Design Considerations for a Ground-Based Transit Search for Habitable Planets Orbiting M Dwarfs

By P. Nutzman, D. Charbonneau. 2007

320 citations recorded by the source corpus.

By targeting nearby M dwarfs, a transit search using modest equipment is capable of discovering planets as small as 2 R⊕ in the habitable zones of their host stars. The MEarth Project, a future transit search, aims to employ a network of ground-based robotic telescopes to monitor M dwarfs in the northern hemisphere with sufficient precision and cadence to detect such planets. Here we investigate the design requirements for the MEarth Project. We evaluate the optimal bandpass, and the necessary field of view, telescope aperture, and telescope time allocation on a star-by-star basis, as is possible for the well-characterized nearby M dwarfs. Through these considerations, 1976 late M dwarfs (R < 0.33 R⊙) emerge as favorable targets for transit monitoring. Based on an observational cadence and on total telescope time allocation tailored to recover 90% of transit signals from planets in habitable zone orbits, we find that a network of 10 30 cm telescopes could survey these 1976 M dwarfs in less than three years. A null result from this survey would set an upper limit (at 99% confidence) of 17% for the rate of occurrence of planets larger than 2 R⊕ in the habitable zones of late M dwarfs, and even stronger constraints for planets lying closer than the habitable zone. If the true occurrence rate of habitable planets is 10%, the expected yield would be 2.6 planets.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/6618db177b6ff3bb4159af11cdc56d910bb0af2e

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Citations in the corpus

The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets (2017, methodology): “To determine the scale of the contribution, we calculated the range of radius and, by extension, density errors by integrating the contamination spectra presented in Section 3.2 over the Bessel I-band filter bandpass, which is similar to bandpasses used by ground-based transit surveys such as MEarth”
NEAR-INFRARED METALLICITIES, RADIAL VELOCITIES, AND SPECTRAL TYPES FOR 447 NEARBY M DWARFS (2013, methodology): “Nutzman & Charbonneau (2008) described how the MEarth targets were selected from the Lépine-Shara Proper Motion catalog of northern stars (LSPM-North; Lépine & Shara 2005).”
Stellar Flares from the First TESS Data Release: Exploring a New Sample of M Dwarfs (2019, background): “Additional studies with Kepler (e.g. Van Doorsselaere et al. 2017), K2 (Stelzer et al. 2016), MEarth (Mondrik et al. 2019) and others can provided an expanded view into the M dwarf regime, yet still for lim- 10 ited sample sizes.”
The minimum-mass extrasolar nebula: in situ formation of close-in super-Earths (2012, background): “The MEarth Project currently sets exposure times to detect planets with R = 2R⊕ at 3σ confidence (Berta et al. 2012).”
Observations of Transiting Exoplanets with the James Webb Space Telescope (JWST) (2014, background): “MEarth (Nutzman & Charbonneau 2008; Berta et al. 2012a) began monitoring the northern sky with eight 40-cm telescopes in 2008 and recently expanded to the southern sky with an additional eight telescopes.”
The Occurrence and Architecture of Exoplanetary Systems (2014, background): “…surveys is underway, aiming to extend the hunt beyond their traditional quarry of hot Jupiters into the realm of Neptune-sized planets (Bakos et al. 2013, Wheatley et al. 2013), or even smaller planets around M dwarfs (Nutzman & Charbonneau 2008, Giacobbe et al. 2012, Gillon et al. 2013).”
AN ALL-SKY CATALOG OF BRIGHT M DWARFS (2011, background): “Because of their significantly smaller radii, M dwarfs display deeper transits which do not require high precision photometry for detection, as they do for G stars (Nutzman & Charbonneau 2008).”
CHARACTERIZING THE COOL KOIs. IV. KEPLER-32 AS A PROTOTYPE FOR THE FORMATION OF COMPACT PLANETARY SYSTEMS THROUGHOUT THE GALAXY (2012, background): “…transits per observing period (Gould et al. 2003); transit depths are larger for a given planet radius allowing detections of ever smaller planets (Nutzman & Charbonneau 2008); and the reduced temperatures and luminosities of their host stars lead to equilibrium temperatures comparable to the…”
HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES (2013, background): “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.”
ON THE ANGULAR MOMENTUM EVOLUTION OF FULLY CONVECTIVE STARS: ROTATION PERIODS FOR FIELD M-DWARFS FROM THE MEarth TRANSIT SURVEY (2010, methodology): “Targets for the MEarth survey were selected by Nutzman & Charbonneau (2008) from a subsample of stars from the LSPM-North catalog (Lépine & Shara 2005) with trigonometric parallaxes or spectroscopic or photometric distance moduli indicating they are within 33 pc (Lépine 2005).”
The Habitability of Planets Orbiting M-dwarf Stars (2016, methodology): “…their habitable zones are much closer to the stars than those of Sun-like stars, increasing the geometric probability of observing a transit (Gould et al., 2003; Nutzman & Charbonneau, 2008a), as well as the frequency of transits of habitable-zone planets during a given observational time period.”
TRANSIT DETECTION IN THE MEarth SURVEY OF NEARBY M DWARFS: BRIDGING THE CLEAN-FIRST, SEARCH-LATER DIVIDE (2012, methodology): “These advantages aid the initial discovery (Nutzman & Charbonneau 2008; Blake et al. 2008) and the later detailed characterization (e.g. Deming et al. 2009) of planets that could be small enough and cool enough to potentially host life.”
THE OCCURRENCE RATE OF SMALL PLANETS AROUND SMALL STARS (2013, background): “…the difficulty of detecting a habitable planet and has motivated numerous planet surveys to target M dwarfs (Delfosse et al. 1999; Endl et al. 2003; Nutzman & Charbonneau 2008; Zechmeister et al. 2009; Apps et al. 2010; Barnes et al. 2012; Berta et al. 2012; Bowler et al. 2012; Giacobbe et al.…”
ZODIACAL EXOPLANETS IN TIME (ZEIT). III. A SHORT-PERIOD PLANET ORBITING A PRE-MAIN-SEQUENCE STAR IN THE UPPER SCORPIUS OB ASSOCIATION (2016, methodology): “Transit photometry from MEarth We observed two additional transits of K2-33b using the MEarth-North and MEarth-South arrays (Nutzman & Charbonneau 2008; Berta et al. 2012; Irwin et al. 2015) on February 16, 2016 and on March 14, 2016 (UT).”
A FRAMEWORK FOR CHARACTERIZING THE ATMOSPHERES OF LOW-MASS LOW-DENSITY TRANSITING PLANETS (2013, background): “With the rise of specialized ground-based transit survey for M dwarfs (Nutzman & Charbonneau 2008; Berta et al. 2012b; Giacobbe et al. 2012; Sozzetti et al. 2013) and the Transiting Exoplanet Survey Satellite (Ricker et al. 2010), the prospects are extremely good.”
The HARPS search for southern extra-solar planets - XXXI. The M-dwarf sample (2011, background): “Most recently, the Mearth project, a search for transiting planets dedicated to late M dwarfs (Nutzman & Charbonneau 2008), has unveiled a ∼ 6 M⊕ planet transiting the nearby M4.”
Transits and Occultations (2010, background): “…mentioned in Section 5.1, is specifically targeting small and low-luminosity stars because of the less stringent requirements on photometric precision and because the habitable zones occur at smaller orbital distances, making transits more likely and more frequent (Nutzman & Charbonneau 2008).”