Comets, Asteroids, and Dwarf Planets

2021 ◽  
pp. 65-156
Author(s):  
Jacques Crovisier ◽  
Marcello Fulchignoni
Keyword(s):  
Dwarf Planets

Trans-Neptunian Dwarf Planets

2021 ◽  
Author(s):  
Bryan Holler
Keyword(s):  
Solar System ◽  
Surface Composition ◽  
Planetary Science ◽  
Chemical Diversity ◽  
Asteroid Belt ◽  
Dynamical Structure ◽  
Forthcoming Article ◽  
Cold Temperatures ◽  
Dwarf Planets ◽  
Physical And Chemical

This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Planetary Science. Please check back later for the full article. The International Astronomical Union (IAU) officially recognizes five objects as dwarf planets: Ceres in the main asteroid belt between Mars and Jupiter; and Pluto, Eris, Haumea, and Makemake in the trans-Neptunian region beyond the orbit of Neptune. However, the definition used by the IAU applies to many other trans-Neptunian objects (TNOs) and can be summarized as any nonsatellite large enough to be rounded by its own gravity. Practically speaking, this means any nonsatellite with a diameter >400 km. In the trans-Neptunian region, there are more than 100 objects that satisfy this definition, based on published results and diameter estimates. The dynamical structure of the trans-Neptunian region records the migration history of the giant planets in the early days of the solar system. The semi-major axes, eccentricities, and orbital inclinations of TNOs across various dynamical classes provide constraints on different aspects of planetary migration. For many TNOs, the orbital parameters are all that is known about them, due to their large distances, small sizes, and low albedos. The TNO dwarf planets are a different story. These objects are large enough to be studied in more detail from ground- and space-based observatories. Imaging observations can be used to detect satellites and measure surface colors, while spectroscopy can be used to constrain surface composition. In this way, TNO dwarf planets not only help provide context for the dynamical evolution of the outer solar system, but also reveal the composition of the primordial solar nebula as well as the physical and chemical processes at work at very cold temperatures. The largest TNO dwarf planets, those officially recognized by the IAU, plus others such as Sedna, Quaoar, and Gonggong, are large enough to support volatile ices on their surfaces in the present day. These ices are able to exist as solids and gases on some TNOs, due to their sizes and surface temperatures (similar to water ice on Earth) and include N2 (nitrogen), CH4 (methane), and CO (carbon monoxide). A global atmosphere composed of these three species has been detected around Pluto, the largest TNO dwarf planet, with the possibility of local atmospheres or global atmospheres at perihelion for Eris and Makemake. The presence of nonvolatile species, such as H2O (water), NH3 (ammonia), and organics provide valuable information on objects that may be too small to retain volatile ices over the age of the solar system. In particular, large quantities of H2O mixed with NH3 points to ancient cryovolcanism caused by internal differentiation of ice from rock. Organic material, formed through radiation processing of surface ices such as CH4, records the radiation histories of these objects as well as providing clues to their primordial surface compositions. The dynamical, physical, and chemical diversity of the >100 TNO dwarf planets are key to understanding the formation of the solar system and subsequent evolution to its current state. Most of our knowledge comes from a small handful of objects, but we are continually expanding our horizons as additional objects are studied in more detail.

The formation and evolution of the solar system

2021 ◽  
Vol 03 (01) ◽  
pp. 85-87
Author(s):  
Türkanə Mirzəli qızı Əliyeva ◽  
◽  
Vəfa Əjdər qızı Qafarova ◽  
Keyword(s):  
Solar System ◽  
Kuiper Belt ◽  
New Horizons ◽  
T Tauri ◽  
Dwarf Planets ◽  
Celestial Bodies ◽  
Extensive Information ◽  
Formation And Evolution ◽  
Red Giant ◽  
Planet X

The article provides extensive information on the formation, evolution and structure of the solar system. It also discusses the planets of the solar system and the dwarf planets. Its noted that the Kuiper objects are the celestial bodies which belongs to the solar system. NASA's New Horizons spacecraft is currently helps studying four objects in the Kuiper belt. There is also talked about TTauri type stars. The article discusses the future transformation of the Sun from a Red Giant to a White Dwarf. Key words: Kuiper Belt, T Tauri Star, Dwarf Planets, Planet X

Kielemme kääpiösijoista

Virittäjä ◽  
2020 ◽  
Vol 124 (4) ◽  
Author(s):  
Jussi Ylikoski
Keyword(s):  
Borderline Case ◽  
Full Agreement ◽  
Clear Cut ◽  
Temporal Form ◽  
Case System ◽  
Dwarf Planets ◽  
Syntactic Properties ◽  
Traditional Paradigm ◽  
Instructive Case ◽  
Do So

Artikkelissa tarkastellaan suomen kielen sijataivutuksen ja adverbinjohdon rajaseutua. Suomen kieliopin kuvauksissa on tapana esittää 15 sijaa, joiden runsautta pidetään suomen kielen erityispiirteenä. Artikkelissa siirrytään perinteisen sijaparadigman marginaalin eli jopa niin sanottujen marginaalisten sijojen (abessiivin, instruktiivin ja komitatiivin) ulkopuolelle. Tarkastelun kohteena on vanhastaankin sijataivutuksen yhteydessä huomiota saanut väyliä ja välineitä ilmaiseva prolatiivi, mutta keskiössä ovat erityisesti isin-päätteiset temporaaliset ja (i)ttAin-päätteiset distributiiviset muodosteet, kuten iltaisin ja maanantaisin tai alueittain ja lajeittain. Tutkimusaineistona ovat laajat kirjoitettua nykysuomea edustavat korpukset. Kyllin laajoissa tutkimusaineistoissa sekä isin-temporaali että (i)ttAin-distributiivi paljastuvat verrattain produktiivisiksi muodostetyypeiksi: temporaalimuotojen (esim. kesäöisin, sapattisin) rinnalla etenkin distributiivimuodot ovat erittäin monikäyttöisiä (kyläkunnittain, nuorkauppakamareittain, tyylipiirteittäin). Erityistä huomiota saavat muodosteiden syntaktiset ominaisuudet, joiden valossa temporaali ja distributiivi – ja myös prolatiivi – poikkeavat tavanomaisista adverbeista, jollaisina niitä perinteisesti on pidetty. Mahdollisia ovat muun muassa relatiivilauseet (kirjeitse, jossa – –, maanantaisin, jotka – –), genetiiviattribuutit (elokuun lauantaisin, Suomen kunnittain) ja eräät taipumattomat määritteet (joka maanantaisin, koko kyläkunnittain). Uusi havainto on myös temporaali- ja distributiivimuotojen kyky saada instruktiivimuotoisia adjektiiviattribuutteja: lausekkeet satunnaisin viikonloppuisin ja tietyin aihealueittain muistuttavat marginaalisuudessaankin sijamuotoja ja etenkin komitatiivia (omin ~ omine lupineen). Artikkelissa esitetään, että sijajärjestelmämme kuvauksen rajapintaa voisi laajentaa eräänlaisilla kääpiösijoilla samaan tapaan kuin eräitä aurinkokuntamme jäseniä voidaan luonnehtia kääpiöplaneetoiksi, vaikka ne eivät varsinaiseen planeetan määritelmään sopisikaan.   On Finnish dwarf cases: prolative, temporal and distributive The article discusses the borderland between nominal case inflection and adverb derivation in Finnish. Finnish grammars customarily present a case system of fifteen cases. The present article takes a step outside of the most marginal cases (abessive, instructive and comitative) within the traditional paradigm. In addition to observations on the so-called prolative, which has at times been considered a borderline case, the main focus of the study is on two kinds of formations traditionally regarded as denominal adverbs. The previously under-described formations ending in -isin have a repetitive temporal meaning (e.g., iltaisin ‘in the evenings’) and those ending in -(i)ttain/-(i)ttäin are distributive forms (e.g., maittain ‘by country’). Based on data drawn from large corpora of modern written Finnish, the temporal form -isin and particularly the distributive forms -(i)ttain/-(i)ttäin appear to be rather productive morphological categories. Special attention is given to the syntactic properties of these formations, as the data shows that not only do the case-like prolative forms differ from ordinary adverbs, but the temporal and distributive forms do so too. The author argues that the formations in question are not fully denominal forms, rather they reveal many features characteristic of nouns: they may be accompanied by postmodifying relative clauses as well as genitive and adjectival modifiers. In the absence of the full agreement typical of Finnish adjectival modifiers, the associated adjectives occur in the instructive case (e.g., satunnais-in viikonloppu-isin [random-pl.instr weekend-temp] ‘on random weekends’ and tiety-in aihealue-ittain [certain-pl.instr thematic.area-distr] ‘by certain thematic areas’), which in turn makes the temporal and distributive forms resemble those of the comitative case. The article shows that the inflection–derivation interface of the Finnish noun is far from clear-cut. On the basis of the findings presented in this study, the author asserts that our understanding of the Finnish case system could be advanced by introducing the concept of the “dwarf case”, analogous with that of dwarf planets, which are members of the Solar System and share many features with planets despite not being true planets themselves.

scholarly journals Red Optical Planet Survey: A radial velocity search for low mass M dwarf planets

2013 ◽  
Vol 47 ◽  
pp. 05002
Author(s):  
J.R. Barnes ◽  
J.S. Jenkins ◽  
H.R.A. Jones ◽  
P. Rojo ◽  
P. Arriagada ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Dwarf Planets ◽  
Low Mass ◽  
M Dwarf

scholarly journals An Astrobiological Experiment to Explore the Habitability of Tidally Locked M-Dwarf Planets

2012 ◽  
Vol 8 (S293) ◽  
pp. 192-196
Author(s):  
Daniel Angerhausen ◽  
Haley Sapers ◽  
Eugenio Simoncini ◽  
Stefanie Lutz ◽  
Marcelo da Rosa Alexandre ◽  
...  
Keyword(s):  
Academic Research ◽  
Environmental Parameters ◽  
Climate Simulation ◽  
Habitable Zone ◽  
Dwarf Stars ◽  
Dwarf Planets ◽  
Late Type Star ◽  
M Dwarf Stars ◽  
M Dwarf ◽  
Simulation Chamber

AbstractWe present a summary of a three-year academic research proposal drafted during the Sao Paulo Advanced School of Astrobiology (SPASA) to prepare for upcoming observations of tidally locked planets orbiting M-dwarf stars. The primary experimental goal of the suggested research is to expose extremophiles from analogue environments to a modified space simulation chamber reproducing the environmental parameters of a tidally locked planet in the habitable zone of a late-type star. Here we focus on a description of the astronomical analysis used to define the parameters for this climate simulation.

scholarly journals Can we detect aurora in exoplanets orbiting M dwarfs?

2019 ◽  
Vol 488 (1) ◽  
pp. 633-644 ◽  
Author(s):  
A A Vidotto ◽  
N Feeney ◽  
J H Groh
Keyword(s):  
Solar System ◽  
Radio Emission ◽  
Stellar Wind ◽  
Engineering Calculation ◽  
M Dwarfs ◽  
Radio Detection ◽  
Dwarf Planets ◽  
M Dwarf ◽  
Host Stars ◽  
New Instruments

ABSTRACT New instruments and telescopes, such as SPIRou, CARMENES, and Transiting Exoplanet Survey Satellite (TESS), will increase manyfold the number of known planets orbiting M dwarfs. To guide future radio observations, we estimate radio emission from known M dwarf planets using the empirical radiometric prescription derived in the Solar system, in which radio emission is powered by the wind of the host star. Using solar-like wind models, we find that the most promising exoplanets for radio detections are GJ 674 b and Proxima b, followed by YZ Cet b, GJ 1214 b, GJ 436 b. These are the systems that are the closest to us (<10 pc). However, we also show that our radio fluxes are very sensitive to the unknown properties of winds of M dwarfs. So, which types of winds would generate detectable radio emission? In a ‘reverse engineering’ calculation, we show that winds with mass-loss rates $\dot{M} \gtrsim \kappa _{\rm sw} /u_{\rm sw}^3$ would drive planetary radio emission detectable with present-day instruments, where usw is the local stellar wind velocity and κsw is a constant that depends on the size of the planet, distance, and orbital radius. Using observationally constrained properties of the quiescent winds of GJ 436 and Proxima Cen, we conclude that it is unlikely that GJ 436 b and Proxima b would be detectable with present-day radio instruments, unless the host stars generate episodic coronal mass ejections. GJ 674 b, GJ 876 b, and YZ Cet b could present good prospects for radio detection, provided that their host stars’ winds have $\dot{M} u_{\rm sw}^{3} \gtrsim 1.8\times 10^{-4} \, {\rm M}_\odot \,{\rm yr}^{-1}\, ({\rm km\,s^{-1}})^{3}$.

scholarly journals Calibration of the angular momenta of the minor planets in the solar system

2019 ◽  
Vol 630 ◽  
pp. A68 ◽  
Author(s):  
Jian Li ◽  
Zhihong Jeff Xia ◽  
Liyong Zhou
Keyword(s):  
Angular Momentum ◽  
Solar System ◽  
Total Angular Momentum ◽  
Physical Parameters ◽  
Minor Planets ◽  
The Sun ◽  
Relative Angle ◽  
Angular Momenta ◽  
Dwarf Planets ◽  
Invariable Plane

Aims. We aim to determine the relative angle between the total angular momentum of the minor planets and that of the Sun-planets system, and to improve the orientation of the invariable plane of the solar system. Methods. By utilizing physical parameters available in public domain archives, we assigned reasonable masses to 718 041 minor planets throughout the solar system, including near-Earth objects, main belt asteroids, Jupiter trojans, trans-Neptunian objects, scattered-disk objects, and centaurs. Then we combined the orbital data to calibrate the angular momenta of these small bodies, and evaluated the specific contribution of the massive dwarf planets. The effects of uncertainties on the mass determination and the observational incompleteness were also estimated. Results. We determine the total angular momentum of the known minor planets to be 1.7817 × 1046 g cm2 s−1. The relative angle α between this vector and the total angular momentum of the Sun-planets system is calculated to be about 14.74°. By excluding the dwarf planets Eris, Pluto, and Haumea, which have peculiar angular momentum directions, the angle α drops sharply to 1.76°; a similar result applies to each individual minor planet group (e.g., trans-Neptunian objects). This suggests that, without these three most massive bodies, the plane perpendicular to the total angular momentum of the minor planets would be close to the invariable plane of the solar system. On the other hand, the inclusion of Eris, Haumea, and Makemake can produce a difference of 1254 mas in the inclination of the invariable plane, which is much larger than the difference of 9 mas induced by Ceres, Vesta, and Pallas as found previously. By taking into account the angular momentum contributions from all minor planets, including the unseen ones, the orientation improvement of the invariable plane is larger than 1000 mas in inclination with a 1σ error of ∼50−140 mas.

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