A. Gómez, S. Grenier, S. Udry, M. Haywood, V. Sabas, L. Meillon, F. Royer, Y. Lebreton
{"title":"Kinematics of Disk Stars in the Solar Neighbourhood","authors":"A. Gómez, S. Grenier, S. Udry, M. Haywood, V. Sabas, L. Meillon, F. Royer, Y. Lebreton","doi":"10.1017/S1539299600022310","DOIUrl":null,"url":null,"abstract":"Using Hipparcos parallaxes and proper motions together with radial velocity complementary data (Coravel for late type stars and new ground-based data for early type stars) for several thousand B-F type stars, the velocity ellipsoid has been determined as a function of age. The variations with age of the ratio of the velocity dispersions, of the vertex deviation and the age-velocity dispersion relation (AVR) have been estimated. Our results connrm that mixing is not complete at about 0:8 ? 1 Gyr. The shape of the velocity ellipsoid changes with time, getting rounder from a maximum, thereafter remaining roughly constant; there is no dynamically signiicant evolution of the disk after about 4 ? 5 Gyr. The velocity dispersion in the direction perpendicular to the galactic plane saturates at about 15?17 km s ?1 for thin disk stars. The vertex deviation declines with age and remains near zero after 5 Gyr.","PeriodicalId":422890,"journal":{"name":"Highlights of Astronomy","volume":"29 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"1997-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"7","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Highlights of Astronomy","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1017/S1539299600022310","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 7
Abstract
Using Hipparcos parallaxes and proper motions together with radial velocity complementary data (Coravel for late type stars and new ground-based data for early type stars) for several thousand B-F type stars, the velocity ellipsoid has been determined as a function of age. The variations with age of the ratio of the velocity dispersions, of the vertex deviation and the age-velocity dispersion relation (AVR) have been estimated. Our results connrm that mixing is not complete at about 0:8 ? 1 Gyr. The shape of the velocity ellipsoid changes with time, getting rounder from a maximum, thereafter remaining roughly constant; there is no dynamically signiicant evolution of the disk after about 4 ? 5 Gyr. The velocity dispersion in the direction perpendicular to the galactic plane saturates at about 15?17 km s ?1 for thin disk stars. The vertex deviation declines with age and remains near zero after 5 Gyr.