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تسجيل مستخدم جديدSolar System Physics for Exoplanet Research
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Over the past three decades, we have witnessed one of the great revolutions in our understanding of the cosmos - the dawn of the Exoplanet Era. Where once we knew of just one planetary system (the Solar system), we now know of thousands, with new systems being announced on a weekly basis. Of the thousands of planetary systems we have found to date, however, there is only one that we can study up-close and personal - the Solar system. In this review, we describe our current understanding of the Solar system for the exoplanetary science community - with a focus on the processes thought to have shaped the system we see today. In section one, we introduce the Solar system as a single well studied example of the many planetary systems now observed. In section two, we describe the Solar systems small body populations as we know them today - from the two hundred and five known planetary satellites to the various populations of small bodies that serve as a reminder of the systems formation and early evolution. In section three, we consider our current knowledge of the Solar systems planets, as physical bodies. In section four, we discuss the research that has been carried out into the Solar systems formation and evolution, with a focus on the information gleaned as a result of detailed studies of the systems small body populations. In section five, we discuss our current knowledge of planetary systems beyond our own - both in terms of the planets they host, and in terms of the debris that we observe orbiting their host stars. As we learn ever more about the diversity and ubiquity of other planetary systems, our Solar system will remain the key touchstone that facilitates our understanding and modelling of those newly found systems, and we finish section five with a discussion of the future surveys that will further expand that knowledge.
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Exoplanet surveys have confirmed one of humanitys (and all teenagers) worst fears: we are weird. If our Solar System were observed with present-day Earth technology -- to put our system and exoplanets on the same footing -- Jupiter is the only planet
that would be detectable. The statistics of exo-Jupiters indicate that the Solar System is unusual at the ~1% level among Sun-like stars (or ~0.1% among all stars). But why are we different? Successful formation models for both the Solar System and exoplanet systems rely on two key processes: orbital migration and dynamical instability. Systems of close-in super-Earths or sub-Neptunes require substantial radial inward motion of solids either as drifting mm- to cm-sized pebbles or migrating Earth-mass or larger planetary embryos. We argue that, regardless of their formation mode, the late evolution of super-Earth systems involves migration into chains of mean motion resonances, generally followed by instability when the disk dissipates. This pattern is likely also ubiquitous in giant planet systems. We present three models for inner Solar System formation -- the low-mass asteroid belt, Grand Tack, and Early Instability models -- each invoking a combination of migration and instability. We identify bifurcation points in planetary system formation. We present a series of events to explain why our Solar System is so weird. Jupiters core must have formed fast enough to quench the growth of Earths building blocks by blocking the flux of inward-drifting pebbles. The large Jupiter/Saturn mass ratio is rare among giant exoplanets but may be required to maintain Jupiters wide orbit. The giant planets instability must have been gentle, with no close encounters between Jupiter and Saturn, also unusual in the larger (exoplanet) context. Our Solar System system is thus the outcome of multiple unusual, but not unheard of, events.
Exocomets are small bodies releasing gas and dust which orbit stars other than the Sun. Their existence was first inferred from the detection of variable absorption features in stellar spectra in the late 1980s using spectroscopy. More recently, they
have been detected through photometric transits from space, and through far-IR/mm gas emission within debris disks. As (exo)comets are considered to contain the most pristine material accessible in stellar systems, they hold the potential to give us information about early stage formation and evolution conditions of extra Solar Systems. In the Solar System, comets carry the physical and chemical memory of the protoplanetary disk environment where they formed, providing relevant information on processes in the primordial solar nebula. The aim of this paper is to compare essential compositional properties between Solar System comets and exocomets. The paper aims to highlight commonalities and to discuss differences which may aid the communication between the involved research communities and perhaps also avoid misconceptions. Exocomets likely vary in their composition depending on their formation environment like Solar System comets do, and since exocomets are not resolved spatially, they pose a challenge when comparing them to high fidelity observations of Solar System comets. Observations of gas around main sequence stars, spectroscopic observations of polluted white dwarf atmospheres and spectroscopic observations of transiting exocomets suggest that exocomets may show compositional similarities with Solar System comets. The recent interstellar visitor 2I/Borisov showed gas, dust and nuclear properties similar to that of Solar System comets. This raises the tantalising prospect that observations of interstellar comets may help bridge the fields of exocomet and Solar System comets.
The presence of excesses of short-lived radionuclides in the early solar system evidenced in meteorites has been taken as testament to close encounters with exotic nucleosynthetic sources, including supernovae or AGB stars. An analysis of the likelih
oods associated with different sources of these extinct nuclides in the early solar system indicates that rather than being exotic, their abundances were typical of star-forming regions like those observed today in the Galaxy. The radiochemistry of the early solar system is therefore unexceptional, being the consequence of extensive averaging of molecular cloud solids.
We have carried out an intensive study of photometric (Kepler Mission) and spectroscopic data on the system Kepler-2 (HAT-P-7A) using the dedicated software WinFitter. The mean individual data-point error of the normalized flux values for this system
is 0.00015, leading to the models specification for the mean reference flux to an accuracy of $sim$0.5 ppm. This testifies to the remarkably high accuracy of the binned data-set, derived from over 1.8 million individual observations. Spectroscopic data are reported with the similarly high-accuracy radial velocity amplitude measure of $sim$2 m s$^{-1}$. The analysis includes discussion of the fitting quality and model adequacy. Our derived absolute parameters for Kepler-2 are as follows: $M_p$ (Jupiter) 1.80 $pm$ 0.13; $R_{star}$ 1.46 $pm 0.08 times 10^6$ km; $R_p$ 1.15 $pm 0.07 times 10^5$ km. These values imply somewhat larger and less condensed bodies than previously catalogued, but within reasonable error estimates of such literature parameters. We find also tidal, reflection and Doppler effect parameters, showing that the optimal model specification differs slightly from a `cleaned model that reduces the standard deviation of the $sim$3600 binned light curve points to less than 0.9 ppm. We consider these slight differences, making comparisons with the hot-jupiter systems Kepler-1 (TrES-2) and 13.
We describe the contents and functionality of the NASA Exoplanet Archive, a database and tool set funded by NASA to support astronomers in the exoplanet community. The current content of the database includes interactive tables containing properties
of all published exoplanets, Kepler planet candidates, threshold-crossing events, data validation reports and target stellar parameters, light curves from the Kepler and CoRoT missions and from several ground-based surveys, and spectra and radial velocity measurements from the literature. Tools provided to work with these data include a transit ephemeris predictor, both for single planets and for observing locations, light curve viewing and normalization utilities, and a periodogram and phased light curve service. The archive can be accessed at http://exoplanetarchive.ipac.caltech.edu.
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