scholarly journals Sensitivity to habitable planets in the Roman microlensing survey

2021 ◽  
Author(s):  
Sedighe Sajadian
Keyword(s):  
Habitable Zone ◽  
Mass Ratio ◽  
Galactic Bulge ◽  
Habitable Planets ◽  
Class A ◽  
Einstein Radius

Abstract We study the Roman sensitivity to exoplanets in the Habitable Zone (HZ). The Roman efficiency for detecting habitable planets is maximized for three classes of planetary microlensing events with close caustic topologies. (a) The events with the lens distances of Dl ≳ 7 kpc, the host lens masses of Mh ≳ 0.6 M⊙. By assuming Jupiter-mass planets in the HZs, these events have q ≲ 0.001 and d ≳ 0.17 (q is their mass ratio and d is the projected planet-host distance on the sky plane normalized to the Einstein radius). The events with primary lenses, Mh ≲ 0.1 M⊙, while their lens systems are either (b) close to the observer with Dl ≲ 1 kpc or (c) close to the Galactic bulge, Dl ≳ 7 kpc. For Jupiter-mass planets in the HZs of the primary lenses, the events in these two classes have q ≳ 0.01, d ≲ 0.04. The events in the class (a) make larger caustics. By simulating planetary microlensing events detectable by Roman, we conclude that the Roman efficiencies for detecting Earth- and Jupiter-mass planets in the Optimistic HZs (OHZs, which is the region between [0.5,  2] AU around a Sun-like star) are $0.01{{\ \rm per\ cent}}$ and $5{{\ \rm per\ cent}}$, respectively. If we assume that one exoplanet orbits each microlens in microlensing events detectable by Roman ( i.e. ∼27000 ), this telescope has the potential to detects 35 exoplanets with the projected planet-host distances in the OHZs with only one having a mass ≲ 10M⊕. According to the simulation, 27 of these exoplanets are actually in the OHZs.

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.

Longevity of moons around habitable planets

2014 ◽  
Vol 13 (4) ◽  
pp. 324-336 ◽  
Author(s):  
Takashi Sasaki ◽  
Jason W. Barnes
Keyword(s):  
Orbital Period ◽  
Extrasolar Planets ◽  
The Sun ◽  
Habitable Zone ◽  
Evolution Theory ◽  
Earth System ◽  
The Moon ◽  
Tidal Dissipation ◽  
Habitable Planets ◽  
Rocky Planets

AbstractWe consider tidal decay lifetimes for moons orbiting habitable extrasolar planets using the constant Q approach for tidal evolution theory. Large moons stabilize planetary obliquity in some cases, and it has been suggested that large moons are necessary for the evolution of complex life. We find that the Moon in the Sun–Earth system must have had an initial orbital period of not slower than 20 h rev−1 for the moon's lifetime to exceed a 5 Gyr lifetime. We assume that 5 Gyr is long enough for life on planets to evolve complex life. We show that moons of habitable planets cannot survive for more than 5 Gyr if the stellar mass is less than 0.55 and 0.42 M⊙ for Qp=10 and 100, respectively, where Qp is the planetary tidal dissipation quality factor. Kepler-62e and f are of particular interest because they are two actually known rocky planets in the habitable zone. Kepler-62e would need to be made of iron and have Qp=100 for its hypothetical moon to live for longer than 5 Gyr. A hypothetical moon of Kepler-62f, by contrast, may have a lifetime greater than 5 Gyr under several scenarios, and particularly for Qp=100.

scholarly journals A More Comprehensive Habitable Zone for Finding Life on Other Planets

Geosciences ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 280 ◽  
Author(s):  
Ramses Ramirez
Keyword(s):  
Greenhouse Gases ◽  
Main Sequence ◽  
Habitable Zone ◽  
Circular Region ◽  
Main Sequence Stars ◽  
Habitable Planets ◽  
Host Life ◽  
Navigational Tool ◽  
Bodies Of Water

The habitable zone (HZ) is the circular region around a star(s) where standing bodies of water could exist on the surface of a rocky planet. Space missions employ the HZ to select promising targets for follow-up habitability assessment. The classical HZ definition assumes that the most important greenhouse gases for habitable planets orbiting main-sequence stars are CO2 and H2O. Although the classical HZ is an effective navigational tool, recent HZ formulations demonstrate that it cannot thoroughly capture the diversity of habitable exoplanets. Here, I review the planetary and stellar processes considered in both classical and newer HZ formulations. Supplementing the classical HZ with additional considerations from these newer formulations improves our capability to filter out worlds that are unlikely to host life. Such improved HZ tools will be necessary for current and upcoming missions aiming to detect and characterize potentially habitable exoplanets.

scholarly journals Estimating Finite Source Effects in Microlensing Events due to Free-Floating Planets with the Euclid Survey

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Lindita Hamolli ◽  
Mimoza Hafizi ◽  
Francesco De Paolis ◽  
Achille A. Nucita
Keyword(s):  
Spatial Distribution ◽  
Power Law ◽  
Mass Function ◽  
Physical Parameters ◽  
Galactic Bulge ◽  
Source Effect ◽  
Source Effects ◽  
Function Index ◽  
Finite Source ◽  
Einstein Radius

In recent years free-floating planets (FFPs) have drawn a great interest among astrophysicists. Gravitational microlensing is a unique and exclusive method for their investigation which may allow obtaining precious information about their mass and spatial distribution. The planned Euclid space-based observatory will be able to detect a substantial number of microlensing events caused by FFPs towards the Galactic bulge. Making use of a synthetic population algorithm, we investigate the possibility of detecting finite source effects in simulated microlensing events due to FFPs. We find a significant efficiency for finite source effect detection that turns out to be between 20% and 40% for a FFP power law mass function index in the range [0.9, 1.6]. For many of such events it will also be possible to measure the angular Einstein radius and therefore constrain the lens physical parameters. These kinds of observations will also offer a unique possibility to investigate the photosphere and atmosphere of Galactic bulge stars.

scholarly journals Polarimetry as a tool to find and characterise habitable planets orbiting white dwarfs

2014 ◽  
Vol 10 (S305) ◽  
pp. 325-332 ◽  
Author(s):  
Luca Fossati ◽  
Stefano Bagnulo ◽  
Carole A. Haswell ◽  
Manish R. Patel ◽  
Richard Busuttil ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Uv Radiation ◽  
Uv Irradiation ◽  
White Dwarf ◽  
White Dwarfs ◽  
Terrestrial Planet ◽  
Habitable Zone ◽  
Habitable Planets ◽  
Earth Like Planets ◽  
M Dwarf

AbstractThere are several ways planets can survive the giant phase of the host star, hence one can consider the case of Earth-like planets orbiting white dwarfs. As a white dwarf cools from 6000 K to 4000 K, a planet orbiting at 0.01 AU from the star would remain in the continuous habitable zone (CHZ) for about 8 Gyr. Polarisation due to a terrestrial planet in the CHZ of a cool white dwarf (CWD) is 102 (104) times larger than it would be in the habitable zone of a typical M-dwarf (Sun-like star). Polarimetry is thus a powerful tool to detect close-in planets around white dwarfs. Multi-band polarimetry would also allow one to reveal the presence of a planet atmosphere, even providing a first characterisation. With current facilities a super-Earth-sized atmosphereless planet is detectable with polarimetry around the brightest known CWD. Planned future facilities render smaller planets detectable, in particular by increasing the instrumental sensitivity in the blue. Preliminary habitability study show also that photosynthetic processes can be sustained on Earth-like planets orbiting CWDs and that the DNA-weighted UV radiation dose for an Earth-like planet in the CHZ is less than the maxima encountered on Earth, hence white dwarfs are compatible with the persistence of complex life from the perspective of UV irradiation.

scholarly journals Formation of Habitable Planets in Inclined Planetary Systems

2012 ◽  
Vol 8 (S293) ◽  
pp. 238-240
Author(s):  
Jianghui Ji ◽  
Sheng Jin
Keyword(s):  
Late Stage ◽  
Planetary Systems ◽  
Numerical Results ◽  
The Other ◽  
Terrestrial Planets ◽  
Habitable Zone ◽  
Planetary Formation ◽  
Habitable Planets ◽  
Final Assembly ◽  
Inner Region

AbstractWe extensively investigate the terrestrial planetary formation for the inclined planetary systems (considering the OGLE-2006-BLG-109L system as example) in the late stage. In the simulations, we show that the occurrence of terrestrial planets appears to be common in the final assembly stage. Moreover, we find that a lot of runs finally occupy at least one planet in the habitable zone (HZ). On the other hand, the numerical results also indicate that the inner region of the planetesimal disk, ranging from ~ 0.1 to 0.3 AU, plays an important role in building up terrestrial planets. The outcomes suggest that it may exist moderate possibility for the inclined systems to harbor terrestrial planets in the HZ.

scholarly journals Physical properties of terrestrial planets and water delivery in the habitable zone using N-body simulations with fragmentation

2019 ◽  
Vol 632 ◽  
pp. A14 ◽  
Author(s):  
A. Dugaro ◽  
G. C. de Elía ◽  
L. A. Darriba
Keyword(s):  
Terrestrial Planets ◽  
Habitable Zone ◽  
Water Delivery ◽  
Class A ◽  
Class B ◽  
Solar Type ◽  
Formation And Evolution ◽  
Final Fraction ◽  
The Masses ◽  
Water Contents

Aims. The goal of this research is to study how the fragmentation of planetary embryos can affect the physical and dynamical properties of terrestrial planets around solar-type stars. Our study focuses on the formation and evolution of planets and water delivery in the habitable zone (HZ). We distinguish class A and class B HZ planets, which have an accretion seed initially located inside and beyond the snow line, respectively. Methods. We developed an N-body integrator that incorporates fragmentation and hit-and-run collisions, which is called D3 N-body code. From this, we performed 46 numerical simulations of planetary accretion in systems that host two gaseous giants similar to Jupiter and Saturn. We compared two sets of 23 N-body simulations, one of which includes a realistic collisional treatment and the other one models all impacts as perfect mergers. Results. The final masses of the HZ planets formed in runs with fragmentation are about 15–20% lower than those obtained without fragmentation. As for the class A HZ planets, those formed in simulations without fragmentation experience very significant increases in mass with respect to their initial values, while the growth of those produced in runs with fragmentation is less relevant. We remark that the fragments play a secondary role in the masses of the class A HZ planets, providing less than 30% of their final values. In runs without fragmentation, the final fraction of water of the class A HZ planets keeps the initial value since they do not accrete water-rich embryos. In runs with fragmentation, the final fraction of water of such planets strongly depends on the model used to distribute the water after each collision. The class B HZ planets do not show significant differences concerning their final water contents in runs with and without fragmentation. From this, we find that the collisional fragmentation is not a barrier to the survival of water worlds in the HZ.

Modelling the atmosphere of potential habitable planets

2018 ◽  
Vol 14 (S345) ◽  
pp. 172-175
Author(s):  
Nicolas Iro
Keyword(s):  
Radiative Transfer ◽  
One Dimension ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Habitable Zone ◽  
Habitable Planets

AbstractThe list of planets discovered in the habitable zone of its star is continuously growing. We present a simple one-dimension radiative transfer model in order to better infer on the habitability of such systems. Particular focus is on the TRAPPIST-1 planets (Gillon et al.2017), particularly on planets b, c, d, e and f.

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.

Pollination of exoplanets by nebulae

2007 ◽  
Vol 6 (3) ◽  
pp. 223-228 ◽  
Author(s):  
W.M. Napier
Keyword(s):  
Solar System ◽  
Molecular Cloud ◽  
Oort Cloud ◽  
Habitable Zone ◽  
Habitable Planets ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Earth ◽  
The Galaxy ◽  
Micro Organisms

AbstractThe Solar System passes within 5 pc of star-forming nebulae every ∼50–100 million years, a distance which can be bridged by protected micro-organisms ejected from the Earth by impacts. Such encounters disturb the Oort cloud, and induce episodes of bombardment of the Earth and the ejection of microbiota from its surface. Star-forming regions within the nebulae encountered may thus be seeded by significant numbers of microorganisms. Propagation of life throughout the Galactic habitable zone ‘goes critical’ provided that, in a typical molecular cloud, there are at least 1.1 habitable planets with impact environments similar to that of the Earth. Dissemination of microbiota proceeds most rapidly through the molecular ring of the Galaxy.

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