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Binary Orbit Determination by Using a Variety of Observational Data

Ren, S. L.

The binary orbit determination is a basic research area in astronomy, its main products are the kinematical parameters of binary, which contain the kinematical parameters of the mass center and the orbital parameters. These parameters are the necessary constituents of the astronomical reference frame with high precision and high density, and at th…

The Evolution of Star Formation in Early-type Galaxies

Zheng, X. Z.; Wang, F.

How the star formation activity in early-type galaxies (ETGs) evolves over cosmic time provides observational constraints on the picture of the formation and evolution of ETGs. Using HST/ACS (Hubble Space Telescope/Advanced Camera for Surveys) imaging data from the GEMS (Galaxy Evolution from Morphology and SEDs) survey and multi-band data in the …

Positioning Reduction of Deep Space Probes Based on VLBI Tracking

Qiao, S. B.

In the background of the Chinese Lunar Exploration Project and the Yinghuo Project, through theoretical analysis, algorithm study, software development, data simulation, real data processing and so on, the positioning reductions of the European lunar satellite Smart-1 and Mars Express (MEX) satellite, as well as the Chinese Chang'e-1 (CE-1) and Ch…

The Speed Distributions of CMEs after the Projection Correction

Li, K. J.; Gao, P. X.

Observations of coronal mass ejections (CMEs) with coronagraphs are subject to the projection effect, which results in statistical errors in many properties of CMEs, such as the speed. In this paper, using the method based on the cone model to correct the speeds of CMEs due to the projection effect, we study the speed distribution of CMEs before a…

A Kinematical Study for the Galaxy Based on the Revised Hipparcos Astrometric Data

Zhang, H.; Shen, M.

On the basis of the revised Hipparcos data recently released, the zero-point of the PL relation for classical cepheids was reexamined. Fitting proper motion and radial velocity data via an axis symmetric model, Oort constants and circular rotation velocity of the LSR were calculated to obtain Galactocentric distance of the sun, R0 = 8.0±0.8 kpc. F…

Scale height of the thin galactic disk in solar neighborhood

Zhu, Z.; Kong, D. L.

Thanks to astrometric data of unprecedented accuracy from Hipparcos Catalogue

(ESA 1997), it becomes possible to investigate, by directly counting stars, the scale height of the thin Galactic disk in solar neighborhood defined by the perpendicular distribution of stellar populations. In order to trace out the evolution of scale height, which …

A method of determining binary orbits by incorporating long-term observational data

Fu, Y. N.; Ren, S. L.

Early ground based observations accumulated a large amount of long-term data about binary stellar systems. Compared with the data obtained by various present-day techniques, the early data have much lower precision. However, the span of the longer time interval makes these data still irreplaceable in certain astronomical researches. The present wo…

Precessional correction and the proper-motion systems of FK5 and Hipparcos

Zhu, Z.

Comparing proper motions of the FK5 and Hipparcos, several authors declared that the two proper-motion systems are inconsistent with the value of the precessional correction obtained from VLBI and LLR observations. Based on the proper-motion data from the PPM and ACRS catalogues which are constructed on the FK5 system, the discrepant values of the…

Near infrared photometry for 20 Hipparcos carbon stars

Chen, P. S.; Yan, X. H.; Wang, X. H.

The near infrared photometry in the JHK bands is made for 20 Hipparcos carbon stars. From the results of the near infrared photometry, the bolometric corrections in the K band, the apparent bolometric magnitudes and the effective temperatures can be estimated. Combined with the trigonometric parallaxes observed with the Hipparcos satellite, the ab…

Fuzzy classification of coronal mass ejection properties

Tang, Y. H.; Han, Z. Z.

Fuzzy set theory is applied to a quantitative study of coronal mass ejection properties for importance category. The membership function can be determined according to statistical results and the correlation between CME morphology properties and characteristic factors. CME importance category has been obtained by data reduction. A useful software …