EXPLORING THE HABITABLE ZONE FOR
                    <i>KEPLER</i>
                    PLANETARY CANDIDATES

Kaltenegger, Lisa; Sasselov, Dimitar

doi:10.1088/2041-8205/736/2/l25

Cited by 103 publications

(121 citation statements)

References 30 publications

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“…Considering the case where the whole planetary surface re-radiates the absorbed flux (e.g., β factor of Kaltenegger & Sasselov (2011) equal to 1), the equilibrium temperature of GJ 163c is…”

Section: Gl163c In the Habitable Zone?mentioning

confidence: 99%

“…An albedo greater than 0.34 is, however, possible if 40-50% of the atmosphere is covered by clouds (see, for example, Fig. 1 of Kaltenegger & Sasselov 2011). The precise location of GJ 163c with respect to the habitable zone may further depend on additional heating such as tidal (Barnes et al 2012) or radiogenic (Ehrenreich et al 2006) heatings, and more detailed studies are thus welcome.…”

Section: Gl163c In the Habitable Zone?mentioning

confidence: 99%

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The HARPS search for southern extra-solar planets

Bonfils

Curto

Correia

et al. 2013

A&A

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The meter-per-second precision achieved by today's velocimeters enables us to search for 1−10 M ⊕ planets in the habitable zone of cool stars. This paper reports on the detection of three planets orbiting GJ 163 (HIP 19394), a M3 dwarf monitored by our ESO/HARPS search for planets. We made use of the HARPS spectrograph to collect 150 radial velocities of GJ 163 over a period of eight years. We searched the radial-velocity time series for coherent signals and found five distinct periodic variabilities. We investigated the stellar activity and called into question the planetary interpretation for two signals. Before more data can be acquired we concluded that at least three planets are orbiting GJ 163. They have orbital periods of P b = 8.632 ± 0.002, P c = 25.63 ± 0.03, and P d = 604 ± 8 days and minimum masses m sin i = 10.6 ± 0.6, 6.8 ± 0.9, and 29 ± 3 M ⊕ , respectively. We hold our interpretations for the two additional signals with periods P (e) = 19.4 and P ( f ) = 108 days. The inner pair presents an orbital period ratio of 2.97, but a dynamical analysis of the system shows that it lays outside the 3:1 mean motion resonance. The planet GJ 163c, in particular, is a super-Earth with an equilibrium temperature of T eq = (302 ± 10)(1 − A) 1/4 K and may lie in the so-called habitable zone for albedo values (A = 0.34−0.89) moderately higher than that of Earth (A ⊕ = 0.2−0.3).

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Section: Gl163c In the Habitable Zone?mentioning

confidence: 99%

Section: Gl163c In the Habitable Zone?mentioning

confidence: 99%

The HARPS search for southern extra-solar planets

Bonfils

Curto

Correia

et al. 2013

A&A

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“…Under this hypothesis, equating the stellar fluxes absorbed and radiated by the planet (see e.g. Kaltenegger & Sasselov 2011, for details of the computation), Eq. (1) can be rewritten as…”

Section: Methodsmentioning

confidence: 99%

Evolution of the habitable zone of low-mass stars

Valle

Dell’Omodarme

Moroni

et al. 2014

A&A

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Context. The habitability of an exoplanet is assessed by determining the times at which its orbit lies in the circumstellar habitable zone (HZ). This zone evolves with time following the stellar luminosity variation, which means that the time spent in the HZ depends on the evolution of the host star. Aims. We study the temporal evolution of the HZ of low-mass stars -only due to stellar evolution -and evaluate the related uncertainties. These uncertainties are then compared with those due to the adoption of different climate models. Methods. We computed stellar evolutionary tracks from the pre-main sequence phase to the helium flash at the red-giant branch tip for stars with masses in the range [0.70−1.10] M , metallicity Z in the range [0.005−0.04], and various initial helium contents. By adopting a reference scenario for the HZ computations, we evaluated several characteristics of the HZ, such as the distance from the host star at which the habitability is longest, the duration of this habitability, the width of the zone for which the habitability lasts one half of the maximum, and the boundaries of the continuously habitable zone (CHZ) for which the habitability lasts at least 4 Gyr. We developed analytical models, accurate to the percent level or lower, which allowed to obtain these characteristics in dependence on the mass and the chemical composition of the host star. Results. The metallicity of the host star plays a relevant role in determining the HZ. The importance of the initial helium content is evaluated here for the first time; it accounts for a variation of the CHZ boundaries as large as 30% and 10% in the inner and outer border. The computed analytical models allow the first systematic study of the variability of the CHZ boundaries that is caused by the uncertainty in the estimated values of mass and metallicity of the host star. An uncertainty range of about 30% in the inner boundary and 15% in the outer one were found. We also verified that these uncertainties are larger than that due to relying on recently revised climatic models, which leads to a CHZ boundary shift within ±5% with respect to those of our reference scenario. We made an on-line tool available that provides both HZ characteristics and interpolated stellar tracks.

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“…Kasting, Whitmire & Reynolds 1993, Kaltenegger & Sasselov 2011. This makes the definition of the HZ a highly interdisciplinary topic, including e.g.…”

Section: Introductionmentioning

confidence: 99%

On the Possibility of Habitable Trojan Planets in Binary Star Systems

Schwarz

Funk

Bazsó

2015

Orig Life Evol Biosph

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Abstr actApproximately 60 percent of all stars in the solar neighbourhood (up to 80 percent in our Milky Way) are members of binary or multiple star systems. This fact led to the speculations that many more planets may exist in binary systems than are currently known. To estimate the habitability of exoplanetary systems, we have to define the so-called habitable zone (HZ). The HZ is defined as a region around a star where a planet would receive enough radiation to maintain liquid water on its surface and to be able to build a stable atmosphere. We search for new dynamical configurations -where planets may stay in stable orbits -to increase the probability to find a planet like the Earth. Therefore we investigated five candidates and found that two systems (HD 41004 and HD 196885) which have small stable regions. Intr oductionToday we know about 3000 exoplanets thereof 100 exoplanets are found in binary star systems and approximately 20 exoplanets in multiple (triple) star systems. The data and statistics of all planets are collected in the Exoplanet-catalogue maintained by J. Schneider 1 at (see Schneider et al. 2011) whereas the binary-and multiple-star systems can be found at binary catalogue of exoplanets maintained by R. Schwarz 2 1 (see Schwarz et al. 2016).http://exoplanet.eu 2 http://www.univie.ac.at/adg/schwarz/multiple.html When we speak about the possibility of habitable Trojan planets in binary star systems we have to answer two questions:• Why do we sear ch for exoplanets in binar ies? Because many stars in the solar Neighbourhood are members of binary or multiple star systems. This fact leads to the conclusion that the knowledge of the dynamics of exoplanets in binary systems will be important in the future.• Why do we sear ch for Tr ojan planets? Because we are searching for new dynamical configurations where planets may stay in stable orbits. The more planets we will find the higher the possibility will be, to find a planet like the EARTH! Fig. 1 Dependence of the secondary star mass m2 on the mass ratio μ and the mass of the primary star m1 (main sequence stars between 0.5 < Msun < 3).Jupiter's Trojan asteroids are in a 1:1 mean motion resonance with Jupiter, librating around the L 4 or L 5 points of the Sun-Jupiter system, preceding (L 4 ) or following (L 5 ) Jupiter at about 60°. Today we know approximately 5100 Jovian, 8 Neptunian and 5 Martian Trojans, but also one Uranus Trojan (2011QF99) and one Earth Trojan (2010TK7) were found.It is known that in the planar, circular restricted three-body problem the equilibrium points L 4 or L 5 are stable for mass ratios up to μ = 0.04; this stability limit is marked in Fig.1 as dashed vertical line. The mass ratio μ is defined as μ = m 2 / (m 1 + m 2 ) at which m 1 and m 2 being the masses of the primary and secondary bodies. So it seems that binaries may not have a population of Trojan asteroids or a Trojan planet, because the masses of the stars involved are comparable. However in a former study (Schwarz et al. 2009) we could show that binaries can ...

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EXPLORING THE HABITABLE ZONE FOR KEPLER PLANETARY CANDIDATES

Cited by 103 publications

References 30 publications

The HARPS search for southern extra-solar planets

The HARPS search for southern extra-solar planets

Evolution of the habitable zone of low-mass stars

On the Possibility of Habitable Trojan Planets in Binary Star Systems

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