Hakim L. Malasan

The central star of planetary nebula LT-5 - A triple system

IN Com, the central star of the planetary nebula LT-5, is concluded to be a triple system as a result of photometric and spectroscopic examination. Data from UBV photometric and high-dispersion spectroscopic studies conducted between 1984 and 1989 are analyzed by means of a light curve and radial velocity studies. The radial velocity studies show that a single-lined binary with a period of 1.7545 days comprises the inner system. Further analysis reveals that it is an evolved G-type star with an active chromosphere. The G star has a low-mass companion, and the third body is a hot subdwarf that excites the surrounding planetary nebula. A change in the observed systemic velocities with a period of approximately 2000 days points toward the existence of the third body. Photospheric and chromospheric disturbances on the surface of the G star account for the changeable period of light variance on the central star. The masses of all the components are calculated, and the rotational velocity of the primary component and the orbital inclination of the inner system are determined. The statistical relation between distance and apparent diameter for nebulae of this type suggests that the distance d = 100-170 pc is accurate. 26 refs.

Delta Capricorni - an evolved binary or a main-sequence binary

A synthesis method is used to analyze B and V observations of Delta Cap obtained at the Bosscha Observatory in 1984 and 1985. Both components of the binary are found to be well inside their critical Roche lobes. The data are consistent with a model using a mass radio q = 0.365 which yields a main-sequence mass for the primary star. A distance of 8-11 pc is implied. 29 references.

Synthetic analysis of light curves of the close binary system UZ Puppis

BV light curves obtained by Bookmyer (1985) have been analysed with Yamasakis synthetic technique. As some small difference exists between the light maxima, analysis has been made for the first and the second half of light curve, separately. The result indicates that system parameters deduced from the second half give a better fitting with smaller O-C residuals. These parameters reveal that UZ Pup is contact to the Roche lobe.

The Development of Astronomy and Emergence of Astrophysics in Indonesia

This chapter reviews the development of astronomy and astrophysics in Indonesia, from early times, through the Dutch era and into the recent period when Indonesian astronomy has been in the safe hands of Indonesian astronomers.

The spectral evolution of nebular phase from Nova V5668 Sgr

The spectral evolution of the Nova V5668 Sgr has been observed on 12 June, 23 June, and 15 August 2015 using NEO-R1000 spectrograph attached to the C-11 telescope at Bosscha Observatory, Lembang, Indonesia. The observed spectra indicate that the nova has been entering the nebular phase. The spectra during this phase showed strong forbidden lines of [O I] λ6300, 6364, [O II] λ7320, and [O III] λ5007, [N II] λ5755. The spectra also showed emission line of Fe II λ4924, 5169, 5317, 6149. We classify Nova V5668 Sgr into the Fe II type. We present and discuss the variation of nebular abundance N(X)/N(H) of the Nova V5668 Sgr in the light of its evolutionary stages.

Imaging and spectroscopic observations of the 9 March 2016 Total Solar Eclipse in Palangkaraya

The March 9th 2016 total solar eclipse observation was carried out at Universitas Palangkaraya, Central Kalimantan. Time-resolved imaging of the Sun has been conducted before, after, and during totality of eclipse while optical spectroscopic observation has been carried out only at the totality. The imaging observation in white light was done to take high resolution images of solar corona. The images were taken with a DSLR camera that is attached to a refractor telescope (d=66 mm, f/5.9). Despite cloudy weather during the eclipse moments, we managed to obtain the images with lower signal-to-noise ratio, including identifiable diamond ring, prominence and coronal structure. The images were processed using standard reduction procedure to increase the signal-to-noise ratio and to enhance the corona. Then, the coronal structure is determined and compared with ultraviolet data from SOHO to analyze the correlation between visual and ultraviolet corona. The spectroscopic observation was conducted using a slit-less spectrograph and a DSLR camera to obtain solar flash spectra. The flash spectra taken during the eclipse show emissions of H 4861 A, He I 5876 A, and H 6563 A. The Fe XIV 5303 A and Fe X 6374 A lines are hardly detected due to low signal-to-noise ratio. Spectral reduction and analysis are conducted to derive the emission lines intensity relative to continuum intensity. We use the measured parameters to determine the temperature of solar chromosphere.

The BIMA project: Two years report and analysis of O-C diagram on V566 Oph

The Eclipsing Binaries’ Minima Monitoring Project (BIMA) is a joint project between Institut Teknologi Bandung (ITB) and National Astronomical Research Institute of Thailand (NARIT). This project is dedicated to observe minim of eclipsing binaries light curves to derived their time of minimum. Since its commissioning in 2012, this project has secured 71 minima of more than 30 eclipising binaries until September 2014. In the first year, BIMA project has established the observational technique, data handling system, calculation for determination time of minimum, and automatization for image reduction and analysis. In the second year, BIMA project began to combine its time of minimum data with other previous observations to analyze O-C (Observed-Calculated) Diagram of all observed systems. The O-C diagram is one of indispensable tools to study evolution in eclipsing binaries in which it indicates period change or correction for periode prediction. Period changes closely related to evolutionary phase of the s...

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.

Photometric and Spectroscopic Studies of BW Eri

New CCD photometric and spectroscopic studies of eclipsing binary BW Eridani are presented. BVRI photometric observations were carried out using Bosscha’s 20-cm (f/10) GAO-ITB Remote Telescope System in 2006 and 28-cm (f/10) Schmidt–Cassegrain telescope in 2007. Low-resolution spectra R = 400 ∼ 500 were obtained using Bosscha’s 45-cm (f/12) GOTO telescope equipped with Bosscha Compact Spectrograph (Malasan et al. 2001) in optical window. The investigation of B, V , R, I light curves by fitting method yields in temperature 7, 480 ± 2, 950 K and 5, 200 ± 875 K, fractional radii 0. 491 ± 0. 126 and 0. 280 ± 0. 135, for the primary and secondary components, respectively. An inclination 89 ∘ ± 2. 2 ∘ is also deduced. We obtained the time for primary eclipse at HJD = 2453769. 1760 ± 0. 0118 by Kwee–van Woerden method, which indicate period change. At the orbital phase of 0.955 and 0.511 the star’s spectrum is consistent with spectral type G8V for the secondary and A7V for the primary, respectively.

DIVISION XII / COMMISSION 46 / PROGRAM GROUP WORLD-WIDE DEVELOPMENT OF ASTRONOMY

The Program Group for the World-wide Development of Astronomy (PG-WWDA) is one of nine Commission 46 program groups engaged with various aspects of astronomical education or development of astronomy education and research in the developing world. In the case of PG-WWDA, its goals are to promote astronomy education and research in the developing world through a variety of activities, including visiting astronomers in developing countries and interacting with them by way of giving encouragement and support.