XVI. On the direction and velocity of the motion of the sun, and solar system

1805 ◽  
Vol 95 ◽  
pp. 233-256 ◽  
Keyword(s):  
Solar System ◽  
Relative Position ◽  
The Sun ◽  
Proper Motions ◽  
Double Stars ◽  
Solar Motion ◽  
High Degree

Our attention has lately been directed again to the construc­tion of the heavens, on which I have already delivered several detached papers. The changes which have taken place in the relative position of double stars, have ascertained motions in many of them, which are probably of the same nature with those that have hitherto been called proper motions. It is well known that many of the principal stars have been found to have changed their situation, and we have lately had a most valuable acquisition in Dr. Maskelyne's Table of proper motions of six and thirty of them. If this Table affords us a proof of the motion of the stars of the first brightness, such as are probably in our immediate neighbourhood, the changes of the position of minute double stars that I have ascertained, many of which can only be seen by the best telescopes, likewise prove that motions are equally carried on in the remotest parts of space which hitherto we have been able to penetrate. The proper motions of the stars have long engaged the attention of astronomers, and in the year 1783, I deduced from them, with a high degree of probability, a motion of the sun and solar system towards λ Herculis. The reasons which were then pointed out for introducing a solar motion, will now be much strengthened by additional considerations; and the above mentioned Table of well ascertained proper motions will also enable us to enter rigorously into the necessary calculations for ascertaining its direction, and discovering its velocity. When these points are established, we shall be prepared to draw some consequences from them that will account for many phenomena which otherwise cannot be explained.

scholarly journals On the direction and velocity of the motion of the sun, and solar system

1832 ◽  
Vol 1 ◽  
pp. 197-199
Keyword(s):  
Solar System ◽  
The Other ◽  
The Sun ◽  
Proper Motions ◽  
Future Opportunity ◽  
Original Intention ◽  
Solar Motion ◽  
Rotatory Motion

Although, in the title to this paper, Dr. Herschel mentions both the direction and velocity of the solar system, it is his intention, he says, to limit his inquiries, at present, to the first of these subjects, and to discuss the other at some future opportunity. He is induced to enter into this inquiry, because a solar motion, if established, seems to contradict the original intention for which it was introduced; namely, to take away many of the proper motions of stars, by investing the sun with a contrary one. But as the solar motion will reveal a greater number of concealed real motions than need be admitted if the sun were at rest, the necessity of admitting its motion ought to be well established. From the motion of the secondary planets round the primary ones, and of these round the sun, the solar motion must be allowed to be a very possible event; and the rotatory motion of the sun, from which a displacing of the solar centre has been inferred, also indicates a motion of translation in space; for it does not appear probable that any mechanical impression should produce the former without occasioning the latter.

scholarly journals Proxima’s orbit around α Centauri

2017 ◽  
Vol 598 ◽  
pp. L7 ◽  
Author(s):  
P. Kervella ◽  
F. Thévenin ◽  
C. Lovis
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Orbital Period ◽  
Triple System ◽  
Orbital Motion ◽  
The Sun ◽  
Proper Motions ◽  
Velocity Measurements ◽  
Degree Of Confidence ◽  
High Degree

Proxima and α Centauri AB have almost identical distances and proper motions with respect to the Sun. Although the probability of such similar parameters is, in principle, very low, the question as to whether they actually form a single gravitationally bound triple system has been open since the discovery of Proxima one century ago. Owing to HARPS high-precision absolute radial velocity measurements and the recent revision of the parameters of the α Cen pair, we show that Proxima and α Cen are gravitationally bound with a high degree of confidence. The orbital period of Proxima is ≈ 550 000 yr. With an eccentricity of 0.50+0.08-0.09, Proxima comes within 4.3+1.1-0.9 kau of α Cen at periastron, and is currently close to apastron (13.0+0.3-0.1 kau). This orbital motion may have influenced the formation or evolution of the recently discovered planet orbiting Proxima, as well as circumbinary planet formation around α Cen.

scholarly journals Planets in Double Stars: The ϒ Cephei System

2004 ◽  
Vol 191 ◽  
pp. 222-226 ◽  
Author(s):  
R. Dvorak ◽  
E. Pilat-Lohinger ◽  
E. Bois ◽  
B. Funk ◽  
F. Freistetter ◽  
...  
Keyword(s):  
Solar System ◽  
The Sun ◽  
Stable Orbit ◽  
Orbital Parameters ◽  
Double Stars ◽  
The Stability

AbstractUp to now we have evidence for some 15 planets moving in double stars. They are all of the so-called S-type, which means that they are orbiting one of the primaries. Only two of the binaries have separations in the order of the distances where the planets in our Solar system orbit the Sun, namely Gliese 86 and ϒ Cep. In this study we investigate the stability of the recently discovered planet in ϒ Cep with respect to the orbital parameters of the binary and of the planet. Additionally we check the region inside and outside the planet’s orbit (a = 2.1 AU). Even when the mass of an additional planet in 1 AU would be in the order of that of Jupiter, the discovered planet would be in a stable orbit.

XV. Account of the changes that have happened, during the last twenty-five years, in the relative situation of double-stars; with an investigation of the cause to which they are owing

1803 ◽  
Vol 93 ◽  
pp. 339-382 ◽  
Keyword(s):  
Solar System ◽  
The Other ◽  
The Sun ◽  
Double Stars ◽  
Celestial Bodies ◽  
Planets And Satellites ◽  
The Subject ◽  
Elliptical Orbits ◽  
Asteroids And Comets

In the Remarks on the Construction of the Heavens, contained in my last Paper on this subject, I have divided the various objects which astronomy has hitherto brought to our view, into twelve classes. The first comprehends insulated stars. As the solar system presents us with all the particulars that may be known, respecting the arrangement of the various su­bordinate celestial bodies that are under the influence of stars which I have called insulated, such as planets and satellites, asteroids and comets, I shall here say but little on that subject. It will, however, not be amiss to remark, that the late addition of two new celestial bodies, has undoubtedly enlarged our know­ledge of the construction of the system of insulated stars. Whatever may be the nature of these two new bodies, we know that they move in regular elliptical orbits round the sun. It is not in the least material whether we call them asteroids, as I have proposed; or planetoids, as an eminent astronomer, in a letter to me, suggested; or whether we admit them at once into the class of our old seven large planets. In the latter case, however, we must recollect, that if we would speak with precision, they should be called very small, and exzodiacal; for, the great inclination of the orbit of one of them to the ecliptic, amounting to 35 degrees, is certainly remarkable. That of the other is also considerable; its latitude, the last time I saw it, being more than 15 degrees north. These circumstances, added to their smallness, show that there exists a greater variety of arrange­ment and size among the bodies which our sun holds in subor­dination, than we had formerly been acquainted with, and extend our knowledge of the construction of the solar, or insulated sidereal system. It will not be required that I should add any thing farther on the subject of this first article of my clas­sification; I may therefore immediately go to the second, which treats of binary sidereal systems, or real double stars.

scholarly journals Astrometry with the Large Space Telescope

1974 ◽  
Vol 61 ◽  
pp. 283-292
Author(s):  
W. F. van Altena ◽  
O. G. Franz ◽  
L. W. Fredrick
Keyword(s):  
Solar System ◽  
Star Clusters ◽  
Proper Motions ◽  
High Quality ◽  
Large Space ◽  
Space Telescope ◽  
Double Stars ◽  
Detailed Survey

The Large Space Telescope (LST), planned to be launched in 1980, will give an opportunity for astrometric observations of high quality to be secured.A detailed survey is presented of the potentialities of the LST for studies of proper motions, parallaxes, star clusters, double stars, perturbed motion stars, occultations, fundamental astrometry and solar system observations.The proposed characteristics and design capabilities of the LST are tabulated.

scholarly journals On the proper motion of the solar system

1851 ◽  
Vol 5 ◽  
pp. 669-672
Keyword(s):  
Solar System ◽  
Proper Motion ◽  
A Priori ◽  
Point Of View ◽  
The Sun ◽  
Proper Motions ◽  
Fixed Line ◽  
St Helena ◽  
William Herschel ◽  
Right Ascension

The object of this paper is to communicate the results of a calculation for determining the direction of the proper motion of the solar system from the apparent proper motions of stars in the southern hemisphere, deduced mostly from a comparison of the observations made by Lacaille at the Cape, about the middle of the last century, with the recent observations of Mr. Johnson and the late Professor Henderson at St. Helena and the Cape respectively. After adverting to the papers of Sir William Herschel in the Philo­sophical Transactions for 1783 and 1805, and some other investi­gations of the same subject, the author remarks that up to a recent period astronomers seem generally to have entertained the opinion that our knowledge of the proper motions of the stars is not sufficiently advanced to enable us to pronounce positively either on the fact or the direction of the motion of our own system. This opinion was grounded on the discrepancies which present them­selves when it is attempted to explain the observed displacements of individual stars by referring them to the motion of the sun in an opposite direction; it being always found that whatever direction is assigned to the sun’s motion, there are many stars whose proper motions cannot thereby be accounted for. But if the sun be in motion it is very improbable that any star is absolutely at rest; hence the proper motions deduced from a comparison of catalogues must be regarded as the effect partly of the true proper motions of the stars, and partly of the apparent systematic or parallactic mo­tion caused by the displacement of the point of view; and as we have no reason for supposing the true proper motion of a star to be more probable in one direction than in another, it may be expected, à priori , that the observed directions will form angles of all different values with the direction of the sun’s motion, or any other fixed line. The observed discrepancies are therefore not incompatible with a general drifting of the stars towards a particular region of the heavens; but in order to deduce the direction of the systematic motion, it becomes necessary to take account of a very considerable number of proper motions, and to represent them by equations, involving the unknown quantities required for determining the direction of the sun’s motion, and to solve the equations so as to obtain the most probable values of those quantities. The first person who investigated the subject under this point of view was Professor Argelander of Bonn, in a paper published in the Petersburg Me­moirs for 1837. From the proper motions of 390 stars deduced from a comparison of Bessel’s catalogue of Bradley’s observations with his own catalogue of stars observed at Abo, Argelander found the direction of the sun’s motion, for 1792·5, to be towards the point of the sphere whose right ascension is 259° 47'·6 and declination + 32° 29'·5. Lundahl, subsequently, from a comparison of the places of 147 stars in the catalogues of Bessel and Pond, and not included among those considered by Argelander, found the co-ordinates of the point to be AR=252° 24'·4, Dec.+ 14° 26'·1; and Otto Struve, still more recently, from the comparison of about 400 of Bradley’s stars with the positions determined at the Dorpat Observatory, ob­tained the result AR=261° 23'·1, Dec. + 37° 35'·7. The mean of those results taken with respect to their probable errors, was found by O. Struve to be AR=259° 9'·4, Dec.+ 34° 36'·5.

scholarly journals Comparison Of The Effect Of Various Solar System Ephemerides On Equator And Equinox Solutions From Six-inch Transit Circle Observations Of The Sun

1988 ◽  
Vol 133 ◽  
pp. 501-504
Author(s):  
Zhen-Guo Yao ◽  
Clayton Smith
Keyword(s):  
Solar System ◽  
Zero Point ◽  
The Sun ◽  
Proper Motions ◽  
Orbital Parameters ◽  
The Mean ◽  
The Right ◽  
Right Ascension

Using observations of the sun made with the Washington six-inch transit circle from 1911 to 1971, equator and equinox corrections based on Newcomb's, DE102, and DE200 ephemerides are given for each of six catalogs of results of observations made during that period. Each of these catalogs was observed and discussed fundamentally, that is, in such a way as to decouple the system of the catalog positions from dependence on previously given systems of catalog positions and proper motions.Variations of the solutions for the equator and equinox corrections and of earth orbital parameters including corrections to the ephemeris mean longitude of the sun, the mean obliquity of the ecliptic, the mean longitude of perihelion, and the mean eccentricity of the earth's orbit are discussed for solutions based on the independent catalog systems and on the catalog systems referred to the FK4 and to an improved FK4 in which an epoch dependent correction to the right ascension zero point has been applied.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

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