8. Moons in other planetary systems

2015 ◽  
pp. 137-139
Author(s):  
David A. Rothery
Keyword(s):  
Solar System ◽  
Hydrothermal Vents ◽  
Planetary Systems ◽  
Direct Imaging ◽  
Microbial Life ◽  
Good Place ◽  
The Galaxy ◽  
Made In

The first definite discovery of a planet around another star—an ‘exoplanet’—was made in 1995. We now know of more than 1,000 stars with exoplanets. In our Solar System, moons are considerably more numerous than planets, so it would be surprising if exomoons did not outnumber exoplanets. Only a few exceptional exoplanets have been seen by direct imaging and any exomoons are presently well below the visibility threshold. ‘Moons in other planetary systems: exomoons’ considers why exomoons matter. If hydrothermal vents on ocean floors really are a good place for life to begin, then icy exomoons with internal oceans throughout the galaxy could host microbial life.

The Long View of Planetary Systems

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Milky Way ◽  
Planetary Systems ◽  
Giant Planets ◽  
Milky Way Galaxy ◽  
Population Statistics ◽  
The Past ◽  
General Terms ◽  
The Galaxy ◽  
The Universe

How many planetary systems formed before our’s did, and how many will form after? How old is the average exoplanet in the Galaxy? When did the earliest planets start forming? How different are the ages of terrestrial and giant planets? And, ultimately, what will the fate be of our Solar System, of the Milky Way Galaxy, and of the Universe around us? We cannot know the fate of individual exoplanets with great certainty, but based on population statistics this chapter sketches the past, present, and future of exoworlds and of our Earth in general terms.

scholarly journals Visions of Human Futures in Space and SETI

2017 ◽  
Author(s):  
Jason T. Wright ◽  
Michael P. Oman-Reagan
Keyword(s):  
Solar System ◽  
Science Fiction ◽  
Dark Matter Particle ◽  
Short Term ◽  
National Science ◽  
The Galaxy ◽  
Near Future ◽  
Far Future ◽  
Made In

We discuss how visions for the futures of humanity in space and SETI are intertwined, and are shaped by prior work in the fields and by science fiction. This appears in the language used in the fields, and in the sometimes implicit assumptions made in discussions of them. We give examples from articulations of the so-called Fermi Paradox, discussions of the settlement of the Solar System (in the near future) and the Galaxy (in the far future), and METI. We argue that science fiction, especially the campy variety, is a significant contributor to the ‘giggle factor’ that hinders serious discussion and funding for SETI and Solar System settlement projects. We argue that humanity's long-term future in space will be shaped by our short-term visions for who goes there and how. Because of the way they entered the fields, we recommend avoiding the term ‘colony’ and its cognates when discussing the settlement of space, as well as other terms with similar pedigrees. We offer examples of science fiction and other writing that broaden and challenge our visions of human futures in space and SETI. In an appendix, we use an analogy with the well-funded and relatively uncontroversial searches for the dark matter particle to argue that SETI's lack of funding in the national science portfolio is primarily a problem of perception, not inherent merit.Also on arXiv: https://arxiv.org/abs/1708.05318Please cite this version:Wright, Jason T., and Michael P. Oman-Reagan. “Visions of Human Futures in Space and SETI.” International Journal of Astrobiology, 2017, 1–12. doi:10.1017/S1473550417000222.

Epilogue: Paradigms, Problems, and Predictions

2017 ◽  
Author(s):  
John Chambers ◽  
Jacqueline Mitton
Keyword(s):  
Solar System ◽  
Planetary Systems ◽  
Planetary Science ◽  
Good Time ◽  
Science Program ◽  
The Galaxy ◽  
Recent Developments ◽  
Powerful Stimulus ◽  
Rapid Pace ◽  
Over Time

This concluding chapter talks about how astronomers and space agencies in dozens of countries are helping to see the solar system as never before, transforming points of light into real worlds, and even bringing samples of those worlds back to Earth. At the same time, the stunning discovery of hundreds of other planetary systems in the galaxy has provided a powerful stimulus to understand how planetary systems form and evolve, and to find out what makes one system different from another. Moreover, in 2010, NASA announced its latest science plan. One of the key goals for NASA's future planetary science program is to learn how the Sun's family began and how it has changed over time. The chapter argues that the rapid pace of recent developments makes now a good time to take stock of what scholars know, even though the story is still incomplete.

scholarly journals Turning solar systems into extrasolar planetary systems in stellar clusters

2010 ◽  
Vol 6 (S276) ◽  
pp. 304-307
Author(s):  
Melvyn B. Davies
Keyword(s):  
Solar System ◽  
Planetary System ◽  
Large Fraction ◽  
Planetary Systems ◽  
Single Star ◽  
Solar Systems ◽  
Close Encounters ◽  
Eccentric Orbits ◽  
The Galaxy ◽  
Hostile Environments

AbstractMany stars are formed in some form of cluster or association. These environments can have a much higher number density of stars than the field of the galaxy. Such crowded places are hostile environments: a large fraction of initially single stars will undergo close encounters with other stars or exchange into binaries. We describe how such close encounters and exchange encounters will affect the properties of a planetary system around a single star. We define singletons as single stars which have never suffered close encounters with other stars or spent time within a binary system. It may be that planetary systems similar to our own solar system can only survive around singletons. Close encounters or the presence of a stellar companion will perturb the planetary system, leading to strong planet-planet interactions, often leaving planets on tighter and more eccentric orbits. Thus, planetary systems which initially resembled our own solar system may later more closely resemble the observed extrasolar planetary systems.

scholarly journals Fly-by encounters between two planetary systems I: Solar system analogues

2019 ◽  
Vol 488 (1) ◽  
pp. 1366-1376 ◽  
Author(s):  
Daohai Li ◽  
Alexander J Mustill ◽  
Melvyn B Davies
Keyword(s):  
Solar System ◽  
Planetary System ◽  
Planetary Systems ◽  
Open Clusters ◽  
Giant Planets ◽  
Direct Imaging ◽  
Solar Mass ◽  
Close Encounters ◽  
Large Numbers

ABSTRACTStars formed in clusters can encounter other stars at close distances. In typical open clusters in the Solar neighbourhood containing hundreds or thousands of member stars, 10–20 per cent of Solar-mass member stars are expected to encounter another star at distances closer than 100 au. These close encounters strongly perturb the planetary systems, directly causing ejection of planets or their capture by the intruding star, as well as exciting the orbits. Using extensive N-body simulations, we study such fly-by encounters between two Solar system analogues, each with four giant planets from Jupiter to Neptune. We quantify the rates of loss and capture immediately after the encounter, e.g. the Neptune analogue is lost in one in four encounters within 100 au, and captured by the flying-by star in 1 in 12 encounters. We then perform long-term (up to 1 Gyr) simulations investigating the ensuing post-encounter evolution. We show that large numbers of planets are removed from systems due to planet–planet interactions and that captured planets further enhance the system instability. While encounters can initially leave a planetary system containing more planets by inserting additional ones, the long-term instability causes a net reduction in planet number. A captured planet ends up on a retrograde orbit in half of the runs in which it survives for 1Gyr; also, a planet bound to its original host star but flipped during the encounter may survive. Thus, encounters between planetary systems are a channel to create counter-rotating planets, This would happen in around 1 per cent of systems, and such planets are potentially detectable through astrometry or direct imaging.

scholarly journals Visions of human futures in space and SETI

2017 ◽  
Vol 17 (2) ◽  
pp. 177-188 ◽  
Author(s):  
Jason T. Wright ◽  
Michael P. Oman-Reagan
Keyword(s):  
Solar System ◽  
Science Fiction ◽  
Dark Matter Particle ◽  
Short Term ◽  
National Science ◽  
The Galaxy ◽  
Near Future ◽  
Far Future ◽  
Made In

AbstractWe discuss how visions for the futures of humanity in space and SETI are intertwined, and are shaped by prior work in the fields and by science fiction. This appears in the language used in the fields, and in the sometimes implicit assumptions made in discussions of them. We give examples from articulations of the so-called Fermi Paradox, discussions of the settlement of the Solar System (in the near future) and the Galaxy (in the far future), and METI. We argue that science fiction, especially the campy variety, is a significant contributor to the ‘giggle factor’ that hinders serious discussion and funding for SETI and Solar System settlement projects. We argue that humanity's long-term future in space will be shaped by our short-term visions for who goes there and how. Because of the way they entered the fields, we recommend avoiding the term ‘colony’ and its cognates when discussing the settlement of space, as well as other terms with similar pedigrees. We offer examples of science fiction and other writing that broaden and challenge our visions of human futures in space and SETI. In an appendix, we use an analogy with the well-funded and relatively uncontroversial searches for the dark matter particle to argue that SETI's lack of funding in the national science portfolio is primarily a problem of perception, not inherent merit.

scholarly journals The Drake equation may need new factors based on peculiarities of planets of Sun-like stars

2004 ◽  
Vol 202 ◽  
pp. 458-461 ◽  
Author(s):  
L. V. Ksanfomality
Keyword(s):  
Solar System ◽  
Planetary Systems ◽  
Habitable Zone ◽  
Unique Object ◽  
The Galaxy ◽  
The Mean ◽  
Limited Statistic

N = RsfpneflfifcL. This well known Drake equation denoting the number N of civilizations in the Galaxy, includes a factor fp that is the fraction of stars that have planetary systems, and another factor ne that is the mean number of planets suitable for life. The latter is usually understood as the number of planets within the habitable zone. When the Solar system remained a unique object of its kind the sense of fp and ne seemed to be clear. There is now a limited statistic in hand about the features of other planetary systems, permitting a rough estimation of fp and ne (based on the list of 32 star companions, compiled by G. Marcy, 14.02.2000).

From One to Astronomical

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Scientific Method ◽  
State Of The Art ◽  
Planetary Systems ◽  
The Earth ◽  
The Galaxy ◽  
Fictional Worlds ◽  
Recent Insight

Where centuries ago one could be burned at the stake for speculating about distant worlds, the modern scientific method has made us realize that there are planetary systems around most of the over a hundred billion stars in the Galaxy. Learning that the Earth was not the center of the Solar System represented a true revolution in our thinking, but the recent insight that the Solar System is but one of an immense number of similar systems was smoothly adopted by our culture, which had already been exposed to many fictional worlds over the preceding dedades. This introductory chapter describes these changes, woven into the story of how astrophysics has grown from the work of a few isolated individuals into a globe-spanning, fast-publishing enterprise with state-of-the-art observatories, from master–pupil teaching to university-based education, and from learning from often ancient books to modern observation-based investigations.

scholarly journals Chemical Enrichment of the Solar System by Stellar Ejecta

2012 ◽  
Vol 10 (H16) ◽  
pp. 161-161
Author(s):  
Sun Kwok
Keyword(s):  
Silicon Carbide ◽  
Organic Matter ◽  
Solar System ◽  
Aliphatic Compounds ◽  
Chemical Enrichment ◽  
Chemical Structures ◽  
Evolved Stars ◽  
Insoluble Organic Matter ◽  
The Galaxy ◽  
Made In

AbstractSpectroscopic observations of evolved stars have shown signatures of aromatic and aliphatic compounds. This suggests that complex organics with chemical structures similar to those of insoluble organic matter (IOM) found in carbonaceous meteorites are made in stars. This raises the possibility that in addition to known pre-solar grains such as silicon carbide, organic star dust may also have traveled across the Galaxy to the Solar System.

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