GJ 273: on the formation, dynamical evolution, and habitability of a planetary system hosted by an M dwarf at 3.75 parsec

Context. Planets orbiting low-mass stars such as M dwarfs are now considered a cornerstone in the search for planets with the potential to harbour life. GJ 273 is a planetary system orbiting an M dwarf only 3.75 pc away, which is composed of two confirmed planets, GJ 273b and GJ 273c, and two promising candidates, GJ 273d and GJ 273e. Planet GJ 273b resides in the habitable zone. Currently, due to a lack of observed planetary transits, only the minimum masses of the planets are known: Mb sin ib = 2.89 M⊕, Mc sin ic = 1.18 M⊕, Md sin id = 10.80 M⊕, and Me sin ie = 9.30 M⊕. Despite its interesting character, the GJ 273 planetary system has been poorly studied thus far. Aims. We aim to precisely determine the physical parameters of the individual planets, in particular, to break the mass–inclination degeneracy to accurately determine the mass of the planets. Moreover, we present a thorough characterisation of planet GJ 273b in terms of its potential habitability. Methods. First, we explored the planetary formation and hydration phases of GJ 273 during the first 100 Myr. Secondly, we analysed the stability of the system by considering both the two- and four-planet configurations. We then performed a comparative analysis between GJ 273 and the Solar System and we searched for regions in GJ 273 which may harbour minor bodies in stable orbits, that is, the main asteroid belt and Kuiper belt analogues. Results. From our set of dynamical studies, we find that the four-planet configuration of the system allows us to break the mass–inclination degeneracy. From our modelling results, the masses of the planets are unveiled as: 2.89 ≤ Mb ≤ 3.03 M⊕, 1.18 ≤ Mc ≤ 1.24 M⊕, 10.80 ≤ Md ≤ 11.35 M⊕, and 9.30 ≤ Me ≤ 9.70 M⊕. These results point to a system that is likely to be composed of an Earth-mass planet, a super-Earth and two mini-Neptunes. Based on planetary formation models, we determine that GJ 273b is likely an efficient water captor while GJ 273c is probably a dry planet. We find that the system may have several stable regions where minor bodies might reside. Collectively, these results are used to offer a comprehensive discussion about the habitability of GJ 273b.

Download Full-text

Mass determination of the 1:3:5 near-resonant planets transiting GJ 9827 (K2-135)

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832872 ◽

2018 ◽

Vol 618 ◽

pp. A116 ◽

Cited By ~ 13

Author(s):

J. Prieto-Arranz ◽

E. Palle ◽

D. Gandolfi ◽

O. Barragán ◽

E. W. Guenther ◽

...

Keyword(s):

Planetary System ◽

Initial Conditions ◽

Dynamical Evolution ◽

Space Mission ◽

Mass Determination ◽

Velocity Measurements ◽

Orbital Periods ◽

The Masses ◽

Better Than

Context. Multiplanet systems are excellent laboratories to test planet formation models as all planets are formed under the same initial conditions. In this context, systems transiting bright stars can play a key role, since planetary masses, radii, and bulk densities can be measured. Aims. GJ 9827 (K2-135) has recently been found to host a tightly packed system consisting of three transiting small planets whose orbital periods of 1.2, 3.6, and 6.2 days are near the 1:3:5 ratio. GJ 9827 hosts the nearest planetary system (~30 pc) detected by NASA’s Kepler or K2 space mission. Its brightness (V = 10.35 mag) makes the star an ideal target for detailed studies of the properties of its planets. Methods. Combining the K2 photometry with high-precision radial-velocity measurements gathered with the FIES, HARPS, and HARPS-N spectrographs we revised the system parameters and derive the masses of the three planets. Results. We find that GJ 9827 b has a mass of Mb = 3.69−0.46+0.48 M⊕ and a radius of Rb = 1.58−0.13+0.14 R⊕, yielding a mean density of ρb = 5.11−1.27+1.74 g cm−3. GJ 9827 c has a mass of Mc = 1.45−0.57+0.58 M⊕, radius of Rc = 1.24−0.11+0.11 R⊕, and a mean density of ρc = 4.13−1.77+2.31 g cm−3. For GJ 9827 d, we derive Md = 1.45−0.57+0.58 M⊕, Rd = 1.24−0.11+0.11 R⊕, and ρd = 1.51−0.53+0.71 g cm−3. Conclusions. GJ 9827 is one of the few known transiting planetary systems for which the masses of all planets have been determined with a precision better than 30%. This system is particularly interesting because all three planets are close to the limit between super-Earths and sub-Neptunes. The planetary bulk compositions are compatible with a scenario where all three planets formed with similar core and atmosphere compositions, and we speculate that while GJ 9827 b and GJ 9827 c lost their atmospheric envelopes, GJ 9827 d maintained its primordial atmosphere, owing to the much lower stellarirradiation. This makes GJ 9827 one of the very few systems where the dynamical evolution and the atmosphericescape can be studied in detail for all planets, helping us to understand how compact systems form and evolve.

Download Full-text

Comets (Existing Populations)

Symposium - International Astronomical Union ◽

10.1017/s0074180900046477 ◽

1994 ◽

Vol 160 ◽

pp. 77-94

Author(s):

Ľ. Kresák

Keyword(s):

Kuiper Belt ◽

Dynamical Evolution ◽

Oort Cloud ◽

Survival Times ◽

Evolutionary Time ◽

Origin And Evolution ◽

History Of ◽

The Individual ◽

Evolutionary Paths

The definition, population, extent, origin and evolution of the individual subsystems of comets and transitions between them are discussed, together with presentation of the relevant statistical data and their changes with time. The largest outer subsystems are unobservable, but their existence is documented by the necessity of progressive replenishment of the observable populations, with limited survival times. There is persuasive evidence for two different evolutionary paths, one from the Oort cloud and another from the Kuiper belt. While the extent and accuracy of the data available is increasing rapidly, the Jupiter family of comets is the only one for which the evolutionary time scales do not exceed by many orders of magnitude the history of astronomical observations. The individual comet populations differ from one another not only by the distribution of orbits, but also by the size distribution and aging rate of their members. Their dynamical evolution is coupled with disintegration processes, which make it questionable whether the present state can be interpreted as a long-term average.

Download Full-text

Masses of asteroids and total mass of the main asteroid belt

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315008388 ◽

2015 ◽

Vol 10 (S318) ◽

pp. 212-217

Author(s):

E. V. Pitjeva ◽

N. P. Pitjev

Keyword(s):

Total Mass ◽

Radar Data ◽

Asteroid Belt ◽

Two Dimensional ◽

Binary Asteroids ◽

One Dimensional ◽

Main Asteroid Belt ◽

The Individual ◽

The Masses ◽

Academy Of Sciences

AbstractAn estimation of the mass of the main asteroid belt was made on the basis of the new version of EPM2014 ephemerides of the Institute of Applied Astronomy of Russian Academy of Sciences using about 800000 positional observations of planets and spacecraft. We obtained the individual estimations of masses of large asteroids from radar data, as well as estimates of the masses of asteroids by using known diameters and estimated average densities for the three taxonomic types (C, S, M), and used the known mass values of binary asteroids and asteroids to which spacecraft approached. A two-dimensional homogeneous annulus with dimensions corresponding observed width of the main asteroid belt (2.06 au and 3.27 au) was used instead of a previous massive one-dimensional ring for modeling total perturbations from small asteroids. The obtained value of the total mass of the main asteroid belt is (12.25 ± 0.19)10−10M⊙.

Download Full-text

K2-19, The first K2 muti-planetary system showing TTVs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316002386 ◽

2015 ◽

Vol 11 (A29A) ◽

pp. 51-56

Author(s):

S. C. C. Barros ◽

J. M. Almenara ◽

O. Demangeon ◽

M. Tsantaki ◽

A. Santerne ◽

...

Keyword(s):

System Architecture ◽

Planetary System ◽

Light Curves ◽

Dynamical Model ◽

Dynamic Simulations ◽

Short Period ◽

Resonant Systems ◽

The Individual ◽

The Masses ◽

Body Dynamic

AbstractIn traditional transit timing variations (TTVs) analysis of multi-planetary systems, the individual TTVs are first derived from transit fitting and later modelled using n-body dynamic simulations to constrain planetary masses. We show that fitting simultaneously the transit light curves with the system dynamics (photo-dynamical model) increases the precision of the TTV measurements and helps constrain the system architecture. We exemplify the advantages of applying this photo-dynamical model to a multi-planetary system found in K2 data very close to 3:2 mean motion resonance, K2-19. In this case the period of the larger TTV variations (libration period) is much longer (>1.5 years) than the duration of the K2 observations (80 days). However, our method allows to detect the short period TTVs produced by the orbital conjunctions between the planets that in turn permits to uniquely characterise the system. Therefore, our method can be used to constrain the masses of near-resonant systems even when the full libration curve is not observed.

Download Full-text

The Locations of Secular Resonances and the Evolution of Small Solar System Bodies

Symposium - International Astronomical Union ◽

10.1017/s0074180900091026 ◽

1992 ◽

Vol 152 ◽

pp. 123-132

Author(s):

Ch Froeschle ◽

P. Farinella ◽

C. Froeschle ◽

Z. Knežević ◽

A. Milani

Keyword(s):

Perturbation Theory ◽

Solar System ◽

Small Body ◽

Kuiper Belt ◽

Dynamical Evolution ◽

Asteroid Belt ◽

Secular Resonances ◽

Outer Planets ◽

Proper Elements ◽

Solar System Bodies

Generalizing the secular perturbation theory of Milani and Knežević (1990), we have determined in the a — e — I proper elements space the locations of the secular resonances between the precession rates of the longitudes of perihelion and node of a small body and the corresponding eigenfrequencies of the secular perturbations of the four outer planets. We discuss some implications of the results for the dynamical evolution of small solar system bodies. In particular, our findings include: (i) the fact that the g = g6 resonance in the inner asteroid belt lies closer than previously assumed to the Flora region, providing a plausible dynamical route to inject asteroid fragments into planet-crossing orbits; (ii) the possible presence of some low-inclination “stable islands” between the orbits of the outer planets; (iii) the fact that none of the secular resonances considered in this work exists for semimajor axes > 50 AU, so that these resonances do not provide a mechanism for transporting inwards possible Kuiper–belt comets.

Download Full-text

The CARMENES search for exoplanets around M dwarfs

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037867 ◽

2020 ◽

Vol 642 ◽

pp. A173 ◽

Cited By ~ 1

Author(s):

G. Nowak ◽

R. Luque ◽

H. Parviainen ◽

E. Pallé ◽

K. Molaverdikhani ◽

...

Keyword(s):

Planetary System ◽

Outer Planet ◽

Planetary Formation ◽

Atmospheric Models ◽

M Dwarfs ◽

Ideal Object ◽

Transiting Planets ◽

Short Period ◽

Iron Abundance ◽

M Dwarf

We present the discovery and characterisation of two transiting planets observed by the Transiting Exoplanet Survey Satellite (TESS) orbiting the nearby (d⋆ ≈ 22 pc), bright (J ≈ 9 mag) M3.5 dwarf LTT 3780 (TOI–732). We confirm both planets and their association with LTT 3780 via ground-based photometry and determine their masses using precise radial velocities measured with the CARMENES spectrograph. Precise stellar parameters determined from CARMENES high-resolution spectra confirm that LTT 3780 is a mid-M dwarf with an effective temperature of Teff = 3360 ± 51 K, a surface gravity of log g⋆ = 4.81 ± 0.04 (cgs), and an iron abundance of [Fe/H] = 0.09 ± 0.16 dex, with an inferred mass of M⋆ = 0.379 ± 0.016M⊙ and a radius of R⋆ = 0.382 ± 0.012R⊙. The ultra-short-period planet LTT 3780 b (Pb = 0.77 d) with a radius of 1.35−0.06+0.06 R⊕, a mass of 2.34−0.23+0.24 M⊕, and a bulk density of 5.24−0.81+0.94 g cm−3 joins the population of Earth-size planets with rocky, terrestrial composition. The outer planet, LTT 3780 c, with an orbital period of 12.25 d, radius of 2.42−0.10+0.10 R⊕, mass of 6.29−0.61+0.63 M⊕, and mean density of 2.45−0.37+0.44 g cm−3 belongs to the population of dense sub-Neptunes. With the two planets located on opposite sides of the radius gap, this planetary system is anexcellent target for testing planetary formation, evolution, and atmospheric models. In particular, LTT 3780 c is an ideal object for atmospheric studies with the James Webb Space Telescope (JWST).

Download Full-text

Exploring the conditions for forming cold gas giants through planetesimal accretion

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936351 ◽

2019 ◽

Vol 631 ◽

pp. A70 ◽

Cited By ~ 7

Author(s):

Anders Johansen ◽

Bertram Bitsch

Keyword(s):

Kuiper Belt ◽

Oort Cloud ◽

Asteroid Belt ◽

Nominal Model ◽

The Core ◽

And Migration ◽

The Masses ◽

Core Accretion ◽

Cold Gas ◽

Protoplanetary Discs

The formation of cold gas giants similar to Jupiter and Saturn in orbit and mass is a great challenge for planetesimal-driven core accretion models because the core growth rates far from the star are low. Here we model the growth and migration of single protoplanets that accrete planetesimals and gas. We integrated the core growth rate using fits in the literature to N-body simulations, which provide the efficiency of accreting the planetesimals that a protoplanet migrates through. We take into account three constraints from the solar system and from protoplanetary discs: (1) the masses of the terrestrial planets and the comet reservoirs in Neptune’s scattered disc and the Oort cloud are consistent with a primordial planetesimal population of a few Earth masses per AU, (2) evidence from the asteroid belt and the Kuiper belt indicates that the characteristic planetesimal diameter is 100 km, and (3) observations of protoplanetary discs indicate that the dust is stirred by weak turbulence; this gas turbulence also excites the inclinations of planetesimals. Our nominal model built on these constraints results in maximum protoplanet masses of 0.1 Earth masses. Ignoring constraint (1) above, we show that even a planetesimal population of 1000 Earth masses, corresponding to 50 Earth masses per AU, fails to produce cold gas giants (although it successfully forms hot and warm gas giants). We conclude that a massive planetesimal reservoir is in itself insufficient to produce cold gas giants. The formation of cold gas giants by planetesimal accretion additionally requires that planetesimals are small and that the turbulent stirring is very weak, thereby violating all three above constraints.

Download Full-text

Characterising young visual M-dwarf binaries with near-infrared integral field spectra

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038030 ◽

2020 ◽

Vol 642 ◽

pp. A57

Author(s):

Per Calissendorff ◽

Markus Janson ◽

Mickaël Bonnefoy

Keyword(s):

Near Infrared ◽

Evolutionary Models ◽

Low Mass Stars ◽

Multiple Systems ◽

Low Mass ◽

Moving Groups ◽

Band Spectra ◽

The Individual ◽

M Dwarf ◽

Integral Field

We present the results from an integral field spectroscopy study of seven close visual binary pairs of young M-dwarf multiple systems. The target systems are part of the astrometric monitoring AstraLux programme, surveying hundreds of M-dwarf systems for multiplicity and obtaining astrometric epochs for orbital constraints. Our new VLT/SINFONI data provides resolved spectral type classifications in the J, H, and K bands for seven of these low-mass M-dwarf binaries, which we determine by comparing them to empirical templates and examining the strength of water absorption in the K band. The medium resolution K-band spectra also allows us to derive effective temperatures for the individual components. All targets in the survey display several signs of youth, and some have kinematics similar to young moving groups, or low surface gravities which we determined from measuring equivalent widths of gravity sensitive alkali lines in the J band. Resolved photometry from our targets is also compared with isochrones from theoretical evolutionary models, further implying young ages. Dynamical masses will be provided from continued monitoring of these systems, which can be seen as emblematic binary benchmarks that may be used to calibrate evolutionary models for low-mass stars in the future.

Download Full-text

Dynamical Evolution of the Early Solar System

Annual Review of Astronomy and Astrophysics ◽

10.1146/annurev-astro-081817-052028 ◽

2018 ◽

Vol 56 (1) ◽

pp. 137-174 ◽

Cited By ~ 53

Author(s):

David Nesvorný

Keyword(s):

Solar System ◽

Kuiper Belt ◽

Dynamical Evolution ◽

Giant Planets ◽

Asteroid Belt ◽

Dynamical Instability ◽

Orbital Energy ◽

Interstellar Space ◽

Early Solar System ◽

Planetary Migration

Several properties of the Solar System, including the wide radial spacing of the giant planets, can be explained if planets radially migrated by exchanging orbital energy and momentum with outer disk planetesimals. Neptune's planetesimal-driven migration, in particular, has a strong advocate in the dynamical structure of the Kuiper belt. A dynamical instability is thought to have occurred during the early stages with Jupiter having close encounters with a Neptune-class planet. As a result of the encounters, Jupiter acquired its current orbital eccentricity and jumped inward by a fraction of an astronomical unit, as required for the survival of the terrestrial planets and from asteroid belt constraints. Planetary encounters also contributed to capture of Jupiter Trojans and irregular satellites of the giant planets. Here we discuss the dynamical evolution of the early Solar System with an eye to determining how models of planetary migration/instability can be constrained from its present architecture. Specifically, we review arguments suggesting that the Solar System may have originally contained a third ice giant on a resonant orbit between Saturn and Uranus. This hypothesized planet was presumably ejected into interstellar space during the instability. The Kuiper belt kernel and other dynamical structures in the trans-Neptunian region may provide evidence for the ejected planet. We favor the early version of the instability where Neptune migrated into the outer planetesimal disk within a few tens of millions of years after the dispersal of the protosolar nebula. If so, the planetary migration/instability was not the cause of the Late Heavy Bombardment. Mercury's orbit may have been excited during the instability.

Download Full-text

The Mass-Luminosity Relation From Binaries

Highlights of Astronomy ◽

10.1017/s1539299600021602 ◽

1998 ◽

Vol 11 (1) ◽

pp. 419-420

Author(s):

David W. Latham

Keyword(s):

Eclipsing Binaries ◽

M Dwarfs ◽

Direct Measurements ◽

Nearby Stars ◽

The Masses ◽

Stellar Masses ◽

M Dwarf ◽

Magnitude Difference ◽

Astrometric Binaries ◽

Better Than

What is known about the masses of main-sequence stars from the analysis of binary orbits? Double-lined eclipsing binaries are the main source of very precise stellar masses and radii (e.g. Andersen 1997), contributing more than 100 determinations with better than 2% precision over the range 0.6 to 20 Mʘ. For lower-mass stars we are forced to turn to nearby systems with astrometric orbits (e.g. Henry et al. 1993). Not only is the number of good mass determinations from such systems smaller, but also the precision is generally poorer. We are approaching an era when interferometers should have a major impact by supplying good astrometric orbits for dozens of double-lined systems. Already we are beginning to see the sorts of results to expect from this (e.g. Torres et al. 1997). Figure 1. Mass vs. absolute V magnitude for eclipsing binaries (circles) and nearby astrometric binaries (squares) Figure 1 is an updated version of a diagram presented by Henry et al. (1993, their Figure 2). It shows the general run of mass determinations from about 10 Mʘ down to the substellar limit near 0.075 Mʘ. Ninety of the points in Figure 1 are for eclipsing binary masses from Andersen’s review (1991) and are plotted as open circles. The results for eclipsing binaries published since 1991 are plotted as 30 filled circles, adopting the same limit of 2% for the mass precision. In most cases the uncertainties are similar to the size of the symbols. Especially noteworthy is the pair of new points for CM Draconis (Metcalfe et al. 1996) with masses near 0.25 Mʘ. Together with the points for YY Geminorum near 0.6 Mʘ, these are the only M dwarfs that have precise mass determinations. For the most part we are forced to rely on nearby stars with astrometric orbits, to fill in the M dwarf region of the diagram. We have used filled squares in Figure 1 for 29 such systems from Henry et al. (1993), updated using 14 new parallaxes from Hipparcos and 4 from the new Yale Parallax Catalog (1995). Gliese 508 is not included, because it is now known to be a triple, while Gliese 67AB, 570BC, and 623AB are not included because there are not yet any direct measurements of the V magnitude difference for these systems.

Download Full-text