The interaction between Io’s extended atmosphere and Jupiter magnetosphere is a strong evidence of electrodynamic interaction between intense plasma source and planetary magnetosphere. The result of this interaction is picked up current, which travels along the magnetic field line, from the vicinity of Io toward Jupiter’s magnetosphere. At the end of magnetic flux tube, spot emissions were...
This paper describes observations of GEOs satellite Thaicom series with 0.7 m telescope at Inthanon Mt., Chaingmai, Thailand. Observation took place 2 nights. Three-frame was done for each set and 2 sets were preceded for each satellite. Then the astrometry technique; LPSR (Least Square Plate Reduction) was used to get object coordinate in order to compare with well-known reference stars in...
We present computational simulation of merging between two spiral galaxies, while each galaxy has dark matter halo particles and disk particles. After the merging between two galaxies, they are expected to become an elliptical galaxy. This study uses Navarro–Frenk–White (NFW) profile and Sersic profile for describes distribution of particles. NFW profile is an approximated profile of dark...
Among time-resolved studies of compact binaries, systems including white-dwarfs are particularly challenging due to their faintness and to the short duration of the eclipses. The 2.4m Thai National Telescope (TNT) equipped with ULTRASPEC is an ideal facility for such investigations, due to a combination of sensitivity and relatively long instrument allocations. We report our work on the newly...
The interaction between Jupiter’s magnetic field and Io creates the bright spot, which is called “Io’s magnetic footprint” (IFP). This footprint is a result of plasmas, which are picked up from Io along the magnetic field line and collide with atmospheric particles in Jupiter’s ionosphere. The brightness of Io’s magnetic footprint varies according to different positions of the Io in plasma...
We have developed the lessons to help students understand the motion of celestial objects easier than before by using Stellarium program. Stellarium is a free open source planetarium program that can be run on many computer platforms and also on a tablet. It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope. It is being used in planetarium...
Selecting high redshift galaxies through their strong emission in the Lyman alpha feature using the narrow-band imaging method has come to be a very effective technique to isolate high redshift galaxies. Objects selected in this way are called Lyman Alpha Emitters (LAE). At redshift z ∼ 3, there are several hundreds of spectroscopically confirmed LAE by several groups. In this work, we...
We study thermodynamics of black holes in dRGT massive gravity. The dRGT massive gravity is a modified gravity theory in which graviton mass is given to the Einstein gravity theory while Einstein gravity theory corresponds to the theory of massless graviton. The P-V criticality and phase transition of the black hole are investigated in detail by comparing the results with the van der Waals...
Period change of binary system V1799 Orionis in this work used 0.5 meter reflecting telescope with CCD photometric system in blue, visual and infrared bands. This research was observed at Thai National Observatory, Chiang Mai. A light curve of V1799 Orionis was analyzed using program Maxlm DL5 and its period change was also calculated. The results shown that its orbital period and a continuous...
Classification criterion for identifying asteroid and comet has been developed continually for several decades. However the main concepts for the criterion remain unchanged. Comet has gas, which vaporizes from its surface when it travels into inner solar system (about 2 astronomical units). On the other hand, an asteroid does not emit gas anywhere in its orbit. The discoveries of asteroids and...
The objective of this work is to determine the probability of finding Earth-like planets orbited around Sun-like star under the condition that its inclination is not appropriate for eclipsing. The method was done by analysis of the database of transiting planets discovered by NASA’s Kepler Mission. We determined that Earth-like planet requires the following properties; Earth Similarity Index...
The difference between Thai lunar calendar and tropical solar calendar was investigated in this study. Phases of the moon regarding to Thai Lunar calendar appear to be different from the tropical solar calendar by a day in 2016. Each 19-year cycle, which is called Metonic cycle, the nearly same periods of both calendars were used to estimate the uncertainty of the time prediction for lunar...
Umbra and Penumbra Areas of Sunspot from the Solar and Heliospheric
Observatory image
Thawatchai Sudjai
Department of Physics, Mahidol Wittayanusorn School, Salaya, Phuttamonthon, Nakorn Pathom, 73170
E-mail: thawatchai@mwit.ac.th
Abstract
The areas of umbra and penumbra of sunspots can indicate the magnetic field of the Sun, and the development of the sunspot group. As the size of...
In this work, we investigate the Vainshtein mechanism in the alternative theory of gravity induced by the general disformal transformation on Einstein action. This theory of gravity is the disformal gravity. We find that the Vainshtein mechanism works well in this theory of gravity. Based on this result, we compute the post-Newtonian parameters and study the bound on these parameters.
The separate universe approach is the one of the important tools for study primordial cosmological perturbations on large scales. Since it is constructed without using of any particular theories of gravity, it is expected to valid for any covariant theories of gravity. However, recently, there is a study showing that it is valid only for some theories of gravity. In our research, we have found...
In general relativity, there exists a wormhole solution which is a region connected between two asymptotically flat spacetime regions. The wormhole solution may be obtained in a modified gravity theory and also possibly give non-trivial corrections to the one in general relativity. In this presentation, we investigate the wormhole solution in a modified gravity theory. One of interesting...
