Journal of Science and Applicative Technology – Institut Teknologi Sumatera 14 FITTING ISOCHRONE OF HYADES STAR CLUSTER BY BUILDING COLOUR MAGNITUDE DIAGRAM (CMD) Annisa Novia Indra Putri 1 1 Institut Teknologi Sumatera, Lampung Selatan, Lampung Abstract: Sky survey of Star cluster from many projects have many informations about our Galaxy, Milky Way. Hyades star cluster is the nearest open cluster and one of the best-studied star cluster. Its location about 153 light-years away from the Solar System consist of roughly spherical group of hundreds of stars. Earlier information from this cluster can be used to constraint other paramaters such as structuer, composition, dynamic formation, and evolution of Galaxy. Aim this research is fitting model of simple Colour Magnitude Diagram (CMD) with isochrone from Hyades data using monte caro method including binary star fraction effect and fotometry uncertainty. Basic parameter Hyades data is taken from WEBDA while isochrone Hyades data is taken from Padova site. The result from this research is limiting magnitude instrument observing Hyades around 16 mag. There are some points of Hyades data forming new main sequence under real main sequence which fit with model due to closer distance of Hyades star cluster from the Sun. Keywords: Open cluster, Hyades, Color Magnitude Diagram, Isochrone 1. Introduction Stars are formed from big cloud called nebula and as group called cluster. Star cluster is assumed as Simple Stellar Population (SSP). SSP is an object formed at the same time which has same chemical composition, distance, and reddening. Theoretically, SSP is called isochrone. Isochrone from a cluster has a same age but different mass. Star mass correlate with magnitude of star, bigger mass of star so the star will be brighter. Hyades star cluster is one of kind open cluster in the Universe and the nearest open cluster from the Sun. Hyades is located at Taurus constellation consisting of a roughly spherical group of hundred of stars sharing the same age, distance, chemical characteristics, and motion through the space. In this research purpose to do modelling simple Colour Magnitude Diagram (CMD) from open cluster of Hyades then fitting to isochrone Hyades data using monte carlo method. 2. Data and Research Method 2.1 Data Building Color Magnitude Diagram (CMD) need some initial parameters such as isochrone, Initial Mass Function (IMF), reddening, age interval, and metalicity. Initial basic parameter Hyades is taken from WEBDA [1] shown at Table 1. While isochrone of Hyades data use isochrone information at Padova site [2] based on some publications [3,4,5]. Parameter Value RA (J2000) 04 h 26 m 54 s Declination (J2000) +15 o 52’ 00” Galaxy Longitude 180. o 064 Galaxy Latitude -22, o 343 Distance (pc) 45 Reddening (mag) 0,01 Distance Modulus (mag) 3,30 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Journal of Science and Application Technology (JSAT - Institut Teknologi Sumatera)