Steps towards eta-Earth, from Kepler data

2014 ◽  
Vol 14 (3) ◽  
pp. 359-363 ◽  
Author(s):  
Wesley A. Traub
Keyword(s):  
Region Of Interest ◽  
Analytical Form ◽  
Terrestrial Planets ◽  
Model Parameters ◽  
Habitable Zone ◽  
Underlying Distribution ◽  
Habitable Zones ◽  
Kepler Mission ◽  
Instrument Noise ◽  
Minimal Bias

AbstractThe goal of this paper is to take steps towards estimating the frequency of terrestrial planets in the habitable zones of their host stars, using planet counts from the Kepler mission. The method is to assume that an analytical form for the underlying distribution function, numerically simulate the observing procedure, compare the simulated and real observations, and iterate the model parameters to achieve convergence in the sense of least-squares. The underlying distribution can then be extrapolated to a region of interest, here the terrestrial habitable-zone range. In this regime (small radii, long periods), the instrument noise makes such detections essentially impossible below a fairly sharply defined threshold signal level. This threshold can be estimated from the existing data. By taking this cutoff into account, the distribution of planets, as a function of radius and period, can be estimated with minimal bias. Extending this distribution to terrestrial planets in habitable-zone orbits can yield an estimate of eta-sub-Earth.

Formation, Frequency and Spacing of Habitable Planets

1997 ◽  
Vol 161 ◽  
pp. 289-297
Author(s):  
Jack J. Lissauer
Keyword(s):  
Planet Formation ◽  
Orbital Stability ◽  
Young Stars ◽  
Giant Planets ◽  
Terrestrial Planets ◽  
Habitable Zone ◽  
Habitable Planets ◽  
Habitable Zones ◽  
Planetary Orbits ◽  
Rocky Planets

AbstractModels of planet formation and of the orbital stability of planetary systems are described and used to discuss estimates of the abundance of habitable planets which may orbit stars within our galaxy. Modern theories of star and planet formation, which are based upon observations of the Solar System and of young stars and their environments, predict that most single stars should have rocky planets in orbit about them. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets orbiting within or near the habitable zone could either prevent terrestrial planets from forming, destroy such planets or remove them from habitable zones. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

scholarly journals A Step Toward Eta-sub-Earth

2012 ◽  
Vol 8 (S293) ◽  
pp. 84-87
Author(s):  
Wesley A. Traub
Keyword(s):  
Type Star ◽  
Terrestrial Planets ◽  
Habitable Zone ◽  
Reaction Wheel ◽  
Expected Number ◽  
Initial Examination ◽  
True Value ◽  
Kepler Mission ◽  
Solar Type ◽  
Solar Type Star

AbstractThe Kepler mission observed exoplanet transits for 4 full years (greater than its expected lifetime of 3.5 years) until it became inoperable for its original purpose, as a result of a reaction wheel failure. Kepler was spectacularly successful in its goal of observing exoplanet transits of host star disks for the purpose of measuring the statistics of such transits in its target star sample. The Kepler data, when fully analyzed, will determine the statistics of planets in the underlying population, and in particular the expected number of terrestrial planets in habitable zone orbits per solar-type star, the quantity known as eta-sub-Earth. This report is an initial examination of Kepler's third catalog (Feb. 2012) of planets and candidate planets. I find that the apparent projected value of eta-sub-Earth is several times smaller than I had found from the second catalog, but that the data are now approaching the point where intrinsic biases can be uncovered. When all bias factors are eventually found, it is likely that the true value of eta-sub-Earth will be substantially greater than its current apparent value.

scholarly journals Characteristics of the Kepler target stars

2009 ◽  
Vol 5 (H15) ◽  
pp. 712-713
Author(s):  
Natalie M. Batalha ◽  
William J. Borucki ◽  
David G. Koch ◽  
Timothy M. Brown ◽  
Douglas A. Caldwell ◽  
...  
Keyword(s):  
Field Of View ◽  
Habitable Zone ◽  
Late Type ◽  
Mission Duration ◽  
Habitable Zones ◽  
Kepler Mission ◽  
Orbital Periods

AbstractThe Kepler Mission successfully launched March 6, 2009, beginning its 3.5-year mission to determine the frequency of Earth-size planets in the habitable zones of late-type stars. The brightnesses of over 100,000 stars are currently being monitored for transit events with an expected differential photometric precision of 20 ppm at V=12 for a 6.5-hour transit. The same targets will be observed continuously over the mission duration in order to broaden the detection space to orbital periods comparable to that of Earth. This paper provides an overview of the selection and prioritization criteria used to choose the stars that Kepler is observing from the > 4.5 million objects in the 100 square degree field of view. The characteristics of the Kepler targets are described as well as the implications for detectability of planets in the habitable zone smaller than 2R⊕.

scholarly journals Earth-size planet formation in the habitable zone of circumbinary stars

2020 ◽  
Vol 494 (1) ◽  
pp. 1045-1057 ◽  
Author(s):  
G O Barbosa ◽  
O C Winter ◽  
A Amarante ◽  
A Izidoro ◽  
R C Domingos ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Planet Formation ◽  
Terrestrial Planet ◽  
Close Binary ◽  
Habitable Zone ◽  
Density Profiles ◽  
Habitable Planets ◽  
Habitable Zones ◽  
Test Particles ◽  
The Stability

ABSTRACT This work investigates the possibility of close binary (CB) star systems having Earth-size planets within their habitable zones (HZs). First, we selected all known CB systems with confirmed planets (totaling 22 systems) to calculate the boundaries of their respective HZs. However, only eight systems had all the data necessary for the computation of HZ. Then, we numerically explored the stability within HZs for each one of the eight systems using test particles. From the results, we selected five systems that have stable regions inside HZs, namely Kepler-34,35,38,413, and 453. For these five cases of systems with stable regions in HZ, we perform a series of numerical simulations for planet formation considering discs composed of planetary embryos and planetesimals, with two distinct density profiles, in addition to the stars and host planets of each system. We found that in the case of the Kepler-34 and 453 systems, no Earth-size planet is formed within HZs. Although planets with Earth-like masses were formed in Kepler-453, they were outside HZ. In contrast, for the Kepler-35 and 38 systems, the results showed that potentially habitable planets are formed in all simulations. In the case of the Kepler-413system, in just one simulation, a terrestrial planet was formed within HZ.

scholarly journals On the abundance of extraterrestrial life after the Kepler mission

2015 ◽  
Vol 14 (3) ◽  
pp. 511-516 ◽  
Author(s):  
Amri Wandel
Keyword(s):  
Significant Fraction ◽  
Habitable Zone ◽  
Radio Telescopes ◽  
Extraterrestrial Life ◽  
Space Density ◽  
Astronomical Data ◽  
Unknown Probability ◽  
Kepler Mission ◽  
Average Longevity ◽  
Electromagnetic Signals

AbstractThe data recently accumulated by the Kepler mission have demonstrated that small planets are quite common and that a significant fraction of all stars may have an Earth-like planet within their habitable zone. These results are combined with a Drake-equation formalism to derive the space density of biotic planets as a function of the relatively modest uncertainty in the astronomical data and of the (yet unknown) probability for the evolution of biotic life, Fb. I suggest that Fb may be estimated by future spectral observations of exoplanet biomarkers. If Fb is in the range 0.001–1, then a biotic planet may be expected within 10–100 light years from Earth. Extending the biotic results to advanced life I derive expressions for the distance to putative civilizations in terms of two additional Drake parameters – the probability for evolution of a civilization, Fc, and its average longevity. For instance, assuming optimistic probability values (Fb~Fc~1) and a broadcasting longevity of a few thousand years, the likely distance to the nearest civilizations detectable by searching for intelligent electromagnetic signals is of the order of a few thousand light years. The probability of detecting intelligent signals with present and future radio telescopes is calculated as a function of the Drake parameters. Finally, I describe how the detection of intelligent signals would constrain the Drake parameters.

scholarly journals The Potential for Archaeology Within and Beyond the Habitable Zones (HZ) of the Milky Way

2004 ◽  
Vol 213 ◽  
pp. 505-510
Author(s):  
John B. Campbell
Keyword(s):  
Remote Sensing ◽  
Solar System ◽  
Milky Way ◽  
Extrasolar Planets ◽  
Habitable Zone ◽  
The Moon ◽  
Habitable Zones ◽  
Remote Sensing Techniques ◽  
Main Region

As archaeology is established on Earth and we are actively exploring the Solar System and beyond, there is the potential to develop a number of forms of exo-archaeology. The archaeology of the things intelligent species do in theory could be practised anywhere, provided one can detect the evidence. Sites are being created by us elsewhere within our star's habitable zone (HZ), namely on the Moon and Mars, and at least molecular traces of human-created probes are being left beyond the HZ (Venus, Jupiter etc.). The successful detection of extrasolar planets and the possible identification of HZs round other stars raise the possibility for the development of extrasolar archaeology, at least initially by remote sensing techniques. Within the Milky Way the main region to investigate is the galactic habitable zone (GHZ), though there could be archaeological traces of technological behaviours beyond it.

scholarly journals Resilient habitability of nearby exoplanet systems

2019 ◽  
Vol 492 (1) ◽  
pp. 352-368 ◽  
Author(s):  
Giorgi Kokaia ◽  
Melvyn B Davies ◽  
Alexander J Mustill
Keyword(s):  
Giant Planet ◽  
Planetary Systems ◽  
Observational Constraints ◽  
Habitable Zone ◽  
Habitable Zones ◽  
Test Particles ◽  
Planetary Orbits ◽  
Two Systems ◽  
Earth Like Planets ◽  
Exoplanet Systems

ABSTRACT We investigate the possibility of finding Earth-like planets in the habitable zone of 34 nearby FGK-dwarfs, each known to host one giant planet exterior to their habitable zone detected by RV. First we simulate the dynamics of the planetary systems in their present day configurations and determine the fraction of stable planetary orbits within their habitable zones. Then, we postulate that the eccentricity of the giant planet is a result of an instability in their past during which one or more other planets were ejected from the system. We simulate these scenarios and investigate whether planets orbiting in the habitable zone survive the instability. Explicitly we determine the fraction of test particles, originally found in the habitable zone, which remain in the habitable zone today. We label this fraction the resilient habitability of a system. We find that for most systems the probability of planets existing [or surviving] on stable orbits in the habitable zone becomes significantly smaller when we include a phase of instability in their history. We present a list of candidate systems with high resilient habitability for future observations. These are: HD 95872, HD 154345, HD 102843, HD 25015, GJ 328, HD 6718, and HD 150706. The known planets in the last two systems have large observational uncertainties on their eccentricities, which propagate into large uncertainties on their resilient habitability. Further observational constraints of these two eccentricities will allow us to better constrain the survivability of Earth-like planets in these systems.

scholarly journals Searching for Planetary Companions to Ultracool Dwarfs: Planet Hunting in the Near Infrared

2008 ◽  
Vol 4 (S253) ◽  
pp. 346-349
Author(s):  
Cullen H. Blake ◽  
David Charbonneau ◽  
David W. Latham
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Extrasolar Planets ◽  
Terrestrial Planets ◽  
Habitable Zone ◽  
Velocity Measurements ◽  
Ultracool Dwarfs

AbstractOwing to their small masses and radii, Ultracool Dwarfs (UCDs; late-M, L, and T dwarfs) may be excellent targets for planet searches and may afford astronomers the opportunity to detect terrestrial planets in the habitable zone. The precise measurements necessary to detect extrasolar planets orbiting UCDs represent a major challenge. We describe two efforts to obtain precise measurements of UCDs in the Near Infrared (NIR). The first involves the robotic NIR observatory PAIRITEL and efforts to obtain photometric precision sufficient for the detection of terrestrial planets transiting UCDs. The second effort involves precise radial velocity measurements of UCDs in the NIR and a survey undertaken with the NIRSPEC spectrograph on Keck.

scholarly journals The Mt John University Observatory search for Earth-mass planets in the habitable zone of α Centauri

2014 ◽  
Vol 14 (2) ◽  
pp. 305-312 ◽  
Author(s):  
Michael Endl ◽  
Christoph Bergmann ◽  
John Hearnshaw ◽  
Stuart I. Barnes ◽  
Robert A. Wittenmyer ◽  
...  
Keyword(s):  
High Efficiency ◽  
Detection Sensitivity ◽  
Habitable Zone ◽  
Echelle Spectrograph ◽  
Planet Detection ◽  
The Past ◽  
Temporal Sampling ◽  
Habitable Zones ◽  
Low Mass ◽  
Advanced Version

AbstractThe ‘holy grail’ in planet hunting is the detection of an Earth-analogue: a planet with similar mass as the Earth and an orbit inside the habitable zone. If we can find such an Earth-analogue around one of the stars in the immediate solar neighbourhood, we could potentially even study it in such great detail to address the question of its potential habitability. Several groups have focused their planet detection efforts on the nearest stars. Our team is currently performing an intensive observing campaign on the α Centauri system using the High Efficiency and Resolution Canterbury University Large Échelle Spectrograph (Hercules) at the 1 m McLellan telescope at Mt John University Observatory in New Zealand. The goal of our project is to obtain such a large number of radial velocity (RV) measurements with sufficiently high temporal sampling to become sensitive to signals of Earth-mass planets in the habitable zones of the two stars in this binary system. Over the past few years, we have collected more than 45 000 spectra for both stars combined. These data are currently processed by an advanced version of our RV reduction pipeline, which eliminates the effect of spectral cross-contamination. Here we present simulations of the expected detection sensitivity to low-mass planets in the habitable zone by the Hercules programme for various noise levels. We also discuss our expected sensitivity to the purported Earth-mass planet in a 3.24-day orbit announced by Dumusque et al. (2012).

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