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1.
Geopotential harmonics of order 15 and even degree,from changes in orbital eccentricity at resonance
When a satellite orbit decaying slowly under the action of air drag experiences 15th-order resonance with the Earth's gravitational field, so that the ground track repeats after 15 rev, the orbital eccentricity may suffer appreciable changes due to perturbations from the gravitational harmonics of order 15 and even degree (16, 18, 20…). In this paper the changes in eccentricity at resonance for six satellites in near-circular orbits at inclinations between 56 and 90° have been analysed to derive 11 pairs of equations linking the harmonic coefficients of order 15 and (even) degree l, in the usual notation. These equations (together with eight constraint equations) are solved to give:
109 | 109 | |
16 | ?13.7 ± 1.3 | ?18.5 ± 2.7 |
18 | ?42.3 ± 1.8 | ?34.7 ± 3.4 |
20 | 10.5 ± 3.1 | 29.8 ± 5.2 |
22 | ?8.6 ± 3.8 | ?20.2 ± 7.4 |
Feb 1958 to mid 1960 | 1.5 rev/day | |
Mid 1960 to Dec 1967 | 1.2 rev/day | |
Jan 1968 to Mar 1970 | 1.3 rev/day |
l | 109C?l,15 | 109S?l,15 |
15 | ?21.5 ± 0.9 | ?8.4 ± 0.9 |
17 | 4.4 ± 1.6 | 9.0 ± 1.5 |
19 | ?15.6 ± 2.6 | ?14.1 ± 2.7 |
21 | 10.4 ± 3.0 | 7.3 ± 3.5 |
23 | 22.5 ± 2.8 | 1.2 ± 4.4 |
25 | ?0.9 ± 4.7 | ?3.8 ± 5.3 |
27 | ?11.2 ±3.3 | 9.1 ± 3.2 |
29 | ?20.5 ± 5.4 | ?1.2 ± 6.1 |
31 | 17.7 ± 6.6 | ?1.0 ± 7.1 |
l | 109C?l,15 | 109S?l,15 |
15 | ?23.5 ± 0.8 | ?7.7 ± 0.8 |
17 | 6.3 ± 1.5 | 5.6 ± 1.5 |
19 | ?25.1 ± 2.5 | ?7.3 ± 2.3 |
21 | 27.8 ± 3.6 | ?0.7 ± 3.4 |
23 | 17.1 ± 4.1 | 13.9 ± 4.8 |
25 | ?1.1 ± 3.0 | 8.5 ± 4.2 |
27 | 10.0 ± 3.3 | 6.7 ± 2.7 |
29 | ?9.4 ± 3.5 | 0.1 ± 4.7 |
31 | 10.1 ± 5.4 | 3.8 ± 5.6 |
33 | 1.1 ± 5.7 | 3.1 ± 5.8 |
109C? | 109S?l,14 | |
- | - | - |
14 | ?38.5 ±2.9 | ?7.8 ±2.2 |
15 | 4.5 ±1.1 | ?23.8 ±0.3 |
16 | ?22.3 ±3.6 | ?36.0 ±3.8 |
17 | ?15.0 ±2.6 | 16.8 ±1.2 |
18 | ?24.0±4.9 | ?3.2 ±3.7 |
19 | ?1.6 ±2.8 | ?7.6 ±1.0 |
20 | 8.8 ±5.8 | ?15.4 ±4.6 |
21 | 18.2 ±3.6 | ?10.6 ±1.9 |
22 | ?14.5 ±8.1 | 9.9 ±6.4 |
9.
《Experimental Astronomy》2009,23(1):435-461
As a response to ESA call for mission concepts for its Cosmic Vision 2015–2025 plan, we propose a mission called Darwin. Its primary goal is the study of terrestrial extrasolar planets and the search for life on them. In this paper, we describe
different characteristics of the instrument.
相似文献
Charles S. CockellEmail: |
10.
A new calibration to determine the closure temperatures of Fe‐Mg ordering in augite from nakhlites 下载免费PDF全文
M. Alvaro M. C. Domeneghetti A. M. Fioretti F. Cámara L. Marinangeli 《Meteoritics & planetary science》2015,50(3):499-507
Recently it has been shown that the relatively low closure temperature (Tc) of 500 (100)°C calculated for augite from Miller Range nakhlite (MIL 03346,13) using the available geothermometers would correspond to a slow cooling rate inconsistent with the petrologic evidence for an origin from a fast‐cooled lava flow. Moreover, previous annealing experiments combined with HR‐SC‐XRD on an augite crystal from MIL 03346 clearly showed that at 600 °C, the Fe2+‐Mg degree of order remained unchanged, thus suggesting that the actual Tc is close to this temperature. In order to clarify this discrepancy, we undertook an ex situ annealing experimental study at 700, 800, and 900 °C, until the equilibrium in the intracrystalline Fe2+‐Mg exchange is reached, using an augite crystal from Miller Range nakhlite (MIL 03346,13) with a composition of about En36Fs24Wo40. These data allowed us to calculate the following new geothermometer calibration for Martian nakhlites: where The application of this new equation to other Martian nakhlites (NWA 988 and Nakhla) suggests that for augite with composition close to that of MIL 03346, the Tc is up to 170 °C higher with respect to the one calculated using the previous available geothermometer equation, thus suggesting a significantly faster cooling in agreement with petrologic evidence. 相似文献
11.
E. V. Malogolovets Yu. Yu. Balega D. A. Rastegaev K. -H. Hofmann G. Weigelt 《Astrophysical Bulletin》2007,62(2):117-124
Speckle interferometric observations made with the 6 m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences in 2000 revealed the triple nature of the nearby (π Hip = 51.80 ± 1.74 mas) low-mass young (≈ 200 Myr) star GJ 900. The configuration of the triple system allowed it to be dynamically unstable. Differential photometry performed from 2000 through 2004 yielded I- and K-band absolute magnitudes and spectral types for the components to be I A =6.66±0.08, I B =9.15±0.11, I C =10.08±0.26, K A =4.84±0.08, K B =6.76±0.20, K C =7.39±0.31, Sp A ≈K5?K7, Sp B ≈M3?M4, Sp C ≈M5?M6. The “mass-luminosity” relation is used to estimate the individual masses of the components: M A ≈0.64M ⊙, M B ≈0.21M ⊙, M C ≈0.13M ⊙. From the observations of the components’ relative motion in the period 2000–2006, we conclude that GJ 900 is a hierarchical triple star with the possible orbital periods PA-BC≈80 yrs and PBC≈20 yrs. An analysis of the 2MASS images of the region around GJ 900 leads us to suggest that the system can include other very-low-mass components. 相似文献
12.
T. Appourchaux P. Liewer M. Watt D. Alexander V. Andretta F. Auchère P. D’Arrigo J. Ayon T. Corbard S. Fineschi W. Finsterle L. Floyd G. Garbe L. Gizon D. Hassler L. Harra A. Kosovichev J. Leibacher M. Leipold N. Murphy M. Maksimovic V. Martinez-Pillet B. S. A. Matthews R. Mewaldt D. Moses J. Newmark S. Régnier W. Schmutz D. Socker D. Spadaro M. Stuttard C. Trosseille R. Ulrich M. Velli A. Vourlidas C. R. Wimmer-Schweingruber T. Zurbuchen 《Experimental Astronomy》2009,23(3):1079-1117
The POLAR Investigation of the Sun (POLARIS) mission uses a combination of a gravity assist and solar sail propulsion to place
a spacecraft in a 0.48 AU circular orbit around the Sun with an inclination of 75° with respect to solar equator. This challenging
orbit is made possible by the challenging development of solar sail propulsion. This first extended view of the high-latitude
regions of the Sun will enable crucial observations not possible from the ecliptic viewpoint or from Solar Orbiter. While
Solar Orbiter would give the first glimpse of the high latitude magnetic field and flows to probe the solar dynamo, it does
not have sufficient viewing of the polar regions to achieve POLARIS’s primary objective: determining the relation between
the magnetism and dynamics of the Sun’s polar regions and the solar cycle.
相似文献
T. AppourchauxEmail: |
13.
P. P. Hallan Sanjay Jain K. B. Bhatnagar 《Celestial Mechanics and Dynamical Astronomy》2000,77(3):157-184
The non-linear stability of L
4 in the restricted three-body problem has been studied when the bigger primary is a triaxial rigid body with its equatorial
plane coincident with the plane of motion. It is found that L
4 is stable in the range of linear stability except for three mass ratios:
where A1, A2 depend upon the lengths of the semi axes of the triaxial rigid body.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Douglas C. Heggie 《Celestial Mechanics and Dynamical Astronomy》1976,14(1):69-71
It has been shown (Heggie, 1974) that the equations of motion for the three-body problem may be cast into a form which is regular for collisions betweenany pair of bodies. The method proceeds by two stages, namely
The present contribution gives a different treatment of the first of these stages, and relates the redundant variables to those introduced by Broucke and Lass (1973). 相似文献
(i) | the introduction of redundant variables |
(ii) | the application of the KS-transformation. |
15.
K. B. Bhatnagar Usha Gupta Rashmi Bhardwaj 《Celestial Mechanics and Dynamical Astronomy》1994,59(4):345-374
The non-linear stability of the libration pointL
4 in the restricted problem has been studied when there are perturbations in the potentials between the bodies. It is seen that the pointL
4 is stable for all mass ratios in the range of linear stability except for three mass ratios depending upon the perturbing functions. The theory is applied to the following four cases:
相似文献
(i) | There are no perturbations in the potentials (classical problem). |
(ii) | Only the bigger primary is an oblate spheroid whose axis of symmetry is perpendicular to the plane of relative motion (circular) of the primaries. |
(iii) | Both the primaries are oblate spheroids whose axes of symmetry are perpendicular to the plane of relative motion (circular) of the primaries. |
(iv) | The primaries are spherical in shape and the bigger is a source of radiation. |
16.
M. Ollivier O. Absil F. Allard J.-P. Berger P. Bordé F. Cassaing B. Chazelas A. Chelli O. Chesneau V. Coudé du Foresto D. Defrère P. Duchon P. Gabor J. Gay E. Herwats S. Jacquinod P. Kern P. Kervella J.-M. Le Duigou A. Léger B. Lopez F. Malbet D. Mourard D. Pelat G. Perrin Y. Rabbia D. Rouan J.-M. Reiss G. Rousset F. Selsis P. Stee J. Surdej 《Experimental Astronomy》2009,23(1):403-434
PEGASE is a mission dedicated to the exploration of the environment (including habitable zone) of young and solar-type stars
(particularly those in the DARWIN catalogue) and the observation of low mass companions around nearby stars. It is a space
interferometer project composed of three free flying spacecraft, respectively featuring two 40 cm siderostats and a beam combiner
working in the visible and near infrared. It has been proposed to ESA as an answer to the first “Cosmic Vision” call for proposals,
as an M mission. The concept also enables full-scale demonstration of space nulling interferometry operation for DARWIN.
相似文献
M. OllivierEmail: |
17.
In this paper we present new and exact analytical and computational developments of Güttler's formulae for composite grains, thereafter applied for the two models:
Literal and analytical expressions have been established for the Riccati-Bessel of the complex functions
n
,
n
, and
n
and their derivatives. The problem is treated in its general form without any restriction and the computer programme is now ready for request. 相似文献
(1) | Graphite core-ice mantle. |
(2) | Silicate core-ice mantle. |
18.
The Space Infrared telescope for Cosmology and Astrophysics (SPICA) is planned to be the next space astronomy mission observing
in the infrared. The mission is planned to be launched in 2017 and will feature a 3.5 m telescope cooled to <5 K through the
use of mechanical coolers. These coolers will also cool the focal plane instruments thus avoiding the use of consumables and
giving the mission a long lifetime. SPICA’s large, cold aperture will provide a two order of magnitude sensitivity advantage
over current far infrared facilities (>30 microns wavelength). We describe the scientific advances that will be made possible
by this large increase in sensitivity and give details of the mission, spacecraft and focal plane conceptual design.
相似文献
Bruce SwinyardEmail: |
19.
The purpose of this paper is to find correlation between OI 6300 Å line intensity with solar and ionospheric parameters. A critical study have been made and the following important results are obtained:
相似文献
(i) | Solar flare index plays more important role for the emissions of 6300 Å line than other solar parameters. |
(ii) | Intensity of 6300 Å line increases linearly with the increase of solar flare index. |
(iii) | Virtual height plays more important role than critical frequency for the emission of 6300 Å line-intensity. |
(iv) | Possible explanation of this type of variation is also presented. |
20.
We analyze the relationship between the coronal hole (CH) area/position and physical characteristics of the associated corotating
high-speed stream (HSS) in the solar wind at 1 AU. For the analysis we utilize the data in the period DOY 25 – 125 of 2005,
characterized by a very low coronal mass ejection (CME) activity. Distinct correlations between the daily averaged CH parameters
and the solar wind characteristics are found, which allows us to forecast the solar wind velocity v, proton temperature T, proton density n, and magnetic field strength B, several days in advance in periods of low CME activity. The forecast is based on monitoring fractional areas A, covered by CHs in the meridional slices embracing the central meridian distance ranges [−40°,−20°], [−10°,10°], and [20°,40°].
On average, the peaks in the daily values of n, B, T, and v appear delayed by 1, 2, 3, and 4 days, respectively, after the area A attains its maximum in the central-meridian slice. The peak values of the solar wind parameters are correlated to the peak
values of A, which provides also forecasting of the peak values of n, B, T, and v. The most accurate prediction can be obtained for the solar wind velocity, for which the average relative difference between
the calculated and the observed peak values amounts to
%. The forecast reliability is somewhat lower in the case of T, B, and n (
, 30, and 40%, respectively). The space weather implications are discussed, including the perspectives for advancing the real-time
calculation of the Sun – Earth transit times of coronal mass ejections and interplanetary shocks, by including more realistic
real-time estimates of the solar wind characteristics. 相似文献
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