems (Doyle et al. 2011; Welsh et al. 2012; Orosz et al. 2012; Dumusque et al. 2012).”

“Several potential HZ planet candidates have already been detected, (Udry et al. 2007; Pepe et al. 2011a; Borucki et al. 2011; Bonfils et al. 2011; Borucki et al. 2012; Vogt et al. 2012; Tuomi et al. 2012a,b) and it is expected that this number will greatly increase as time passes (Batalha et al.…”

“We have also estimated HZ boundaries for M stars with Teff as low as 2600 K, which are primary targets for ongoing surveys such as Habitable Zone Planet Finder and MEARTH to discover potential habitable planets.”

“Previous climate model calculations by our group and others (Kasting et al. 1984; Pollack et al. 1987; Kasting 1991; Forget & Pierrehumbert 1997; Mischna et al. 2000) parametrized collision-induced absorption (CIA) by CO2 near 7 µm and beyond 20 µm by the formulation given in the Appendix of…”

“Recent discoveries by both the Kepler mission and RV surveys have shown that planets can exist in stable orbits around multiple star systems (Doyle et al. 2011; Welsh et al. 2012; Orosz et al. 2012; Dumusque et al. 2012).”

“At larger pCO2 values the increase in surface pressure outstrips the increase in the saturation vapor pressure of water, so the atmosphere becomes more stable against water loss (Kasting & Ackerman 1986).”

“– 31 – Previous work has shown that such planets may indeed be habitable (Joshi et al. 1997; Joshi 2003; Edson et al. 2003); however, systematic exploration of synchronously rotating planets in different parts of the HZ has not been attempted.”

“Recent discoveries by both the Kepler mission and RV surveys have shown that planets can exist in stable orbits around multiple star systems (Doyle et al. 2011; Welsh et al. 2012; Orosz et al. 2012; Dumusque et al. 2012).”

“D line-by-line radiative transfer model SMART (Spectral Mapping Atmospheric Radiative Transfer) developed by D. Crisp (Meadows & Crisp 1996; Crisp 1997).”

“…defined as the circumstellar region in which a terrestrial-mass planet with a CO2-H2O-N2 atmosphere can sustain liquid water on its surface 2 (Huang 1959; Hart 1978; Kasting et al. 1993; Underwood et al. 2003; Selsis et al. 2007b; Kaltenegger et al. 2011b; Pierrehumbert & Gaidos 2011).”

“These coefficients were later replaced (Mischna et al. 2000) by coefficients generated using the correlated-k technique (Mlawer et al. 1997; Kato et al. 1999).”

“It should be acknowledged that some authors (e.g., Segura et al. (2002, 2008)) do not agree that early Mars must have been warm; however, in our view, these cold early Mars models do not produce enough rainfall to explain valley formation (Ramirez et al. 2012a).”

“We have included a ‘?’ for Gl 581 system of planets in the plot, indicating that there is an active ongoing discussion in the literature about the number of planets in this system and their exact orbital parameters (Vogt et al. 2010; Pepe et al. 2011b; Vogt et al. 2012; Baluev 2012).”

“We anticipate having this information for ∼ 650 M dwarfs drawn from the J 10 Lepine & Gaidos (2011)catalog, and have applied for time to observe ∼ 300 more.”

“Experimental evidence indicates that the absorption by CO2 is overestimated if Lorentzian line shapes are used (Burch et al. 1969; Fukabori et al. 1986; Bezard et al. 1990; Halevy et al. 2009).”

“Several potential HZ planet candidates have already been detected, (Udry et al. 2007; Pepe et al. 2011a; Borucki et al. 2011; Bonfils et al. 2011; Borucki et al. 2012; Vogt et al. 2012; Tuomi et al. 2012a,b) and it is expected that this number will greatly increase as time passes (Batalha et al.…”

“NASA’s James Webb Space Telescope (JWST), scheduled to launch in 2018, is considered to be marginally capable of obtaining a transit spectrum of an Earth-like planet orbiting a late M dwarf (Clampin et al. 2007; Kaltengger & Traub 2009; Deming et al. 2009).”

“…emission spectra of Earth-like planets in a 1D model (Kitzmann et al. 2011a,b), while others studied the habitability of specific systems, particularly Gl 581, in 1D (Wordsworth et al. 2010; Von Paris et al. 2011a; Kaltenegger et al. 2011a) and 3D (Wordsworth et al. 2011; Pierrehumbert 2011).”

“Several other surveys are either underway (Nutzman & Charbonneau 2008, MEARTH) or getting ready to be commissioned (Mahadevan et al. 2012, HPF) in an attempt to discover rocky planets in the HZs of low mass stars.”

“Experimental evidence indicates that the absorption by CO2 is overestimated if Lorentzian line shapes are used (Burch et al. 1969; Fukabori et al. 1986; Bezard et al. 1990; Halevy et al. 2009).”

“…emission spectra of Earth-like planets in a 1D model (Kitzmann et al. 2011a,b), while others studied the habitability of specific systems, particularly Gl 581, in 1D (Wordsworth et al. 2010; Von Paris et al. 2011a; Kaltenegger et al. 2011a) and 3D (Wordsworth et al. 2011; Pierrehumbert 2011).”

“Furthermore, the coefficients adopted by Mischna et al. (2000) and used in subsequent climate modeling studies by the Kasting research group were obtained using HITRAN 1996 database and had not been updated since then.”

“We have included a ‘?’ for Gl 581 system of planets in the plot, indicating that there is an active ongoing discussion in the literature about the number of planets in this system and their exact orbital parameters (Vogt et al. 2010; Pepe et al. 2011b; Vogt et al. 2012; Baluev 2012).”

“We have included a ‘?’ for Gl 581 system of planets in the plot, indicating that there is an active ongoing discussion in the literature about the number of planets in this system and their exact orbital parameters (Vogt et al. 2010; Pepe et al. 2011b; Vogt et al. 2012; Baluev 2012).”

“Wordsworth et al. (2010) used 22 layers in their model, compared to 70 layers in our SMART comparison climate models.”

“Therefore, we used the prescription of Perrin & Hartmann (1989) for ‘subLorentzian’ absorption in the far wings of the lines when running KSPECTRUM.”

“It should be acknowledged that some authors (e.g., Segura et al. (2002, 2008)) do not agree that early Mars must have been warm; however, in our view, these cold early Mars models do not produce enough rainfall to explain valley formation (Ramirez et al. 2012a).”

“Dense CO2 atmosphere Dense CO2-rich atmospheres have been suggested as warming agents for early Mars (Pollack et al. 1987; Kasting 1991; Forget & Pierrehumbert 1997; Tian et al. 2010).”

“Several other studies (Underwood et al. 2003; Selsis et al. 2007b) parameterized these results to estimate relationships between HZ boundaries and stellar parameters for stars of different spectral types.”

“Formation of dynamically stable terrestrial planets in the HZs of multiple star systems has been studied before (Whitmire et al. 1998; Holman & Wiegert 1999; Haghighipour & Raymond 2007) and several studies estimated HZ boundaries around these types of systems (Eggl et al. 2012a,b; Kane & Hinkel…”

“Ongoing work by our team (Terrien et al. 2012) is yielding low resolution NIR spectra from the infrared Telelescope Facility (IRTF) to be used to derive stellar metallicities as well as yielding more realistic flux distributions and temperatures for use in the modeling.”

“These values were based either on the Kasting et al. (1993) model (Traub 2012) or the Selsis et al. (2007b) results (Bonfils et al. 2011).”

“In our model we have updated CO2-CIA using the parametrization described in Gruszka & Borysow (1997); Baranov et al. (2004); Halevy et al. (2009).”

“The following expression for the scattering crosssection was adopted (Allen 1976; Vardavas & Carver 1984; Von Paris et al. 2010): σR,H2O(λ) = 4.577× 10 −21 (6 + 3D 6− 7D )( r2 λ4 ) cm2 (1) Here, D is the depolarization ratio (0.17 for H2O, Marshall & Smith (1990)), r is the wavelength (λ)-dependent…”

“It has been argued that this methodology tends to overestimate the greenhouse effect of dense CO2 atmospheres (Goldblatt & Zahnle 2011).”

“…of dynamically stable terrestrial planets in the HZs of multiple star systems has been studied before (Whitmire et al. 1998; Holman & Wiegert 1999; Haghighipour & Raymond 2007) and several studies estimated HZ boundaries around these types of systems (Eggl et al. 2012a,b; Kane & Hinkel 2012)…”

“The solar constant is assumed to be 75% of its present value (1360 Wm−2), matching the solar flux incident on early Mars (3.8 Gyr).”

“…planets in the HZs of multiple star systems has been studied before (Whitmire et al. 1998; Holman & Wiegert 1999; Haghighipour & Raymond 2007) and several studies estimated HZ boundaries around these types of systems (Eggl et al. 2012a,b; Kane & Hinkel 2012) using Kasting et al. (1993) model.”

“D climate modeling studies include partial cloud coverage (Selsis et al. 2007b) and/or parameterized microphysical cloud model (Colaprete & Toon 2003; Zsom et al. 2012), but we do not consider them here because we can not model them self-consistently in our model.”

“The corresponding continuum absorption is therefore ‘super-Lorenztian’ for H2O, and we have used the ‘BPS’ formalism of Paynter & Ramaswamy (2011) to parameterize this absorption.”

“Experimental evidence indicates that the absorption by CO2 is overestimated if Lorentzian line shapes are used (Burch et al. 1969; Fukabori et al. 1986; Bezard et al. 1990; Halevy et al. 2009).”

“…emission spectra of Earth-like planets in a 1D model (Kitzmann et al. 2011a,b), while others studied the habitability of specific systems, particularly Gl 581, in 1D (Wordsworth et al. 2010; Von Paris et al. 2011a; Kaltenegger et al. 2011a) and 3D (Wordsworth et al. 2011; Pierrehumbert 2011).”

“Some studies have investigated the effects of clouds on planetary emission spectra of Earth-like planets in a 1D model (Kitzmann et al. 2011a,b), while others studied the habitability of specific systems, particularly Gl 581, in 1D (Wordsworth et al. 2010; Von Paris et al. 2011a; Kaltenegger et al.…”

“(Teff <= 4000 K) comes from the fact that planets within the HZs of these stars are expected to be tidally locked (Dole 1964; Peale 1977; Kasting et al. 1993; Dobrovolskis 2009).”

“Experimental evidence indicates that the absorption by CO2 is overestimated if Lorentzian line shapes are used (Burch et al. 1969; Fukabori et al. 1986; Bezard et al. 1990; Halevy et al. 2009).”

“…IRTF data, and also 9http://perso.ens-lyon.fr/france.allard/ high-resolution CRIRES data on Barnard’s star (from the CRIRES POP library10 (Lebzelter et al. 2012)), show that the models are quite good in reproducing the gross spectral features and energy distributions of stars, and will…”

“Some studies have investigated the effects of clouds on planetary emission spectra of Earth-like planets in a 1D model (Kitzmann et al. 2011a,b), while others studied the habitability of specific systems, particularly Gl 581, in 1D (Wordsworth et al. 2010; Von Paris et al. 2011a; Kaltenegger et al.…”

“Some studies have investigated the effects of clouds on planetary emission spectra of Earth-like planets in a 1D model (Kitzmann et al. 2011a,b), while others studied the habitability of specific systems, particularly Gl 581, in 1D (Wordsworth et al. 2010; Von Paris et al. 2011a; Kaltenegger et al.…”

“The following expression for the scattering crosssection was adopted (Allen 1976; Vardavas & Carver 1984; Von Paris et al. 2010): σR,H2O(λ) = 4.577× 10 −21 (6 + 3D 6− 7D )( r2 λ4 ) cm2 (1) Here, D is the depolarization ratio (0.17 for H2O, Marshall & Smith (1990)), r is the wavelength (λ)-dependent refractivity which…”

“In the most conservative case, we adopt the maximum greenhouse (Max GH) and moist greenhouse (Moist GH) insolation limits from Kopparapu et al. (2013b).”

“Pierrehumbert and Gaidos (18) estimated that the outer edge of the HZ may extend up to 10 AU for planets that are kept warm by efficient greenhouse warming with an H2 atmosphere.”