Nazhatulshima Ahmad

Acquirement of the observatory code of Langkawi National Observatory

Observatory code was assigned by The International Astronomical Union (IAU) Minor Planet Center (MPC) for a permanent observatory that intended to do astrometric CCD-observing program of minor planet or comets in solar system. The purpose of acquiring an observatory code is to document specific details about a particular observation site and the types of instruments used within the observatory. In addition, many astronomical centers and stations worldwide will know there is an active observatory at the particular location and international cooperation program in astronomy observation is possible. The Langkawi National Observatory has initiated an observation program to monitor minor planet, specifically those Near Earth Objects (NEOs) that may bring potentially hazardous to the Earth. In order to fulfil the requirement that stated by MPC for undertaking astrometric CCD-observing program, an observatory code was required. The instruments and methods that applied to obtain the observatory code will be discu...

The Pleiades Using Astronomical Spectroscopic Technique within the Range of H‐α Region

The Pleiades is an open star cluster located in the constellation of Taurus, which mainly consists of hot and luminous B‐type stars. Observations were conducted over five‐day period in December 2009 at Langkawi National Observatory, Malaysia by using 20‐inch telescope diameter of Ritchey‐Chretien reflector telescope, together with SBIG Self Guided Spectrograph and SBIG ST‐7 CCD camera. The spectra of seven main members of the cluster, namely Alcyone; Atlas; Celaeno; Electra; Maia; Merope and Taygeta; and of Alcyone B; a smaller component of Alcyone quadruple system, were obtained in the optical range of approximately 6300 A to 7100 A. This range was picked due to the vicinity of Balmer H‐α spectral line at 6562.852 A. Alcyone, Electra and Merope were found to have H‐α emissions possibly caused by the presence of equatorial circumstellar disks or envelopes made up of ejected matter. Electra and Merope in particular exhibited peculiar asymmetric double emission peaks, which could be evidence of one‐armed de...

Evolutionary study of the Be star 28 Tau

We present an evolutionary study of 28 Tau, a Be star, in connection with its rapid rotation. The photometric data during the absence of its envelope in 1921 have been used to determine the effective temperature and luminosity of the star at the main sequence of the HR diagram. From an evolutionary model, we found that the mass and radius of the star are about 3.2 M ⊙ and 3.2 R ⊙ respectively. The equatorial rotation velocity of the star, ν e found to be close to its critical velocity, ν cr where ν e /ν cr ≃ 0.87.