Persistent hazardous environments around stars older than the Sun

2006 ◽  
Vol 5 (3) ◽  
pp. 187-190 ◽  
Author(s):  
J.S. Greaves
Keyword(s):  
Solar System ◽  
Kuiper Belt ◽  
The Sun ◽  
Hazardous Environments ◽  
Debris Particles ◽  
Recovery Times ◽  
Nearby Stars ◽  
History Of ◽  
Large Telescopes ◽  
Long Timescales

Collisions amongst comets create belts of orbiting debris and, by using submillimetre wavelength observations, these collision zones can be imaged around nearby stars. An image of the closest Solar analogue, τ Ceti, shows that it possesses at least 20 times the content of the outer Solar System in cool debris particles. The inferred population of parent colliders is around 1 M[oplus ], also much larger than in the Sun's Kuiper Belt of comets. This system represents a different evolutionary outcome for a Sun-like star, with no Jupiter-like planet but many cometary bodies, and thus a potentially heavy and prolonged history of impacts on any inner terrestrial planets. Since τ Ceti is 10 Gyr old, life would have had to deal with massive bombardment over very long timescales. Furthermore, impactors in the 10 km-upwards class could arrive at intervals of 1 Myr or less, longer than recovery times on Earth, and so similar biology is unlikely. It is presently unknown whether nearby stars typically have comet belts similar to that of the Sun or of τ Ceti; extrapolations of existing data suggest many stars could be at least 2–5 times above the Solar debris level. Future large telescopes will be able to probe down to Solar System levels of cometary debris.

scholarly journals Investigating the dynamical history of the interstellar object ’Oumuamua

2018 ◽  
Vol 610 ◽  
pp. L11 ◽  
Author(s):  
Piotr A. Dybczyński ◽  
Małgorzata Królikowska
Keyword(s):  
Solar System ◽  
Numerical Results ◽  
The Sun ◽  
Distant Source ◽  
Kinematic Data ◽  
Close Encounters ◽  
Nearby Stars ◽  
History Of ◽  
Open Question

Here we try to find the origin of 1I/2017 U1 ’Oumuamua, the first interstellar object recorded inside the solar system. To this aim, we searched for close encounters between ’Oumuamua and all nearby stars with known kinematic data during their past motion. We had checked over 200 thousand stars and found just a handful of candidates. If we limit our investigation to within a 60 pc sphere surrounding the Sun, then the most probable candidate for the ’Oumuamua parent stellar habitat is the star UCAC4 535-065571. However GJ 876 is also a favourable candidate. However, the origin of ’Oumuamua from a much more distant source is still an open question. Additionally, we found that the quality of the original orbit of ’Oumuamua is accurate enough for such a study and that none of the checked stars had perturbed its motion significantly. All numerical results of this research are available in the appendix.

scholarly journals The Principle of Least Interaction Action

1974 ◽  
Vol 3 ◽  
pp. 489-489
Author(s):  
M. W. Ovenden
Keyword(s):  
Solar System ◽  
Planetary System ◽  
Satellite System ◽  
Asteroid Belt ◽  
Correct Prediction ◽  
The Sun ◽  
Approximate Methods ◽  
Satellites Of Jupiter ◽  
History Of ◽  
Minimum Interaction

AbstractThe intuitive notion that a satellite system will change its configuration rapidly when the satellites come close together, and slowly when they are far apart, is generalized to ‘The Principle of Least Interaction Action’, viz. that such a system will most often be found in a configuration for which the time-mean of the action associated with the mutual interaction of the satellites is a minimum. The principle has been confirmed by numerical integration of simulated systems with large relative masses. The principle lead to the correct prediction of the preference, in the solar system, for nearly-commensurable periods. Approximate methods for calculating the evolution of an actual satellite system over periods ˜ 109 yr show that the satellite system of Uranus, the five major satellites of Jupiter, and the five planets of Barnard’s star recently discovered, are all found very close to their respective minimum interaction distributions. Applied to the planetary system of the Sun, the principle requires that there was once a planet of mass ˜ 90 Mθ in the asteroid belt, which ‘disappeared’ relatively recently in the history of the solar system.

scholarly journals The early history of the earth

1988 ◽  
Vol 7 (1) ◽  
pp. 38-47
Author(s):  
C. P. Snyman
Keyword(s):  
Solar System ◽  
Laws Of Nature ◽  
Early History ◽  
The Sun ◽  
Natural Phenomena ◽  
The Earth ◽  
History Of ◽  
By Products

In view of the principle of actualism the early history of the earth must be explained on the basis of present-day natural phenomena and the basic Laws of Nature. The study of the solar system leads to the conclusion that the planets were formed as by-products when the sun developed from a rotating cloud of cosmic gas and dust. The protoplanets or planetesimals could have accreted as a result of mutual collisions, during which they could have become partly molten so that they could differentiate into a crust, a mantle and a core on the basis of differences in density.

scholarly journals IX. On the tidal friction of a planet attended by several satellites, and on the evolution of the solar system

1881 ◽  
Vol 172 ◽  
pp. 491-535 ◽  
Keyword(s):  
Solar System ◽  
Central Body ◽  
The Sun ◽  
Tidal Friction ◽  
The Earth ◽  
History Of ◽  
The Subject ◽  
Complete Investigation

In previous papers on the subject of tidal friction I have confined my attention principally to the case of a planet attended by a single satellite. But in order to make the investigation applicable to the history of the earth and moon it was necessary to take notice of the perturbation of the sun. In consequence of the largeness of the sun’s mass it was not there requisite to make a complete investigation of the theory of a planet attended by a pair of satellites. In the first part of this paper the theory of the tidal friction of a central body attended by any number of satellites is considered.

scholarly journals Dynamics of Comets: Recent Developments and New Challenges

1994 ◽  
Vol 160 ◽  
pp. 223-240
Author(s):  
Julio A. Fernández
Keyword(s):  
Solar System ◽  
Inner Core ◽  
Galactic Disk ◽  
Kuiper Belt ◽  
Oort Cloud ◽  
Tidal Force ◽  
Giant Molecular Clouds ◽  
Recent Developments ◽  
Large Telescopes ◽  
Classical Picture

There is a broad consensus that long-period comets come from a huge reservoir surrounding the solar system, as proposed originally by Oort. Yet, the classical picture of the Oort cloud has substantially changed during the last decade. In addition to passing stars, the tidal force of the galactic disk and giant molecular clouds have also been identified as major perturbers of the Oort cloud. In particular, the latter may be responsible for limiting the size of the stable Oort cloud to no more than ≈ 104AU, i.e. about one tenth of the classical Oort's radius.Most comets are injected into the planetary region by the quasi-steady action of the tidal force of the galactic disk. The concentration of aphelion points of dynamically young comets toward mid-galactic latitudes is a consequence of its dominant influence. The frequency of comet passages into the inner planetary region could experience significant fluctuations with time as the Oort cloud meets random strong perturbers. The observed ordered pattern of most comet aphelia, associated with the galactic structure, argues against a recent strong perturbation of the Oort cloud.The origin of the Jupiter family has become another point of intense debate. Jupiter family comets may come from a transneptunian comet belt -the Kuiper belt- from where they can reach the planetary region through chaotic motion. The Kuiper belt has become accessible to large telescopes, as shown by the recent discoveries of 1992QB1 and 1993FW, possibly belt members. The major challenge will be to explore the region usually inaccessible to external perturbers that goes from ~30 AU to a few thousand AU. A significant mass may have been locked there from the beginnings of the solar system, giving rise to an inner core that feeds the outer or classical Oort cloud. Our aim will be to briefly discuss some of the topics summarized here.

scholarly journals Helium and Hydrogen of the Local Interstellar Medium Observed in the Vicinity of the Sun

1984 ◽  
Vol 81 ◽  
pp. 3-23 ◽  
Author(s):  
Jean-Loup Bertaux
Keyword(s):  
Solar System ◽  
Interstellar Medium ◽  
Galactic Plane ◽  
Intermediate Phase ◽  
Substantial Part ◽  
The Sun ◽  
Degree Of Ionization ◽  
Helium Atoms ◽  
Space Instruments ◽  
Nearby Stars

AbstractThe Sun is moving in respect to the nearby stars with a velocity of 20 km.s-1 in the direction of the Apex, α = 271° and δ = 30° (celestial coordinates). As the lights of a car illuminate the water droplets when driving in the fog, the Sun illuminates the Hydrogen and helium atoms of the interstellar medium which it travels through. As a result, the sun and the whole solar system are imbedded in a glow of the resonance lines of hydrogen (H Lyman α ; 121.6 nm) and helium (58.4 nm), which have been studied by several space instruments in the last 14 years.From the intensity distribution of the glow in the solar system, one can derive the density of H and He in the L1SM and the direction of the relative motion between the sun and the LISM in the very vicinity of the sun. The velocity module Vw and the LISM temperature T are more adequately found from a measurement of the Lyman α line shape, which is an image of the velocity distribution of H atoms.A summary of results will be presented, together with a discussion of the methods of interpretation and their difficulties. The vector is found to be 20 ± 1 km.s-1 in the direction α = 254 ± 3°, δ = - 17 ± 3°, quite different from the Apex direction. This means that the LISM is moving also in respect to the local frame of reference giving rise to the socalled Interstellar Wind. This wind blows in the galactic plane at 16 km.s-1, in the direction , significantly different from the direction found by interstellar absorption lines on stars within ≃ 100 pc, pointing to a local significance of this flow. The temperature of the LISM is T = 8,000 ± 1,000 K, the density n (H) ≃ 0.04 to 0.06 cm-3, and the helium density n (He) ≃ 0.015 to 0.020. The high helium/hydrogen ratio, in respect to the cosmological ratio, would imply that a substantial part of the hydrogen is ionized. Temperature, density and degree of ionization of the LISM are suggesting that the sun is now in an intermediate phase of the interstellar medium, at the Interface between a hot and tenuous gas, and a dense and cold cloud of gas.

scholarly journals History of the solar nebula from meteorite paleomagnetism

2021 ◽  
Vol 7 (1) ◽  
pp. eaba5967
Author(s):  
Benjamin P. Weiss ◽  
Xue-Ning Bai ◽  
Roger R. Fu
Keyword(s):  
Solar System ◽  
Solar Nebula ◽  
Protoplanetary Disks ◽  
Outer Solar System ◽  
The Sun ◽  
Planetary Formation ◽  
Solar System Formation ◽  
Astronomical Observations ◽  
Accretion Rates ◽  
History Of

We review recent advances in our understanding of magnetism in the solar nebula and protoplanetary disks (PPDs). We discuss the implications of theory, meteorite measurements, and astronomical observations for planetary formation and nebular evolution. Paleomagnetic measurements indicate the presence of fields of 0.54 ± 0.21 G at ~1 to 3 astronomical units (AU) from the Sun and ≳0.06 G at 3 to 7 AU until >1.22 and >2.51 million years (Ma) after solar system formation, respectively. These intensities are consistent with those predicted to enable typical astronomically observed protostellar accretion rates of ~10−8M⊙year−1, suggesting that magnetism played a central role in mass transport in PPDs. Paleomagnetic studies also indicate fields <0.006 G and <0.003 G in the inner and outer solar system by 3.94 and 4.89 Ma, respectively, consistent with the nebular gas having dispersed by this time. This is similar to the observed lifetimes of extrasolar protoplanetary disks.

The evolution of rotation in the early history of the Solar System

1984 ◽  
Vol 313 (1524) ◽  
pp. 5-18 ◽  
Keyword(s):  
Dipole Moment ◽  
Angular Momentum ◽  
Solar System ◽  
Giant Planets ◽  
Slow Rotation ◽  
The Sun ◽  
Early Solar System ◽  
Slowing Down ◽  
T Tauri ◽  
History Of

Theories that require the co-genetic formation of the Sun and planets have difficulty in explaining the slow rotation of the Sun. An analysis is made of various mechanisms for slowing down the core of an evolving nebula. Two of these involve a high magnetic dipole moment for the early Sun. The first envisages magnetic linkage to an external plasma but requires a dipole moment 10 6 times that of the present Sun. The other is based on the co-rotation of m atter leaving the Sun during a T Tauri stage, and requires a dipole moment 10 4 times the present value. A mechanical process for transferring angular momentum outward involving dissipation in a solar-nebula disc is incapable of giving what is required. Two processes of star formation in a turbulent cloud are discussed. Both are capable of giving a slowly rotating Sun. Various models for producing planets are examined in relation to the spin they would produce. Planets formed from floccules would be spinning quickly but could evolve in such a way as to give observed spins for giant planets and also satellite families. Accretion models are very sensitive to assumptions, and parameters and can be adjusted to explain almost any observation. Protoplanets formed in elliptical orbits would acquire spin angular momentum through solar tidal action and would evolve to give reasonable spin rates and regular satellite families. The various tilts of their spin axes could be explained by interactions between protoplanets in the early Solar System.

scholarly journals Stellar Gravitational Lens Engineering for Interstellar Communication and Artifact SETI

2021 ◽  
Vol 162 (6) ◽  
pp. 252
Author(s):  
Stephen Kerby ◽  
Jason T. Wright
Keyword(s):  
Gravitational Lens ◽  
The Sun ◽  
Propulsion Systems ◽  
Relay System ◽  
Relay Communications ◽  
Nearby Stars ◽  
Interstellar Communication ◽  
Long Timescales ◽  
Communications System

Abstract Several recent works have proposed a “stellar relay” transmission system in which a spacecraft at the focus of a star’s gravitational lens achieves dramatic boosts in the gain of an outgoing or incoming interstellar transmission. We examine some of the engineering requirements of a stellar relay system, evaluate the long-term sustainability of a gravitational relay, and describe the perturbations and drifts that must be actively countered to maintain a relay-star-target alignment. The major perturbations on a relay-Sun-target alignment are the inwards gravity of the Sun and the reflex motion of the Sun imparted by the planets. These ∼m s−1 yr−1 accelerations can be countered with modern propulsion systems over century-long timescales. This examination is also relevant for telescope designs aiming to use the Sun as a focusing element. We additionally examine prospects for an artifact SETI search to observe stellar relays placed around the Sun by an extraterrestrial intelligence and suggest certain nearby stars that are relatively unperturbed by planetary systems as favorable nodes for a stellar relay communications system.

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