Exo-Earth/Super-Earth Yield of JWST Plus a Starshade External Occulter

Catanzarite, J.; Shao, Michael

doi:10.1086/658243

Cited by 27 publications

(4 citation statements)

References 19 publications

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“…is a key parameter for planning future space missions to directly image and measure the spectra of exo-Earths. Many mission concepts that have been studied could potentially succeed only if is large, at least 20% (Savransky, Kasdin, & Cady, 2010); (Catanzarite & Shao, 2011). A significantly smaller value of means that a mission to detect nearby Earths would have to be capable of searching 100 or more of the nearest stars instead of 10 or 15.…”

Section: Discussionmentioning

confidence: 99%

The Occurrence Rate of Earth Analog Planets Orbiting Sun-Like Stars

Catanzarite

Shao

2011

ApJ

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114

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Kepler is a space telescope that searches Sun-like stars for planets. Its major goal is to determine , the fraction of Sunlike stars that have planets like Earth. When a planet 'transits' or moves in front of a star, Kepler can measure the concomitant dimming of the starlight. From analysis of the first four months of those measurements for over 150,000 stars, Kepler's science team has determined sizes, surface temperatures, orbit sizes and periods for over a thousand new planet candidates. In this paper, we characterize the period probability distribution function of the super-Earth and Neptune planet candidates with periods up to 132 days, and find three distinct period regimes. For candidates with periods below 3 days the density increases sharply with increasing period; for periods between 3 and 30 days the density rises more gradually with increasing period, and for periods longer than 30 days, the density drops gradually with increasing period. We estimate that 1% to 3% of stars like the Sun are expected to have Earth analog planets, based on the Kepler data release of Feb 2011. This estimate of is based on extrapolation from a fiducial subsample of the Kepler planet candidates that we chose to be nominally 'complete' (i.e., no missed detections) to the realm of the Earth-like planets, by means of simple power law models. The accuracy of the extrapolation will improve as more data from the Kepler mission is folded in. Accurate knowledge of is essential for the planning of future missions that will image and take spectra of Earthlike planets. Our result that Earths are relatively scarce means that a substantial effort will be needed to identify suitable target stars prior to these future missions. Selection criteria for the sample of transiting planet candidatesThe February 2011 Kepler data release contains 1235 candidate planets detected in the first ~4 months of science operations (Borucki, 2011). If a transit was detected during the first 132 days, all subsequent transits over the period Q0 -Q5 (about 400 days) were also used to refine the transit parameters included in the data release. Therefore detections of transiting planets with periods shorter than 132 days are complete as long as transit duration and depth provide sufficient SNR. Following the practice of the Kepler Science Team, we exclude the 17 planet candidates whose radius exceeds twice that of Jupiter as they are likely to be grazing binary companions. We also exclude candidates with a single observed transit (over the Kepler mission from Q0 -Q5) as these have a high likelihood of being false detections. Excluding the 33 candidates with both these attributes leaves 1202 transit candidates. The fiducial data set is nominally completeCorrection for completeness is essential when calculating the fraction of stars that have planets. Kepler doesn't detect any planets of radius 0.1 , but that doesn't mean they don't exist. We chose a fiducial sample with radii ranging from 2 to 4 and scaled semi-major axis ranging from 0.25 to 0.5 AU because the s...

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Section: Discussionmentioning

confidence: 99%

The Occurrence Rate of Earth Analog Planets Orbiting Sun-Like Stars

Catanzarite

Shao

2011

ApJ

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114

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“…The inventory of confirmed exoplanets provided by the NASA Exoplanet Archive (Akeson et al 2013), extracted 2020 May 11, indicates that planets more massive than 0.5 Jupiter masses orbiting stars less massive than 0.5 solar masses comprise less than 2% of the total RV exoplanet discoveries. The architecture, exoplanet detection sensitivity, and prevalence of HZ planets in M-dwarf systems clearly play significant roles in calculations of occurrence rates of HZ terrestrial planets (Catanzarite & Shao 2011;Dressing & Charbonneau 2013;Gaidos 2013;Kopparapu 2013;Foreman-Mackey et al 2014;Dressing & Charbonneau 2015). The dynamics and prevalence of HZ terrestrial planets have yet to be as rigorously tested around solar-type stars.…”

Section: Introductionmentioning

confidence: 99%

Dynamical Packing in the Habitable Zone: The Case of Beta CVn

Kane

Turnbull

Fulton

et al. 2020

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Uncovering the occurrence rate of terrestrial planets within the habitable zone (HZ) of their host stars has been a particular focus of exoplanetary science in recent years. The statistics of these occurrence rates have largely been derived from transiting planet discoveries, and have uncovered numerous HZ planets in compact systems around M-dwarf host stars. Here we explore the width of the HZ as a function of spectral type, and the dynamical constraints on the number of stable orbits within the HZ for a given star. We show that, although the Hill radius for a given planetary mass increases with larger semimajor axis, the width of the HZ for earlier-type stars allows for more terrestrial planets in the HZ than late-type stars. In general, dynamical constraints allow ∼6 HZ Earth-mass planets for stellar masses 0.7M e , depending on the presence of farther out giant planets. As an example, we consider the case of Beta CVn, a nearby bright solar-type star. We present 20 yr of radial velocities (RV) from the Keck/High Resolution Echelle Spectrometer (HIRES) and Automated Planet Finder (APF) instruments and conduct an injection-recovery analysis of planetary signatures in the data. Our analysis of these RV data rule out planets more massive than Saturn within 10 au of the star. These system properties are used to calculate the potential dynamical packing of terrestrial planets in the HZ and show that such nearby stellar targets could be particularly lucrative for HZ planet detection by direct imaging exoplanet missions.

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“…Rocky planets like the Earth are 10 9 to 10 10 dimmer, in the visible, than their host stars; even in the thermal IR, where the contrast is lower, the luminosity ratio is still on the order of 10 7 . This barrier is expected to be broken with the advent the space telescope JWST (Charbonneau & Deming, 2007, Catanzarite & Shao 2011, with thermal IR capability, due for launch in 2018, and the groundbased E-ELT (Pantin, Salmon & Charnoz 2010, ESO 2011, capable of achieving a contras of 1:10 9 at 0.1 arcseconds, could observe super-Earth planets around the closest stars at thermal IR. Since the method described in this work does not put constraints on the planet´s radius, it would apply to hypothetical super-Earths in eccentric orbits that these two observatories might discover, provided that such planets have thin atmospheres (10 4 < χ < 10 5 mol m -2 ).…”

Section: Discussionmentioning

confidence: 99%

The most common habitable planets – atmospheric characterization of the subgroup of fast rotators

Pinotti¹

2013

Monthly Notices of the Royal Astronomical Society

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The current search for habitable planets has focused on Earth-like conditions of mass, volatile content and orbit. However, rocky planets following eccentric orbits, and drier than the Earth, may be a more common phenomenon in the Universe. For the subgroup of fast rotators, it is suggested that their atmospheric thermal capacitance, subject to the radiative forcing of their parent stars, may provide researchers in the near future with a simple method for the determination of a robust lower limit of atmospheric thickness. This technique, together with the spectroscopic analysis of resolved planets from their stars, both allowed by planned space and ground-based observatories with thermal IR capabilities, would enable us with a better understanding of the habitability of this class of planets. The technique works better for smaller orbital periods, but since the tidal lock radius of M dwarfs encompasses their HZ, the optimum targets would be planets around K dwarf stars. The atmospheric thermal capacitance could also expand the range of Habitable Zones for shorter orbits, particularly for planets around M dwarf stars, since the higher frequency of the periodic radiative forcing dampens the surface temperature variation considerably.

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Exo-Earth/Super-Earth Yield of JWST Plus a Starshade External Occulter

Cited by 27 publications

References 19 publications

The Occurrence Rate of Earth Analog Planets Orbiting Sun-Like Stars

The Occurrence Rate of Earth Analog Planets Orbiting Sun-Like Stars

Dynamical Packing in the Habitable Zone: The Case of Beta CVn

The most common habitable planets – atmospheric characterization of the subgroup of fast rotators

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