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 Kinematical Structure of the Local Interstellar Medium

1997 ◽  
Vol 166 ◽  
pp. 195-198
Author(s):  
R. Génova ◽  
J. E. Beckman ◽  
J. Rodríguez Álamo
Keyword(s):  
Interstellar Medium ◽  
Velocity Vector ◽  
Galactic Center ◽  
Galactic Plane ◽  
The Sun ◽  
Local Interstellar Medium

AbstractObservations of interstellar Na I in the spectra of 93 stars within 315 pc from the Sun show that it lies in a tunnel of gas moving away from Scorpio-Centaurus and is surrounded by gas moving toward the Galactic center.Gas approaches the Sun from Scorpio-Centaurus expanding from (r, l, b)=(160 pc, 313°7, +28°2) with LSR velocity 15.3 km s−1. The radius of this shell is 153 pc.We identify these clouds:D: velocity vector (υd, ld, bd)=(+7.2 km s−1, 305°1, −13°5), above and below the Galactic plane (GP) in the range of Galactic longitudes 357°–55°.C: velocity vector (υc, lc, bc)=(+11.5 km s−1, 349°0, −35°2), above and below the GP in the range 30°≤l≤110°.M: velocity vector (υm, lm, bm)=(+21.9 km s−1, 34°2, +1°5), above and below the GP in the range 100°≤l≤130°.P: velocity vector (υp, lp, bp)=(+13.8 km s−1, 244°9, +5°4), above and below the GP from l~120° to the limit of our data at l~210°.E: velocity vector (υe, le, be)=(+16.8 km s−1, 208°4, +6°2) in the range 160°≤l≤185° and −10°≤b≤–35°.A: velocity vector (υa, la, ba)=(+12.9 km s−1, 73°6, −5°6) towards the Galactic anti-center, below the GP.I: velocity vector (υi, li, bi)=(+37.7 km s−1, 132°8, −64°3) towards the Galactic anti-center, above the GP.

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 Local Bubble and Beyond: Summary

1997 ◽  
Vol 166 ◽  
pp. 563-580 ◽  
Author(s):  
Christopher F. McKee
Keyword(s):  
Interstellar Medium ◽  
Galactic Plane ◽  
Low Density ◽  
The Sun ◽  
Local Bubble ◽  
Current State ◽  
The Galaxy ◽  
Theoretical Discovery ◽  
Gaseous Halo

Lyman Spitzer, Jr, the founder of modern studies of the interstellar medium (ISM), passed away March 31, 1997. This conference occurred shortly thereafter and is dedicated to his memory. While many of his contributions underlie the work that was discussed at this meeting, one paper stands out in particular: his theoretical “discovery” of the hot gaseous halo of the Galaxy based on the need to confine the clouds of H I observed above the Galactic plane (Spitzer 1956). We now know that much of the ISM within about 100 pc of the Sun is largely filled by very low density gas, which is generally inferred to be hot, and as a result this region is termed the Local Bubble (Cox and Reynolds 1987). This conference was convened to establish the current state of our knowledge of the Local Bubble, both observational and theoretical, and its relation to the rest of the ISM. Because it is nearby, the Local Bubble is a laboratory for interstellar astrophysics, making the dedication to Spitzer’s memory particularly appropriate.

scholarly journals On the galactocentric orbits of nearby stars

1999 ◽  
pp. 45-52 ◽  
Author(s):  
S. Ninkovic ◽  
N. Popovic ◽  
V. Zivkov
Keyword(s):  
Galactic Plane ◽  
Initial Conditions ◽  
Meridional Plane ◽  
Galactic Rotation ◽  
The Sun ◽  
Axially Symmetric ◽  
Circular Velocity ◽  
Phase Coordinates ◽  
Solar Motion ◽  
Nearby Stars

Using the data from the Gliese-Jahreiss Catalogue and a particular form of the galactic potential the authors construct galactocentric orbits for nearby stars. The potential used in our paper is stationary and axially symmetric with three contributors - bulge, disc and dark corona. In the calculating of the galactocentric phase coordinates the distance of the Sun to the galactic plane is neglected, the asymmetric drift is not, whereas the components of the solar motion are varied; the distance of the Sun to the axis of galactic rotation and the corresponding value of the circular velocity are assumed according to the model used in the paper. The obtained orbits (projection on meridional plane) in a vast majority are box-like, or more precisely trapezium-like. The effect of the assumed solar motion is discussed and comparisons with results obtained by applying different potentials and initial conditions are made.

scholarly journals Statistical Properties of Extrasolar Planets

2004 ◽  
Vol 202 ◽  
pp. 3-11 ◽  
Author(s):  
R. Paul Butler ◽  
Geoffrey W. Marcy ◽  
Debra A. Fischer ◽  
Steven S. Vogt ◽  
C. G. Tinney ◽  
...  
Keyword(s):  
Detection Limit ◽  
Solar System ◽  
Mass Distribution ◽  
Binary Stars ◽  
Extrasolar Planets ◽  
Statistical Properties ◽  
The Sun ◽  
Eccentric Orbits ◽  
Nearby Stars ◽  
Solar Type

The emerging statistical properties from the first 50 extrasolar planets are startlingly different from the picture that was imagined prior to 1995. About 0.75% of nearby solar type stars harbor jovian planets in 3 to 5 day circular orbits. Another ∽7% of stars have jupiter–mass companions orbiting in eccentric orbits within 3.5 AU. The mass distribution of substellar companions rises abruptly near 5 MJup and continues increasing down to the detection limit near 1 MJup-Orbital eccentricities correlate positively with semimajor axes, even for planets beyond the tidal circularization zone within 0.1 AU, distinguishing planets from binary stars. The planet bearing stars are metal–rich relative to both nearby stars and to the Sun. Analogs of Solar System planets have not been detected to date as they require precision of 3 m s−1 maintained for more than a decade.

scholarly journals Possible Interaction of Interstellar Particles With the Solar and Terrestrial Environment

1971 ◽  
Vol 13 ◽  
pp. 375-377
Author(s):  
J. Mayo Greenberg
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Interstellar Medium ◽  
Solar Magnetic Field ◽  
Repulsive Force ◽  
The Sun ◽  
Terrestrial Environment ◽  
Particle Penetration

The possibility for detection of interstellar particles in the Earth’s environment is considered on the basis of the passage of the solar system through the interstellar medium. Among the forces which inhibit interstellar particle penetration, the deflection by the solar magnetic field and the repulsive force due to the radiation from the Sun are by far the most important.

scholarly journals The Intrinsic Properties of the Local Interstellar Medium

1997 ◽  
Vol 166 ◽  
pp. 29-32 ◽  
Author(s):  
Olivia Puyoo ◽  
Lotfi Ben Jaffel
Keyword(s):  
Solar System ◽  
Interstellar Medium ◽  
Interstellar Cloud ◽  
Actual State ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Intrinsic Properties ◽  
Hydrogen Density ◽  
Self Consistent ◽  
Local Cloud

AbstractWe propose a new method to constrain the actual state of the interstellar cloud that surrounds the solar system. Using Voyager UVS Lyman-α sky maps and the powerful principle of invariance, we derive the H distribution all along the spacecraft path. Provided current models of the heliopause interface between the solar and the interstellar winds, we extrapolate this distribution to farther distances from the Sun and infer in a self consistent way key parameters of the local cloud. Our findings are a high interstellar hydrogen density of ~ 0.24 cm−3 and a weak ionization .

Decades-Long Changes of the Interstellar Wind Through Our Solar System

Science ◽  
2013 ◽  
Vol 341 (6150) ◽  
pp. 1080-1082 ◽  
Author(s):  
P. C. Frisch ◽  
M. Bzowski ◽  
G. Livadiotis ◽  
D. J. McComas ◽  
E. Moebius ◽  
...  
Keyword(s):  
Solar System ◽  
Interstellar Medium ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Data Types ◽  
Explorer Mission ◽  
Interstellar Material ◽  
Ecliptic Longitude

The journey of the Sun through the dynamically active local interstellar medium creates an evolving heliosphere environment. This motion drives a wind of interstellar material through the heliosphere that has been measured with Earth-orbiting and interplanetary spacecraft for 40 years. Recent results obtained by NASA's Interstellar Boundary Explorer mission during 2009–2010 suggest that neutral interstellar atoms flow into the solar system from a different direction than found previously. These prior measurements represent data collected from Ulysses and other spacecraft during 1992–2002 and a variety of older measurements acquired during 1972–1978. Consideration of all data types and their published results and uncertainties, over the three epochs of observations, indicates that the trend for the interstellar flow ecliptic longitude to increase linearly with time is statistically significant.

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 Bayesian constraints on the origin and geology of exo-planetary material using a population of externally polluted white dwarfs

2021 ◽  
Author(s):  
John H D Harrison ◽  
Amy Bonsor ◽  
Mihkel Kama ◽  
Andrew M Buchan ◽  
Simon Blouin ◽  
...  
Keyword(s):  
Solar System ◽  
White Dwarf ◽  
Bayesian Model ◽  
Total Mass ◽  
White Dwarfs ◽  
Bulk Composition ◽  
Planetary Systems ◽  
The Moon ◽  
Planetary Bodies ◽  
Nearby Stars

Abstract White dwarfs that have accreted planetary bodies are a powerful probe of the bulk composition of exoplanetary material. In this paper, we present a Bayesian model to explain the abundances observed in the atmospheres of 202 DZ white dwarfs by considering the heating, geochemical differentiation, and collisional processes experienced by the planetary bodies accreted, as well as gravitational sinking. The majority (>60%) of systems are consistent with the accretion of primitive material. We attribute the small spread in refractory abundances observed to a similar spread in the initial planet-forming material, as seen in the compositions of nearby stars. A range in Na abundances in the pollutant material is attributed to a range in formation temperatures from below 1,000 K to higher than 1,400 K, suggesting that pollutant material arrives in white dwarf atmospheres from a variety of radial locations. We also find that Solar System-like differentiation is common place in exo-planetary systems. Extreme siderophile (Fe, Ni or Cr) abundances in 8 systems require the accretion of a core-rich fragment of a larger differentiated body to at least a 3σ significance, whilst one system shows evidence that it accreted a crust-rich fragment. In systems where the abundances suggest that accretion has finished (13/202), the total mass accreted can be calculated. The 13 systems are estimated to have accreted masses ranging from the mass of the Moon to half that of Vesta. Our analysis suggests that accretion continues for 11Myrs on average.

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