Seminars

AAA Asteroids and Comets Short Periode in View of Tisserand

Invariant and Overall Physical Phenomenon

S.Siregar

Bosscha Observatory and Astronomy Research Division, Institut Teknologi Bandung, Indonesia

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On the orbit of visual double star Gamma Coronae Australis

( RA (J2000) =19h 06m.4 and DEC (J2000): -37o04’)

Suryadi Siregar

Bosscha Observatory and Astronomy Research Division, Institut Teknologi Bandung, Indonesia

and

Emanuel Sungging Mumpuni

Indonesian National Institute of Aeronautics and Space, Bandung, Indonesia

Abstract

In the present paper the Thiele-Innes-van den Bos for calculating the obit of Gamma Coronae Australis (g CrA) =HR 7226=SAO 210928=WDS 19064-3704A are used. The data of position angle and angular separation which used for this investigation are taken from The Washington Visual Double Star Catalog.The orbital elements driven by this method are: orbital period is, P=112.18 yr, eccentricity, e = 0.29, periastron passage, T=1999.74 year, inclination, i = 139o.1, argument of periastron, w = 317o .8, ascending node, W=30o, semimajor axis, a=1².998, semiminor axis, b=1².912. By using mass-luminosity relation we found that the mass of primary is and the mass of secondary is.

Key words: Visual Binary-Celestial Mechanics

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On the Potentially Hazardous Asteroids: Origin and Tsunami Phenomenon(*)

S.Siregar, B.Dermawan, D.Dewantara
Astronomy Research Group and Bosscha Observatory
Bandung Institute of Technology
e-mail: suryadi@as.itb.ac.id

Abstract

Recently some small celestial bodies have approached to the Earth. Asteroids with this characteristic are wellknown as Near Earth Asteroid (abbreviated as NEA). These asteroids are divided into three classes: Aten, Apollo and Amor (AAA) types. At present time more than 35000 orbital elements of NEA have been already determined. Many of them have the orbit overlapping with that of the Earth in the region of perihelion. NEA is widely believed to be continuously injected into Earth-approaching orbits from main-belt asteroids occur as consequence of energetic interasteroidal collisions. If these asteroids cross the Moon’s orbit it is more possible theycrash in to the Earth. The asteroid with this criterion named Potentially Hazardous Asteroid (PHA). The hazards of collisions with the Earth somewhat in exaggeration and the news made a little panic in the community. On these small bodies, the future positions can be calculated to a certain extent from the orbital elements. However, more dangerous are unknown, small bodies approach to the Earth without any previous notice, and the number of these unknown Earth approaching small bodies with diameter larger than 0,5 km is estimated amount to nearly 10,000. The hazards of asteroid or comet collisions are direct ones and indirect (afterward) ones. The direct hazards are a huge earthquake, a tsunami and an urban and wild fire. The indirect hazards are the large temperature drop, acid rain fall, and depletion of ozone layer. These direct hazards are local a short term, but the indirect hazards will be world wide and long duration. The worldwide temperature drop that has serious effect on photosynthesis is most important to a crop production and in turn to surviving of human being. This paper present the direct hazards in case asteroid fall into the ocean and discuss some empirical formulas about the effect of asteroid collision to the Earth

 

Key words: Asteroid-Potentially Hazardous Asteroids

(*) Seminar Sehari Astronomi, Bosscha Observatory, 15 December 2007

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Aspek Terrestrial Pada Penentuan Posisi Hilal(*)

S.Siregar
Kelompok Keahlian dan Observatorium Bosscha
Bandung Institute of Technology
e-mail: suryadi@as.itb.ac.id

Abstract

Ketelitian dalam menentukan posisi Bulan merupakan syarat penting dalam telaah hilal. Tulisan ini membahas beberapa koreksi astronomis yang diperlukan dalam mereduksi data observasi, seperti presesi, nutasi dan paralak terhadap pengamatan Bulan, maupun benda langit lainnya. Aspek ini perlu diperhatikan sebelum konklusi akhir tentang penampakan hilal diambil

Kata Kunci : Astrometri-Segitiga Bola

(*)Seminar Sehari Astronomi:Aspek Teoritis dan Obsercasi Astronomi Visibilitas Hilal, Observatorium Bosscha-ITB, Lembang 27 Mei 2006

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Seminar Himpunan Astronomi Indonesia, Lembang 12 April 2008