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Solar activity research provides insight into the Sun's past, future (Science Daily, 2018). The solar activity includes observations of large numbers of intense sunspots, flares, and other phenomena; and demands a wide range of techniques and measurements on the observations. This research needs long term data collection before critical analyses can occur, to generate meaningful learning and knowledge. In this project, we will use solar imaging to make observations of solar activity, and take our baby steps to make contributions in citizen science. Observations will be made in 3 wavelengths to gain a more thorough analysis by looking at different perspectives of the Sun, namely H-Alpha, Calcium-K, and white light. [ABSTRACT FROM AUTHOR]

Stellar streams are stars which are trapped in the same potensial caused by dynamical resonance or tidal force. We aim to analyze kinematic sub- structures (streams) in the Galactic halo by V vs √ U2+ 2V2 planes of Arifyanto & Fuchs. We crossmatched data from Gaia DR2, GALAH DR2, RAVE DR5 and LAMOST DR4 based on positions. We have 3D kinematics and metallicity data of halo stars selected from kinematics criteria from ratio of probability of thick disk (TD) over halo (H) less than 0.01. Substructures are detected by using wavelet transformation and corrected using 15 Monte Carlo simulations. We obtained four kinematic structures on V vs √U2 + 2V2 plane which two of them are associated to BB17-1 and BB17-2 streams. All the streams had a high probability from the extragalactic origin. [ABSTRACT FROM AUTHOR]

Neutrino oscillations are a possible way to probe beyond Standard Model physics. The propagation of Dirac neutrinos in a massive medium is governed by the Dirac equation modified with an effective Hamiltonian that de- pends on the number density of surrounding matter fields. At the same time, quantum nonlinearities may contribute to neutrino oscillations by further mod- ifying the Dirac equation. A possible nonlinearity is computationally studied using Mathematica at low energies. We find that the presence of a uniform, static background matter distribution may significantly alter the oscillation am- plitude and wavelength; the considered nonlinearity may further reduce both oscillation amplitude and wavelength. In addition, the presence of matter al- lows the effects of the nonlinearity to be more readily observed for the chosen background densities and neutrino energy. [ABSTRACT FROM AUTHOR]

We present a brief review of the recent results of photometric and spectroscopic surveys and 3-D hydrodynamic simulations of the mass- transfer for the class of oscillating mass-accreting components of Algols (oEA stars). These ground-based spectroscopic and space-based photometric surveys are aimed at detecting and studying the spectra of non- radial oscillations, to get precise orbits and parameters of the binaries, and studying the spectroscopic and the hydrodynamic nature of the mass- transfer. We discovered 47 new oEA stars in TESS data and carried out follow up spectroscopic observations of known and new oEA stars with the SALT telescope. We found that the co-existence of excitation of high-degree non-radial modes with a wide spectrum of low-degree modes is a common phenomenon in oEA stars. [ABSTRACT FROM AUTHOR]

In 1979, Giovannini [1] formulated multiparticle production as a manifestation of four QCD processes: A: g → gg (gluon bremsstrahlung), A-: q → qg (quark bremsstrahlung), B: g → qq (quark pair creation) and C: g → ggg (four-gluon vertex). At present, only approximate solutions exist, such as the Generalized Multiplicity Distribution (GMD) which excludes pro- cesses B and C [2, 3]. These approximate solutions have been very successful in describing charged particle multiplicities at lower energies, at least until the appearance of a shoulder-like structure at √s ≈ 200 GeV and 900 GeV first reported by the UA5 collaboration [4], also known as "KNO-scaling violation". Here, we extend the work of Sakai [5] and attempt a numerical solution that incorporates all four QCD processes, and see if the addition of processes B and C can explain the shoulder-like structure. [ABSTRACT FROM AUTHOR]

Astronomy has been practiced for as long as humans have been looking at the sky. Early civilizations used several celestial objects to do their daily activities, like doing a traditional ceremony. Ciptagelar Village is located at Sukabumi Regency, West Java, Indonesia. It has been established for almost 650 years. Ciptagelar villagers consider that a full Moon phase is a special and sacred thing. They have a welcoming ceremony for it, named Mapag Purnama. We study this activity in the way of Ethnoastronomy. The methods that we used are interviewing the villagers, including the customary leader of Ciptagelar Village, and doing a literature study. Ceremony of Mapag Purnama is held every 13rd to the night of 14th of the Moon Javanese Calendar. We use three references for choosing the date of full Moon phase, namely Fred Espenak, NASA, and Stellarium application. This date is then converted from Solar Calendar to Javanese and Hijriyah. Because Javanese Calendar is adopted from Hijriyah Calendar, both of two will have the same dates. We use 120-years correction for a difference cycle and number of leap years. However, after 2010 CE this correction is no longer valid. We find that the Javanese Calendar is one day slower than the Hijriyah Calendar. [ABSTRACT FROM AUTHOR]

A phenomenological model of particle production and hadronisation in high energy collisions is formulated using Dirac fields in Yukawa-like interaction and the resulting stochastic equation is solved numerically. Different initial conditions are used to compare particle- particle (ψ ψ) and particle-antiparticle (ψ* ψ) interactions. It is shown that in this simplified view, there is a clear difference between the final multiplicity distributions resulting from the two initial conditions. To model the restricted phase space (limited pseudorapidity) measurements in experiment, a "loss" function is also proposed to account for the undetected particles close to the beam line. [ABSTRACT FROM AUTHOR]

A phenomenological model describing the transverse energy distribution (ET) of nuclear collisions is first studied in detail by fitting it on ET data for O-Pb collisions at √sNN = 200 GeV per nucleon obtained from the NA35 collaboration. Next, the model is used to fit the ET data for Pb-Pb collisions at LHC energies of √sNN = 2.76 TeV per nucleon obtained from the ATLAS collaboration. From the fits, we determine an upper bound for the energy density for Pb-Pb collisions at LHC energies of √sNN = 2.76 TeV per nucleon. [ABSTRACT FROM AUTHOR]

Sudden ionospheric disturbances are transient changes in the ionosphere caused by enhancement in X-ray and EUV fluxes during solar flare events. The Solar Storm Radio Telescope is developed to detect Very Low Frequency (VLF) signals with frequency between 3-30 kHz transmitted from various VLF stations around the Globe. We will also be investigating different methods to reduce the background noise in the data collection. This will help to ensure an accurate hit when there is a sudden ionospheric disturbance. [ABSTRACT FROM AUTHOR]

The warp in Milky Way seen through the young stellar disk shows the complex structures. Its spatial distribution reveals the asymmetry in the vertical distance to the galactic midplane, whereas the kinematics shows the os- cillating motion. We analyze the warp using about 25,000 OB stars from Gaia Data Release 2, with Galactocentric azimuth (φ) range from 135◦ to 225◦. We detect the warp from two distinctive regions. First region (warp down) lies on 100◦ < l < 150◦ and second regions (warp up) lies on 150◦ < l < 220◦. The vertical position towards the Galactic midplane (Z) from all samples shows the line-of-nodes of the warp is on φ = 174◦ ± 2◦. The maximum deviation in warp down region reachs 0.1 kpc and 0.2 kpc in warp up region. The vertical velocity (VZ) from both regions are dominated by negative VZ. From the kinematics dis- tribution, it can be concluded that there is an oscillati1ng motion. Considering with the previous study, the oscillating motion was caused by the gravitational interaction with the Galaxy satellites. From this, we can constrain the origin of the warp is developing from the tidal interaction between Milky Way and its satellites. [ABSTRACT FROM AUTHOR]

It has been shown recently that additional information can be ob- tained from charged particle multiplicity distribution by investigating their mod- ified combinants C j, which exhibit periodic oscillatory behaviour. The modified combinants obtained from experimental data can be expressed in a recurrent form involving the probability of obtaining N charged particles P(N), scaled by the void probability P(0). The effects of various experimental observables such as |η|, pT and centre-of-mass collision energy √s on the oscillations of C j will be discussed. [ABSTRACT FROM AUTHOR]

The measured and predicted variables of pulsar PSR B1937+21 were explored from the energetics obtained from the previous observation made. The target parameters such as the brightness, luminosities, and optical efficiency. A series of observations were analysed to determine the individual values of the parameters chosen. Within the extended area of optical pulsation, the values were plotted to determine the relation of it to synchrotron emission. The results were presented graphically to see whether PSR B1937+21 will remain consistent with the expected pulsar model. The researcher suggests that simulation and correlation of previous observation made together with a new one to explore the cause of optical pulsation from mass transfer and spectral evolution. [ABSTRACT FROM AUTHOR]

We analyze the spectral evolution of ultraluminous X-ray source (ULX) M82 X-1 by means of spectral fitting. We use selected Swift/XRT data in 2014 and 2015. The flux of M82 X-1 increased by a factor of 2-3 from 2014 to 2015. Most of the data in 2015 show greater dominance of hard component than those of 2014. Due to moderate signal-to-noise ratio, we only fit each spectrum with power-law and disk blackbody model separately. The data in 2014 are better fitted with powerlaw model based on the value of reduced-chi squared. On the other hand, both powerlaw and diskbb models showed comparable re- duced chi-squared value for the data in 2015. We found that the range of spectral index for 2014 data is 1.65 < Γ < 2.08 and for 2015 data is 1.02 < Γ < 1.95 from the powerlaw model, resembling the range for that of black hole binary system at low mass accretion rate. We obtained higher innermost disk temper- ature from the disk blackbody model, 1.20 keV < Tin < 3.63 keV, compared to that of black hole binary system in the thermal state. The calculated innermost radius of the disk, Rin, varies between 0.99 to 4.89 RS assuming 10 M0 black hole which indicates that the spectral state is not in thermal dominant state but rather we suspect that M82 X-1 exhibits greater mass accretion rate than that of the thermal dominant state. [ABSTRACT FROM AUTHOR]

A strong and stable magnetic field covering the whole surface is a landmark of chemically peculiar or CP stars. To explain the origin of mag- netic stars, several hypotheses were proposed, which depending on the mech- anism and time of formation can be grouped into three main. The magnetic field may originate in the protostellar medium ("fossil field"), turbulent layers of a star ("dynamo" mechanism) or in the other environment. In either scenario, binary stars appear as a merit of its reliability. Recent advances in observational astrophysics uncovered a bunch of new binary magnetic stars that were considered as rare before. We outline the results of studies of exotic binary and multiple systems with magnetic CP components: HD 6757, HD 34736, and HD 40759. [ABSTRACT FROM AUTHOR]

Low-frequency radio telescopes are cheap and useful devices for the investigation of terrestrial and extra-terrestrial emissions. These emissions come either from the Sun and the planet Jupiter to terrestrial emissions. This project aims to investigate the Very Low Frequency (VLF) waves from mid-August to October 2019 using Radio JOVE (20 MHz) and SSID (3-30 kHz) to observe for the occurrence of solar flares and see how if the radio telescopes that the team set up is reliable. This will allow us future students aspiring to learn about astronomy to examine solar flares in detail during the upcoming solar maximum. Not many flares were detected as this period happens to be a solar minimum. However, a series of flares occurred between 30 September 2019 and 1 October 2019, which the telescopes have been able to detect, particularly SSID. [ABSTRACT FROM AUTHOR]

Millimetre ALMA observations of the nascent winds of several Oxygen rich AGB stars have revealed the high Doppler velocity wings in their spectra. However, the physics underlying their production is unclear. In this paper, we illustrate the argument with four examples of oxygen-rich AGB stars: EP Aqr, R Dor, L2 Pup and Mira Ceti. [ABSTRACT FROM AUTHOR]

Local dark matter density, ρdm, is one of the crucial astrophysical inputs for the estimation of detection rates in dark matter direct search experi- ments. Knowing the value also helps us to investigate the shape of the Galactic dark halo, which is of importance for indirect dark matter searches, as well as for various studies in astrophysics and cosmology. In this work, we performed kinematics study of stars in the solar neighborhood to determine the local dark matter density. As tracers we used 95,543 K-dwarfs from Gaia DR2 inside a heliocentric cylinder with a radius of 150 pc and height 200 pc above and below the Galactic mid plane. Their positions and motions were analyzed, assum- ing that the Galaxy is axisymmetric and the tracers are in dynamical equilib- rium. We applied Jeans and Poisson equations to relate the observed quantities, i.e. vertical position and velocity, with the local dark matter density. The tilt term in the Jeans equation is considered to be small and is therefore neglected. Galactic disk is modelled to consist of a single exponential stellar disk, a thin gas layer, and dark matter whose density is constant within the volume consid- ered. Marginalization for the free parameters was performed with Bayesian theorem using Markov Chain Monte Carlo (MCMC) method. We find that ρdm = 0.0116 ± 0.0012 MO/pc or ρdm = 0.439 ± 0.046 GeV/cm3, in agreement within the range of uncertainty with results of several previous studies. [ABSTRACT FROM AUTHOR]

Investigation of spectral evolution of four black hole candidates was carried out by using color-color diagram as well as spectral fitting on Swift/XRT data. Newly found candidates, which are classified as low-mass X-ray binary system based on their transient nature, are the focus of our work. We compare their spectral evolutions to that of XTE J1752-223, a transient system and a more convincing black hole candidate whose mass has been determined from spectral-timing correlation scaling. In addition, comparison to Cygnus X-1, a well-known stellar-mass black hole, was done despite its persistent nature. The spectral fitting, by using a combination of thermal disk and non-thermal component model, results in the innermost temperature values in the range of the typical innermost temperature of black hole binary which is 0.7 – 1.5 keV. The spectral evolutions of the candidates bear a resemblance to both Cygnus X-1 and XTE J1752-223. We note that during Swift/XRT observations, the spectra of Cygnus X-1 and IGR J17451-3022 are mostly dominated by the non- thermal component. We conclude that the compact object of MAXI J1535- 571 and MAXI J1828-249 is highly likely to be a black hole. However, the lack of data rendered conclusive result impossible for IGR J17454-2919. [ABSTRACT FROM AUTHOR]

A Total Solar Eclipse is one of the astronomical world's most awe-inspiring phenomena. It is a relatively rare astronomical event that lasts at most a few minutes and can be viewed only at very specific times and from very specific locations on the globe. Capturing and documenting the event so that it can be shared with others is exceptionally challenging because of its rarity and brevity. This article addresses some of the challenges and possible solutions with the use of various forms of technology as well as program management skills. [ABSTRACT FROM AUTHOR]

The research and training team of the Department of Astrophysics (DAP), Vietnam National Space Center, is some twenty years old. Currently, we work in the fields of stellar physics and high-redshift galaxies using mm/sub-mm data observed by world-leading radio interferometers such as ALMA and NOEMA. In this report, we present the research team and its activities and give illustrations of the research work with emphasis on the use of archival data. [ABSTRACT FROM AUTHOR]

We review an improved maximum likelihood analysis of the Type 1a Supernova (SNe1a) data. We calculate the profile likelihood in the Ωm -ΩΛ pa- rameter space by conducting a parameter sweep across the 8 SNe1a parameters, using a Markov Chain Monte Carlo (MCMC) optimization algorithm. This im- proved analysis, which does not assume arbitrary values for the uncertainties, has the advantage of being bias-free as compared to the original analysis. We use the Joint Lightcurve Analysis (JLA) dataset containing 740 SN1a data sam- ples for our study, and compare among 5 different models: the ΛCDM model, the flat wCDM model, its non-flat generalization, as well as two dynamical w(z) parametrizations. We find that the ΛCDM model is favoured over the other models, and the best fit values based on this model are Ωm =0.40 and ΩΛ =0.55. Interestingly, in most of the contour plots we obtain, the line of no acceleration is crossed at 2∼3σ confidence levels, which is similar to the results published by Nielsen et al, the original authors who introduced the improved maximum like- lihood analysis. When we generalize the wCDM model to the dynamical w(z) parametrizations, the evidence for cosmic acceleration becomes even weaker. This raises the question of how secure we can be of an accelerating expansion of the universe. [ABSTRACT FROM AUTHOR]

High-resolution solar imaging, essential for research into the Sun is usually limited to high-end expensive telescopes found in professional observatories using adaptive optics technology. However, a Schmidt-Cassegrain Telescope (SCT) or a refractor telescope equipped with a narrow-band energy rejection filter and a suitable solar spectrum filter, employing appropriate data acquisition and post-processing techniques can provide an amateur astronomer a costeffective means to high-resolution solar imaging. [ABSTRACT FROM AUTHOR]

In this paper, we reconstruct matter power spectrum of a cosmological model in which coupled scalar field acts as dark energy. The coupled scalar field (CSF) dark energy we propose here is a generalized model of quintessence, k-essence or phantom coupled to dark matter (non-baryonic matter) via a coupling constant. The existence of coupling between dark energy and matter allows energy to transfer between them, which may give rise to different observational signatures, especially at perturbation level, including matter power spectrum. In this work, through analytical exploration we studied that possible signature in matter power spectrum that maybe induced by this mode. [ABSTRACT FROM AUTHOR]

We discuss an alternative picture of neutrino oscillation. In this phenomenological model, the flavor-changing phenomena of massless neutrinos arise from scattering processes between neutrinos and four types of undetected spin-0 massive particles pervading throughout the Universe, instead of neutrinos' own nature. These scattering processes are kinematically similar to Compton scattering. One type of left-handed massless sterile neutrino is needed in order to reproduce the neutrino oscillation modes predicted in the theory of neutrino mixing. Implications of our model include the existence of sterile neu- trinos, the nonconservation of active neutrinos, the possible mismatch among three neutrino mass squared differences ∆m2ij interpreted in the theory of neutrino mixing, the spacetime dependence of neutrino oscillation, and the impossibility of neutrinoless double beta decay. Several important open problems in neutrino physics become trivial or less severe in our model, such as the smallness of neutrino masses, neutrino mass hierarchy, the mechanism responsible for neutrino masses, and the Dirac/Majorana nature of neutrinos. [ABSTRACT FROM AUTHOR]