Detectability of Earth-like Planets in Multi-Planet Systems: Preliminary Report

Traub, Wesley A.; Beichman, Charles; Boden, Andrew F.; Boss, Alan P.; Casertano, Stefano; Catanzarite, J.; Fischer, Debra A.; Ford, Eric B.; Gould, A.; Halverson, Samuel; Howard, Andrew W.; Ida, Shigeru; Kasdin, N. Jeremy; Laughlin, Gregory; Levison, Harold F.; Lin, D. C.; Макаров, В. В.; Marr, James C.; Muterspaugh, Matthew W.; Raymond, Sean N.; Savransky, Dmitry; Shao, M.; Sozzetti, A.; Zhai, Chengxing

doi:10.1051/eas/1042022

Cited by 45 publications

(16 citation statements)

References 3 publications

(4 reference statements)

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“…The dominant factor will rather be the instrumental precision. Note that if present, other larger planets will also induce noise, which is not considered in this paper, but the series of blind tests conducted to estimate the detection capabilities of Earth-like planets in multiple systems by space-borne astrometry (Traub et al 2010) have shown that this noise can be well circumvented.…”

Section: Planet Detection In Astrometrymentioning

confidence: 99%

Using the Sun to estimate Earth-like planets detection capabilities

Lagrange

Meunier

Desort

et al. 2011

A&A

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Aims. Stellar activity is a potentially important limitation to the detection of low-mass extrasolar planets with indirect methods (radial velocity, photometry, astrometry). In previous papers, using the Sun as a proxy, we investigated the impact of stellar activity (spots, plages, convection) on the detectability of an Earth-mass planet in the habitable zone (HZ) of solar-type stars with radial velocity techniques. We here extend the detectability study to astrometry. Methods. We used the sunspot and plages properties recorded over one solar cycle to infer the astrometric variations that a Sun-like star seen edge-on, 10 pc away, would exhibit, if covered by such spots/bright structures. We compare the signal to the one expected from the astrometric wobble (0.3 µas) of such a star surrounded by a one Earth-mass planet in the HZ. We also briefly investigate higher levels of activity. Results. The activity-induced astrometric signal along the equatorial plane has an amplitude of typically less than 0.2 µas (rms = 0.07 µas), lower than the one expected from an Earth-mass planet at 1 AU. Hence, for this level of activity, the detectability is governed by the instrumental precision rather than the activity. We show that for instance a one Earth-mass planet at 1 AU would be detected with a monthly visit during less than five years and an instrumental precision of 0.8 µas. A level of activity five times higher would still allow this detection with a precision of 0.35 µas. We conclude that astrometry is an attractive approach to search for such planets around solar type stars with most levels of stellar activity.

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Section: Planet Detection In Astrometrymentioning

confidence: 99%

Using the Sun to estimate Earth-like planets detection capabilities

Lagrange

Meunier

Desort

et al. 2011

A&A

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“…NASA conducted a double blind study for the astrometric detection of Earth-like planets in multiple planet systems (Traub et al 2010). The result of the test was that the presence of multiple planets has a marginal to negligible impact on the astrometric mission's ability to detect and measure the orbits of terrestrial planets (planets of mass 1 to 10 M ⊕ ) in the HZ.…”

Section: Astrometric Orbit Precisionmentioning

confidence: 99%

“…Core accretion models predict a peak in the planet population near 10-30 M ⊕ composed of planets that did not manage to reach the stage of runaway gas accretion (Mordasini et al 2009). For an astrometric mission such as SIM Lite, it is not significantly harder to find an exo-Earth in a multiple planet system than it would be if the exo-Earth were alone (Traub et al 2010). Current studies of direct imaging missions do not address the problem of confusion due to multiple planets (Brown 2005;Savransky et al 2009aSavransky et al , 2009bSavransky et al , 2010.…”

Section: Modeling Realistic Planet Systemsmentioning

confidence: 99%

“…But some types of coronagraphs are seriously limited in their ability to take images at many epochs. Recent studies have shown that an astrometric mission will have a completeness for detection of 95% for star-planet systems within 10 pc of the Sun (Traub et al 2010). On the other hand, the completeness for detection for a direct imaging mission, in the absence of data from an astrometric mission, has been shown to be 35% (Savransky et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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The Synergy of Direct Imaging and Astrometry for Orbit Determination of Exo-Earths

Shao

Catanzarite

Pan

2010

ApJ

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The holy grail of exoplanet searches is an exo-Earth, an Earth mass planet in the habitable zone (HZ) around a nearby star. Mass is one of the most important characteristics of a planet and can only be measured by observing the motion of the star around the planet-star center of gravity. The planet's orbit can be measured either by imaging the planet at multiple epochs or by measuring the position of the star at multiple epochs by space-based astrometry. The measurement of an exoplanet's orbit by direct imaging is complicated by a number of factors. One is the inner working angle (IWA). A space coronagraph or interferometer imaging an exo-Earth can separate the light from the planet from the light from the star only when the star-planet separation is larger than the IWA. Second, the apparent brightness of a planet depends on the orbital phase. A single image of a planet cannot tell us whether the planet is in the HZ or distinguish whether it is an exo-Earth or a Neptune-mass planet. Third is the confusion that may arise from the presence of multiple planets. With two images of a multiple planet system, it is not possible to assign a dot to a planet based only on the photometry and color of the planet. Finally, the planet-star contrast must exceed a certain minimum value in order for the planet to be detected. The planet may be unobservable even when it is outside the IWA, such as when the bright side of the planet is facing away from us in a "crescent" phase. In this paper we address the question: "Can a prior astrometric mission that can identify which stars have Earth-like planets significantly improve the science yield of a mission to image exoEarths?" In the case of the Occulting Ozone Observatory, a small external occulter mission that cannot measure spectra, we find that the occulter mission could confirm the orbits of ∼4 to ∼5 times as many exo-Earths if an astrometric mission preceded it to identify which stars had such planets. In the case of an internal coronagraph we find that a survey of the nearest ∼60 stars could be done with a telescope half the size if an astrometric mission had first identified the presence of Earth-like planets in the HZ and measured their orbital parameters.

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“…Thanks to the increased sensitivity of instruments, astronomers have found that there are many more small exoplanets than giant, gaseous ones. According to recent estimates, [1][2][3][4][5] there are at least 10% of stars that would have a small planet orbiting in their habitable zone (HZ).…”

Section: Introductionmentioning

confidence: 99%

NEAT: ultra-precise differential astrometry to characterize planetary systems with Earth-mass exoplanets in the vicinity of our Sun

Malbet¹,

Crouzier

Léger

et al. 2014

SPIE Proceedings

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The nearest solar-type stars are of prime interest for the science of exoplanets because they are the objects most suitable for direct detection and future spectroscopic investigations. Astrometry combined with radial velocity is the technique that can reveal planets with mass as small as the Earth mass in the 1 AU domain. We present in this contribution the result of a 3-year study on a mission capable to perform ultra-precise differential astrometry called NEAT (Nearby Earth Astrometric Telescope) and characterize planetary systems with Earthmass exoplanets in the vicinity of our Sun. This mission requires exquisite calibration of the focal plane together with innovative approaches to obtain a very stable long focal telescope. This mission will be submitted in 2014 to the ESA M4 Call for Mission.

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Detectability of Earth-like Planets in Multi-Planet Systems: Preliminary Report

Abstract: We ask if Earth-like planets (terrestrial mass and habitable-zone orbit) can be detected in multi-planet systems, using astrometric and radial velocity observations. We report here the preliminary results of double-blind calculations designed to answer this question.

Cited by 45 publications

References 3 publications

Using the Sun to estimate Earth-like planets detection capabilities

Using the Sun to estimate Earth-like planets detection capabilities

The Synergy of Direct Imaging and Astrometry for Orbit Determination of Exo-Earths

NEAT: ultra-precise differential astrometry to characterize planetary systems with Earth-mass exoplanets in the vicinity of our Sun

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