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AN EAST-ASIAN EXTRA-SOLAR PLANET SEARCH NETWORK
IZUMIURA HIDEYUKI The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2
We are undertaking an extra-solar planet search around G-type giant stars by means of Doppler technique using an iodine absorption cell installed to the high dispersion echelle spectrograph for the 188 cm reflector at Okayama Astrophysical Observatory (Okayama Planet Search Program, OPSP). Having detected the first planet candidate (Sato et al. 2003)the search has been proved very promising. Taking advantage of this success, we are trying to develop OPSP to an international collaborative work. We here report the current status of our efforts for establishing such collaborations, namely, those with Chinese and Korean astronomers. We also propose to establish an East-Asian network to search for extra-solar planets around G-type giant stars with the transit detecting technique as well as the Doppler technique, asking other persons/groups to join us to enjoy the planet search.
Kambe, Eiji,Ando, Hiroyasu,Sato, Bun’ei,Izumiura, Hideyuki,Sekii, Takashi,Paulson, Diane B.,Yanagisawa, Kenshi,Masuda, Seiji,Shibahashi, Hiromoto,Hatzes, Artie P.,MARTI´C, Milena,LEBRUN, Jean-Claude,M Astronomical Society of Japan 2008 Publications of the Astronomical Society of Japan Vol.60 No.1
An improvement of the radial-velocity measurement accuracy is crucial for the detection of tiny stellar oscillationsand exoplanets. Through the analysis of week-long extensive observations of solar-type stars (Procyon in 2000, 2002, and 2006/2007 and τ Cet in 2002 and 2006/2007), we have carefully examined, revised, and finelytuned the widely used multiple Gaussian IP fitting method for the spectrograph, HIDES. By determining a necessaryand sufficient number of free parameters in the model as well as introducing an iterative process in the radial-velocityanalysis, we can reach a precision of below 3ms<SUP>-1</SUP>, which is much smaller than the precision of 6ms<SUP>-1</SUP> officially announced so far for HIDES. We also make our technique refined for the 2002 McDonald Procyon data. Even with our revised method, slow radial velocity variations with an amplitude of about 10ms<SUP>-1</SUP> are left in the Procyon data. We emphasize that it is neither due to particular observing instruments nor radial-velocity analysis, and thus could be due to stellar origin. The analysis presented here makes the foundations of our next scientific analysis of the radial-velocity variations of Procyon, which will be presented in our forthcoming papers.
Detection of planet candidates around K giants. HD 40956, HD 111591, and HD 113996
Jeong, G.,Lee, B.-C.,Han, I.,Omiya, M.,Izumiura, H.,Sato, B.,Harakawa, H.,Kambe, E.,Mkrtichian, D. Springer-Verlag 2018 Astronomy and astrophysics Vol.610 No.-
<P><I>Aims. </I>The purpose of this paper is to detect and investigate the nature of long-term radial velocity (RV) variations of K-type giants and to confirm planetary companions around the stars. </P><P><I>Methods. </I>We have conducted two planet search programs by precise RV measurement using the 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) and the 1.88 m telescope at Okayama Astrophysical Observatory (OAO). The BOAO program searches for planets around 55 early K giants. The OAO program is looking for 190 G-K type giants. </P><P><I>Results. </I>In this paper, we report the detection of long-period RV variations of three K giant stars, HD 40956, HD 111591, and HD 113996. We investigated the cause of the observed RV variations and conclude the substellar companions are most likely the cause of the RV variations. The orbital analyses yield <I>P</I> = 578.6 ± 3.3 d, <I>m</I> sin <I>i</I> = 2.7 ± 0.6 <I>M</I>J, <I>a</I> = 1.4 ± 0.1 AU for HD 40956; <I>P</I> = 1056.4 ± 14.3 d, <I>m</I> sin <I>i</I> = 4.4 ± 0.4 <I>M</I>J, <I>a</I> = 2.5 ± 0.1 AU for HD 111591; <I>P</I> = 610.2 ± 3.8 d, <I>m</I> sin <I>i</I> = 6.3 ± 1.0 <I>M</I>J, <I>a</I> = 1.6 ± 0.1 AU for HD 113996. </P>