Stellar Physics

The basics of all gravitating bodies are the same in the cosmos, may it be a giant star, a small star, a planet, a human embryo, or a rice seed. Gravity is traditionally considered a long-range force, but the latest findings show that gravity operates even at short ranges of mass1. We assume that gravity or intrinsic gravitation compresses masses to a focal point or center. Due to intermolecular collision among the particles of mass heat is generated that is normal to be higher in the core and gets radiated away towards the periphery to achieve thermodynamic equilibrium with its environment. The core is hot in stars, but away from the core frost develops. In the Earth system, the core in the deep layer is hot and radiates to the mantle and outer layer crust. The pattern of heat transfer is different in each layer. In Earth's system, heat is radiated from the inner to the outer core through conduction, from the lower to upper mantle through convection, or return to the original is prominent between the lower and upper mantle Core temperature Identically, in the human embryo, there are also three germ layers viz. Endoderm, Mesoderm and ectoderm. The organs develop and maintain a distinct temperature lineage of independent germ layers.
Here we explain how a human embryo is activated on being estranged from the surrounding external gravitational field due to fluids, gets compressed, and exhibits an identical pattern of heat transfer including neurulation and brain formation through the eruption mechanism within the human zygote, as in the formation of a volcano, movement of plate tectonics in the Earth system.
1.      Rothleitner C. Ultra-weak gravitational field detected. Nature. 2021 Mar;591(7849):209-210. doi: 10.1038/d41586-021-00591-1. PMID: 33692552

The Stellar Imager (SI) is envisioned as a space-based, UV-optical interferometer composed of 10 or more onemeter class elements distributed with a maximum baseline of 0.5 km. It is designed to image stars and binaries with sufficient resolution to enable long-term studies of stellar magnetic activity patterns, for comparison with those on the sun. It will also support asteroseismology (acoustic imaging) to probe stellar internal structure, differential rotation, and large-scale circulations. SI will enable us to understand the various effects of the magnetic fields of stars, the dynamos that generate these fields, and the internal structure and dynamics of the stars. The ultimate goal of the mission is to achieve the best-possible forecasting of solar activity as a driver of climate and space weather on time scales ranging from months up to decades, and an understanding of the impact of stellar magnetic activity on life in the Universe. In this paper we describe the scientific goals of the mission, the performance requirements needed to address these goals, the "enabling technology" development efforts being pursued, and the design concepts now under study for the full mission and a possible pathfinder mission.

COLLABORATION, NATIONAL SUPERCONDUCTING CYCLOTRON LABORATORY COLLABORATION-Recent studies on the discrepancy of Z = 38-47 abundances between metal poor stars have proposed (α, xn) reactions as the main reaction pathway for early nucleosynthesis in the wind with the condition of (n, γ) − (γ, n) equilibrium and temperatures between 3.5 and 5.5 GK. Uncertainties in (α, xn) reaction rates directly affect calculated abundances with an impact that is comparable to that from astrophysical uncertainties. At present, reaction rate uncertainties are relatively large since little experimental data exists for (α, xn) cross sections involved in the nucleosynthesis calculation. We are developing a neutron detector which counts emitted neutrons from the (α, xn) reactions. The detector consists of 80 gas-filled BF 3 and 3 He proportional tubes oriented in rings along the beam axis embedded in a polyethylene matrix. The configuration of the tubes in the matrix is determined by both a high average neutron detection efficiency and the efficiency as a function of energy to be as constant as possible from E n = 0.1-19.5 MeV, since neutron energy information will be lost due to neutron moderation. Details of the detector design and a status report on the device will be presented.

In Newtonian gravitational physics, as currently understood, the spin of a gravitating body has no effect on the nature of the gravitational field emergent from this gravitating body. This position has been questioned by the Azimuthally Symmetric Theory of Gravitation (ASTG-model; in Nyambuya $2010$). From the ASTG-model -- which is a theory resulting from the consideration of the azimuthally symmetric solutions of the well known and well accepted Poisson-Laplace equation for gravitation, it has been argued that it is possible to explain the unexpected perihelion shift of Solar planetary orbits. However, as it stands in the present, the ASTG-model suffers from the apparent diabolic defect that there are unknown parameters ($\lambda$'s) in the theory that up to now have not been able to be adequately deduced from theory. If this defect is not taken care of, it would consume the theory altogether, bringing it to a complete standstill, to nothing but an obsolete theory. Effort in r...

The photon entropy production Σ γ is an extensive quantity and thus is fundamentally a volume integral of its local density σ γ. Re-expression of Σ γ as a surface integral is effected through the divergence theorem and the surface photon entropy flux H. This step requires the photons to propagate freely from a well-defined surface. Below this surface, the photons diffuse through matter instead. In this case, of a star with a sharp surface of temperature T eff and no atmosphere, the paragraphs surrounding equations (3.10) and (A.10) incorrectly present the surface integral form of Σ γ ("the total boundary entropy production, Σ bound ") as an additional contribution to Σ γ. In fact the boundary expression is simply the total Σ γ within the enclosed volume, including all entropy production due to luminosity production and transport. The volume integrals (3.9) and (A.10) are the photon entropy production up to, but not including, the surface; the surface integral or boundary term (3.10) is the photon entropy production including the surface, as well as the interior.

Several critical issues recently raised by observations of SN 1987A are addressed. These include: 1) the evolution of the pre-supernova star, why it was blue, what its composition and core structure were; 2) the detailed isotopic composition of the ejecta; 3) why and to what extent the supernova composition was mixed in velocity space; 4) the interpretation of recently observed infrared lines, especially their profiles and the existence of red-shifted ‘wings’; and 5) what has become of the neutron star.

We present the first calculations to follow the evolution of all stable nuclei and their radioactive progenitors in stellar models computed from the onset of central hydrogen burning through explosion as Type II supernovae. Calculations are performed for Pop I stars of 15, 19, 20, 21, and 25 M ⊙ using the most recently available experimental and theoretical nuclear data, revised opacity tables, neutrino losses, and weak interaction rates, and taking into account mass loss due to stellar winds. A novel "adaptive" reaction network is employed with a variable number of nuclei (adjusted each time step) ranging from ∼ 700 on the main sequence to 2200 during the explosion. The network includes, at any given time, all relevant isotopes from hydrogen through polonium (Z = 84). Even the limited grid of stellar masses studied suggests that overall good agreement can be achieved with the solar abundances of nuclei between 16 O and 90 Zr. Interesting discrepancies are seen in the 20 M ⊙ model and, so far, only in that model, that are a consequence of the merging of the oxygen, neon, and carbon shells about a day prior to core collapse. We find that, in some stars, most of the "p-process" nuclei can be produced in the convective oxygen burning shell moments prior to collapse; in others, they are made only in the explosion. Serious deficiencies still exist in all cases for the p-process isotopes of Ru and Mo.

1. Introduction The subject Microbiology is the field of biological science that studies the microscopic organisms, for example, bacteria, viruses, archaea, prions, algae, fungi, and protozoa. These microorganisms are together known as 'microbes' (Microbiology, n.d.). The microbes are responsible for biodegradation/bio deterioration, nutrient cycling, food spoilage, climate change, the origin and resistor of disease, and biotechnology (Microbiology Society, n.d.). Microbiology research has always been predominant area of research in India, because it is vital to consulting several contemporary global objectives and challenges, such as upholding the safety of food, water, and energy for a healthy population on the inhabitable earth (Lal, 2012). As a subject microbiology is growing due to the vast research enduring in various facades in the world (Gillen and Oliver, 2012). Following to this, there is a radical growth of research output through numerous formats such as journal ...

We address the problem of how to test whether an observed solar hard X-ray bremsstrahlung spectrum (I ()) is consistent with a purely thermal (locally Maxwellian) distribution of source electrons, and, if so, how to reconstruct the corresponding differential emission measure (ξ (T)). Unlike previous analysis based on the Kramers and Bethe-Heitler approximations to the bremsstrahlung cross-section, here we use an exact (solid-angle-averaged) cross-section. We show that the problem of determining ξ (T) from measurements of I () invOlves two successive inverse problems: the first, to recover the mean source-electron flux spectrum (F(E)) from I () and the second, to recover ξ (T) fromF(E). We discuss the highly pathological numerical properties of this second problem within the framework of the regularization theory for linear inverse problems. In particular, we show that an iterative scheme with a positivity constraint is effective in recovering δ-like forms of ξ (T) while first-order Tikhonov regularization with boundary conditions works well in the case of power-lawlike forms. Therefore, we introduce a restoration approach whereby the low-energy part ofF(E), dominated by the thermal component, is inverted by using the iterative algorithm with positivity, while the high-energy part, dominated by the power-law component, is inverted by using first-order regularization. This approach is first tested by using simulatedF(E) derived from a priori known forms of ξ (T) and then applied to hard X-ray spectral data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI).

One of the areas in bibliometric research concerns the application of most commonly used bibliometric laws such as Bradford's Law of Scattering. The paper gives a review of the scholarly contribution on the various facets of Bradford's Law. In addition to the theoretical aspects of the law, review covers papers dealing with the application of the law in the various subject fields. A study on five-year data of journals (2004-2008) cited by the physicists at the Indian Institute of Science (IISc), Bangaluru was carried out to examine the applicability of Bradford's Law of Scattering, which include 690 periodicals containing 11,319 references collected from 79 doctoral theses during the period 2004-08. Ranked list of journals was prepared, and Physical Review-B with 9.53 per cent citation, followed by Physical Review-A with 7.69 per cent, and Astrophysical Journal with 5.47 per cent citations were the most preferred journals. Applicability of Bradford's Law in various methods was tested. The journal distribution pattern of the IISc doctoral theses does not fit the Bradford's distribution pattern. The Bradford multipliers were calculated, and the law found to be applicable with the value of k as 1.2. The distribution of the journals in three zones was made and the number of references in each zone was then estimated. The applicability of Leimkuhler model was also tested with the present data.

As a cool star evolves, it loses mass and angular momentum due to magnetized stellar winds that affect its rotational evolution. This change has consequences that range from the alteration of its activity to influences over the atmosphere of any orbiting planet. Despite their importance, observations constraining the properties of stellar winds in cool stars are extremely limited. Therefore, numerical simulations provide a valuable way to understand the structure and properties of these winds. In this work, we simulate the magnetized winds of 21 cool main-sequence stars (F-type to M-dwarfs) using a state-of-the-art 3D MHD code driven by observed large-scale magnetic field distributions. We perform a qualitative and quantitative characterization of our solutions, analysing the dependencies between the driving conditions (e.g. spectral type, rotation, and magnetic field strength) and the resulting stellar wind parameters (e.g. Alfvén surface size, mass-loss rate, angular momentum loss...

During the last decades, numerous observational and theoretical efforts in the study of solar oscillations, have brought to a detailed knowledge of the interior of the Sun. While this discipline has not yet exhausted its resources and scientists are still working on further refinements of the solar models and to solve the numerous still open questions, Asteroseismology, which aims to infer the structural properties of stars which display multimode pulsations, has just entered in its golden age. In fact, the space missions CoRoT and Kepler dedicated to the observation of stellar oscillations, have already unveiled primary results on the structural properties of the stars producing a revolution in the way we study the stellar interiors. Here, the modern era of Helio-and Asteroseismology is reviewed with emphasis on results obtained for the Sun and its solar-like counterparts.

In spite of the huge advances in exoplanet research provided by the NASA Kepler Mission, there remain only a small number of transit detections around evolved stars. Here, we present a reformulation of the noise properties of red-giant stars, where the intrinsic stellar granulation and the stellar oscillations described by asteroseismology play a key role. The new noise model is a significant improvement on the current Kepler results for evolved stars. Our noise model may be used to help understand planet detection thresholds for the ongoing K2 and upcoming TESS missions, and serve as a predictor of stellar noise for these missions. As an application of our noise model, we explore the minimum detectable planet radii for red giant stars, and find that Neptune-sized planets should be detectable around low-luminosity red giant branch stars.

We characterize the population of blue horizontal-branch (BHB) stars in the bulge-halo transition region of the Milky Way using the VISTA Variables in the Vía Láctea (VVV) ESO Public Survey data. The selection of BHB stars is made using the globular cluster M22 as a reference standard, and constructing color-magnitude and color-color diagrams with specific cuts in the ZY JHK s near-infrared (IR) passbands. A total of 12,554 BHB stars were detected, in a region within −10.0 • ≤ ≤ 10.2 • and −10.2 • ≤ b ≤ −8.0 •. We provide accurate coordinates and near-IR photometry for this sample of BHB stars. We searched for over-densities of stars with sizes similar to those of known globular clusters and stellar streams. By comparing real data with Monte Carlo simulations, we conclude that the few over-densities detected are of low significance. We also constructed K s-band light curves for the BHB stars to study their variability. Taking an average of 52 epochs to calculate periods and amplitudes, we identify hundreds of candidate eclipsing binaries and a dozen pulsating stars. Finally, we made some comparisons with results obtained in a previous study for RR Lyrae variable stars in this same region.

We present wind models of 10 young Solar-type stars in the Hercules-Lyra association and the Coma Berenices cluster aged around ∼0.26 and ∼0.58 Gyr, respectively. Combined with five previously modelled stars in the Hyades cluster, aged ∼0.63 Gyr, we obtain a large atlas of 15 observationally based wind models. We find varied geometries, multi-armed structures in the equatorial plane, and a greater spread in quantities such as the angular momentum loss. In our models, we infer variation of a factor of ∼6 in wind angular momentum loss $\dot{J}$ and a factor of ∼2 in wind mass-loss $\dot{M}$ based on magnetic field geometry differences when adjusting for the unsigned surface magnetic flux. We observe a large variation factor of ∼4 in wind pressure for an Earth-like planet; we attribute this to variations in the ‘magnetic inclination’ of the magnetic dipole axis with respect to the stellar axis of rotation. Within our models, we observe a tight correlation between unsigned open magnetic...

The realistic simulation of variable star populations is fundamental to determine the selection function and contamination in existing and upcoming multi-epoch surveys. We present ELLISA, a simulator that produces an ensemble of mock light curves for a population of eclipsing binaries obtained from physical and orbital parameters consistent with different Galactic populations, and which considers user-supplied time sampling and photometric errors to represent any given survey. We carried out a search for eclipsing binaries in the QUEST low Galactic latitude catalogue of variable stars, spanning an area of 476 deg 2 at −25 • b 30 • and 190 • ≤ l ≤ 230 • towards the Galactic anticentre, and use ELLISA to characterize the completeness of the resulting catalogue in terms of amplitudes and periods of variation as well as eclipsing binary type. The resulting catalogue consists of 1125 eclipsing binaries, out of which 179, 60, and 886 are EA, EB, and EW types, respectively. We estimate, on average, 30 per cent completeness in the period range 0.25 P /d 1 for EB+EW binaries and 15 per cent completeness for EA binaries with periods 2 P /d 10, being the time sampling the primary factor determining the completeness of each type of eclipsing binary. This is one of few eclipsing binary catalogues reported with an estimate of the selection function. Mock eclipsing binary light-curve libraries produced with ELLISA can be used to estimate the selection function and optimize eclipsing binary searches in upcoming multiepoch surveys such as Gaia, the Panoramic Survey Telescope and Rapid Response System, the Zwicky Transient Factory, or the Large Synoptic Survey Telescope.

The strong energetic particles ejected during sun’s activity will propagate towards earth and contribute to solar radio bursts. These solar radio bursts can be detected using CALLISTO system. The open website of the NASA provides us the data including CALLISTO, TESIS, solar  monitor,  SOHO  and  space  weather.  The type  III  and  II  solar radio  burst  on  9th November 2015 due to M3.9 class solar flare and coronal mass ejections event has expected to cause the geomagnetic storm on 11th November 2015. The geomagnetic storm reached the Earth a day earlier than expected date due to high speed coronal mass ejections that more than 950 km/s and high energy of ejected particle that causes the M3.9 class flare and coronal mass ejections. The geomagnetic storm luckily does not give high impact on earth because the event on sun, which triggered this storm not heading toward earth. Keywords: solar radio burst; coronal mass ejections; geomagnetic storm; solar flare

1. Introduction The subject Microbiology is the field of biological science that studies the microscopic organisms, for example, bacteria, viruses, archaea, prions, algae, fungi, and protozoa. These microorganisms are together known as 'microbes' (Microbiology, n.d.). The microbes are responsible for biodegradation/bio deterioration, nutrient cycling, food spoilage, climate change, the origin and resistor of disease, and biotechnology (Microbiology Society, n.d.). Microbiology research has always been predominant area of research in India, because it is vital to consulting several contemporary global objectives and challenges, such as upholding the safety of food, water, and energy for a healthy population on the inhabitable earth (Lal, 2012). As a subject microbiology is growing due to the vast research enduring in various facades in the world (Gillen and Oliver, 2012). Following to this, there is a radical growth of research output through numerous formats such as journal ...

Underground Nuclear Astrophysics Experiment in China (JUNA) has been commissioned by taking the advantage of the ultra-low background in Jinping underground lab. High current mA level 400 KV accelerator with an ECR source and BGO detectors were commissioned. JUNA studies directly a number of nuclear reactions important to hydrostatic stellar evolution at their relevant stellar energies. In the first quarter of 2021, JUNA performed the direct measurements of 25Mg(p,γ)26Al, 19F(p,α)16O, 13C(α,n)16O and 12C(α,γ)16O near the Gamow window. The experimental results reflect the potential of JUNA with higher statistics, precision and sensitivity of the data. The preliminary results of JUNA experiment and future plan are given.

A new planet has been recently discovered around Proxima Centauri. With an orbital separation of ∼1.44 au and a minimum mass of about , Proxima c is a prime direct imaging target for atmospheric characterization. The latter can only be performed with a good understanding of the space environment of the planet, as multiple processes can have profound effects on the atmospheric structure and evolution. Here, we take one step in this direction by generating physically realistic numerical simulations of Proxima’s stellar wind, coupled to a magnetosphere and ionosphere model around Proxima c. We evaluate their expected variation due to the magnetic cycle of the host star, as well as for plausible inclination angles for the exoplanet orbit. Our results indicate stellar wind dynamic pressures comparable to present-day Earth, with a slight increase (by a factor of 2) during high-activity periods of the star. A relatively weak interplanetary magnetic field at the distance of Proxima c leads ...

Context. Studying the spots of late-type stars is crucial for distinguishing between the various proposed dynamo mechanisms believed to be the main cause of starspot activity. For this research it is important to collect observation time series that are long enough to unravel both long- and short-term spot evolution. Doppler imaging is a very efficient method for studying spots of stars that cannot be angularly resolved.Aims. High-resolution spectral observations during 1994–2017 are analysed in order to reveal long- and short-term changes in the spot activity of the FK Comae-type subgiant HD 199178.Methods. Most of the observations were collected with the Nordic Optical Telescope. The Doppler imaging temperature maps were calculated using an inversion technique based on Tikhonov regularisation and utilising multiple spectral lines.Results. We present a unique series of 41 temperature maps spanning more than 23 years. All reliable images show a large cool spot region centred near th...

During a measurement campaign in winter 2006 spectrum measurements were done at difierent loca- tions in India and Sibiria. This report describes the results of Badary solar radio telescope (SSRT) site in Sibiria (Russian Federation). Measurements were done with a broadband logarithmic periodic antenna of the site con- nected to a Callisto spectrometer designed and built by ETH Zurich (Benz, 2004). This measurement campaign shall be the technical basis to decide how to continue concerning spectroscopic measurements below 1GHz with existing antennas and/or new ones. The results are presented, compared with Switzerland and discussed in form of digitally zoomed spectrums in the most interesting radio astronomy frequency ranges. In terms of electromag- netic interference Badary is much better than Switzerland and thus ideal for low frequency solar radio astronomy observations (spectroscopy).

Context. The dynamo processes in cool active stars generate complex magnetic fields responsible for prominent surface stellar activity and variability at different time scales. For a small number of cool stars magnetic field topologies were reconstructed from the time series of spectropolarimetric observations using the Zeeman Doppler imaging (ZDI) method, often yielding surprising and controversial results. Aims. In this study we follow a long-term evolution of the magnetic field topology of the RS CVn binary star II Peg using a more self-consistent and physically more meaningful modelling approach compared to previous ZDI studies. Methods. We collected high-resolution circular polarisation observations of II Peg using the SOFIN spectropolarimeter at the Nordic Optical Telescope. These data cover 12 epochs spread over 7 years, comprising one of the most comprehensive spectropolarimetric data sets acquired for a cool active star. A multi-line diagnostic technique in combination with a new ZDI code is applied to interpret these observations. Results. We have succeeded in detecting clear magnetic field signatures in average Stokes V profiles for all 12 data sets. These profiles typically have complex shapes and amplitudes of ∼10 −3 of the unpolarised continuum, corresponding to mean longitudinal fields of 50-100 G. Magnetic inversions using these data reveals evolving magnetic fields with typical local strengths of 0.5-1.0 kG and complex topologies. Despite using a self-consistent magnetic and temperature mapping technique, we do not find a clear correlation between magnetic and temperature features in the ZDI maps. Neither do we confirm the presence of persistent azimuthal field rings found in other RS CVn stars. Reconstruction of the magnetic field topology of II Peg reveals significant evolution of both the surface magnetic field structure and the extended magnetospheric field geometry on the time scale covered by our observations. From 2004 to 2010 the total field energy drastically declined and the field became less axisymmetric. This also coincided with the transition from predominantly poloidal to mainly toroidal field topology. Conclusions. A qualitative comparison of the ZDI maps of II Peg with the prediction of dynamo theory suggests that the magnetic field in this star is produced mainly by the turbulent α 2 dynamo rather than the solar αΩ dynamo. Our results do not show a clear active longitude system, nor is there evidence of the presence of an azimuthal dynamo wave.

As reviewed by Kholopov (1968), star counts for a variety of open clusters reveal the existence of low density coronal regions surrounding the nuclear concentrations of most star clusters. Such cluster coronae have diameters 2.5 to 5 times larger than the respective nuclear diameters for clusters which are poor to medium-rich in member stars, and have star densities only about 10% those observed in cluster nuclei. Cluster coronae therefore contain roughly 40% to 70% of the stars in an open cluster, and are subsequently a (or, more appropriately, the) major component of most star clusters.

The short period and small amplitude of pulsation for the 1d.95 Cepheid SU Cas make it an excellent candidate for pulsation in a purely excited mode, and, as summarized by Gieren (1982), there is some evidence from recent radius determinations for this variable which suggests that it is indeed an overtone pulsator.

Asteroseismology is interpreted as an extension of the field of variable stars, and not just as the stellar analogue of helioseismology. The main effects of stellar mass and evolution on oscillation frequencies are discussed with the help of simplified wavepropagation diagrams. Frequency separations resulting from asymptotic expressions are compared with the corresponding results from numerical computations. The validity of asymptotic theory can be gauged in this way. The seismological issues of solai-like stars and Ap stars are discussed in some detail, and a progress report on the equation of state for stellar interiors is given. The review ends with a summary of properties and important physical problems for selected classes of variable stars.

Sun is constantly produced mass and radiation during its natural activities, which will interact with ionosphere and affect the earth weather. In radio astronomer community, CALLISTO is used to capture the radio signal comes from solar activities such as solar burst. Solar flares and Coronal Mass Ejections (CMEs) were closely associated with the production of solar radio burst Type II and III. However, the determination of solar burst existence is done manually using spectrograph which appears for every 15 minutes. In order to assist the solar radio researcher to speed up the process of solar burst identification and detection, this work presents a new algorithm to auto classify solar radio burst Type II and III. The value of frequency drift was used as the main idea in this auto classify algorithm because it can easily implemented using MATLAB. There are three main steps involved named as pre-processing, identification and classification. Auto calculation of frequency drift burst on spectra was obtained from two parts which are frequency axis (df) and time axis (dt). The results of the frequency drift implementation in classification algorithm show that the algorithm developed gave almost similar determination as in manual detection. However, there are always have rooms for improvement for better detection system in future which may include specific characterization of bursts and improved noise elimination.

We present the analysis of the x-ray spectrum between 9.5 and 17.0 A of a laser-produced iron plasma. Wavelengths and relative intensities for 96 lines are measured. For the strongest part of the spectrum, above 13 A, almost all of the observed lines are identified as radiation from Fe" ", Fe" "', and Fe"'" ions. Measurements were made with a curved-crystal spectrograph. Calculations were full intermediate coupling, Hartree-Fock with relativistic corrections. Coulomb-approximation oscillator strengths were used to help in the line identification.

We summarise recent developments in modelling SN 1987A including the progenitor’s evolution, explosive nucleosynthesis, optical, X- and γ-ray light curves, and dust formation. The distribution of heavy elements in the ejecta is inferred from the light curves. The pre-peak optical light curve as well as early emergence of X- and γ-ray indicate the mixing of 56Ni into the hydrogen-rich envelope. The plateau-like peak of the optical light curve is well reproduced if hydrogen is mixed into the deep core. The flat X-ray light curve observed by Ginga would be due to the clumpy structure of the core. The progenitor’s blue-red-blue evolution and nitrogen abundance suggest that the progenitor’s hydrogen-rich envelope had mass M env = 7 − 11 M⊙ and was almost completely mixed.

Using the RHESSI satellite as a Compton polarimeter, a recent study claimed that the prompt emission of GRB021206 was almost fully linearly polarized. This was challenged by a subsequent reanalysis. We present an novel approach, applying our method to the same data. We identify Compton scattering candidates by carefully filtering events in energy, time, and scattering geometry. Our polarization search is based on time dependent scattering rates in perpendicular directions, thus optimally excluding systematic errors. We perform simulations to obtain the instrument's polarimetric sensitivity, and these simulations include photon polarization. For GRB021206, we formally find a linear polarization degree of Π GRB = (41 +57 −44)%, concluding that the data quality is insufficient to constrain the polarization degree in this case. We further applied our analysis to GRB030519B and found again a null result.

The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector operating at an altitude of ∼ 410 km aboard the International Space Station. The AMS silicon tracker, together with the permanent magnet, measures the rigidity (momentum/charge) of cosmic rays in the range from ∼ 0.5 GV to several TV. In order to have accurate rigidity measurements, the positions of more than 2000 tracker modules have to be determined at the micron level by an alignment procedure. The tracker was first aligned using the 400 GeV/c proton test beam at CERN and then realigned using cosmic-ray events after being launched into space. A unique method to align the permanent magnetic spectrometer for a space experiment is presented. The developed underlying mathematical algorithm is discussed in detail.

Evidence is presented from numerical magneto-hydrodynamical simulations for the existence of magnetic activity in late-type giant stars. A red supergiant with stellar parameters similar to that of Betelgeuse (α Orionis) is modeled as a "starin-a-box" with the high-order "Pencil Code". Both linear kinematic and non-linear saturated dynamo action are possible: the non-linear magnetic field saturates at a super-equipartition value corresponding to surface magnetic field of field strengths up to ∼500 Gauss. In the linear regime two different modes of dynamo action are found with exponential growth rates of ∼4 and 25 years, respectively. It is speculated that magnetic activity of late-type giants may influence dust and wind formation and possibly lead to the heating of the outer atmospheres of these stars.

This basic example is devoted to extending an existing catalogue with data taken elsewhere, either from CDS VizieR or Simbad database. We use the socalled "Spectroscopic Survey of Stars in the Solar Neighborhood" (aka. S 4 N, Allende Prieto et al. 2004; referenced as J / A + A / 4 2 0 / 1 8 3in VizieR) in order to retrieve all objects with available data for the main set of stellar parameters: effective temperature (Teff), surface gravity (logg) and metallicity ([Fe/H]). Then for each object in this dataset we query Simbad database to retrieve the projected rotational velocity (vsini). This combines Vizier and Simbad queries made using python's a s t r o q u e r ymodule. Compiling this collection of data is important for many problems in stellar astrophysics, such as the test of a stellar parameter inversion method. The tutorial covers remote database access, filtering tables with arbitrary criteria, creating and writing your own tables and basics of plotting in python.

Sun-like stars are able to continuously generate a large-scale magnetic field through the action of a dynamo. Various physical parameters of the star are able to affect the dynamo output, in particular the rotation and mass. Using new generation stellar spectropolarimeters (ESPaDOnS@CFHT, NARVAL@TBL), it is now possible to measure the large-scale magnetic field of solar analogues (i.e. stars very close to the Sun in the stellar-parameter plane, including strict solar twins). From spectropolarimetric time-series, tomographic inversion of polarized Zeeman signatures allows us to reconstruct the field geometry and its progressive distortion under the effect of surface differential rotation. We detail the first results obtained on a sample of four main-sequence dwarfs, with masses close to 1 solar mass and rotation rates between 1 and 3 solar rotation rate.

The solar radio burst type II on 4 th November 2015 was associated with minor CME that not lead towards the Earth. This clear type II burst recorded on spectrographs detected by the antenna in several locations (Gauri, Almaty, Kasi and Ooty) were obtained from CALLISTO website. The average time of the burst occurred are around 03:24 UT until 03:28 UT with the clear minor CME emerged recorded by SOHO at 03:12 UT. Although it just a minor CME but it is still giving the effect on Earth as it contributes to geomagnetic disturbance on the Earth during that day. The affected region reported by The Local news is Sweden, where the radar system for aviation was not clear, but it is back to normal after a few hours later. This geomagnetic disturbance is powerful enough that may cause the satellite damage, endanger astronauts and produce destructive surges on power grids.

Local interstellar spectra (LIS) of secondary cosmic-ray (CR) nuclei, lithium, beryllium, boron, and partially secondary nitrogen, are derived in the rigidity range from 10 MV to ∼200 TV using the most recent experimental results combined with state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. The lithium spectrum appears somewhat flatter at high energies compared to other secondary species, which may imply a primary lithium component. Two propagation packages, GALPROP and HELMOD, are combined to provide a single framework that is run to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. An iterative maximum-likelihood method is developed that uses GALPROP-predicted LIS as input to HELMOD, which provides the modulated spectra for specific time periods of the selected experiments for the model-data comparison. The proposed LIS accommodates the low-energy interstellar spectra measured by Voyager 1, the High Energy Astrophysics Observatory-3 (HEAO-3), and the Cosmic Ray Isotope Spectrometer on board of the Advanced Composition Explorer (ACE/CRIS), as well as the high-energy observations by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), Alpha Magnetic Spectrometer-02 (AMS-02), and earlier experiments that are made deep in the heliosphere. The interstellar and heliospheric propagation parameters derived in this study are consistent with our earlier results for propagation of CR protons, helium, carbon, oxygen, antiprotons, and electrons.

We calculate collision strengths and their thermally-averaged Maxwellian values for electron excitation and de-excitation between the fifteen lowest levels of singly-ionised cobalt, Co + , which give rise to emission lines in the near-and mid-infrared. Transition probabilities are also calculated and relative line intensities predicted for conditions typical of supernova ejecta. The diagnostic potential of the 10.52, 15.46 and 14.74 µm transition lines is briefly discussed.

From isobaric analog symmetry arguments and nuclear shell model calculations, we evaluate the temperature dependence of the beta-decay rates of the ground state and first excited state at an excitation energy of 96 keV in 19 O. It is shown that the decay from the excited level exceeds that of the ground state for T 9 1 1. This feature may be of significance in the r-process and explosive nucleosynthesis.

The study of stellar burning began just over 100 years ago. Nonetheless, we do not yet have a detailed picture of the nucleosynthesis within stars and how nucleosynthesis impacts stellar structure and the remnants of stellar evolution. Achieving this understanding will require precise direct measurements of the nuclear reactions involved. This report summarizes the status of direct measurements for stellar burning, focusing on developments of the last couple of decades, and offering a prospectus of near-future developments.

Using a new approach, we have obtained a formula for calculating the rotation period and radius of planets. In the ordinary gravitomagnetism the gravitational spin (S) orbit (L) coupling, L • S ∝ L 2 , while our model predicts that L • S ∝ m M L 2 , where M and m are the central and orbiting masses, respectively. Hence, planets during their evolution exchange L and S until they reach a final stability at which MS ∝ mL, or S ∝ m 2 v , where v is the orbital velocity of the planet. Rotational properties of our planetary system and exoplanets are in agreement with our predictions. The radius (R) and rotational period (D) of tidally locked planet at a distance a from its star, are related by, D 2 ∝ M m 3 R 3 and that R ∝ m M a.

Following our recent paper (Petrosian & Chen 2010), we have developed an inversion method to determine the basic characteristics of the particle acceleration mechanism directly and nonparametrically from observations under the leaky box framework. In the above paper, we demonstrated this method for obtaining the energy dependence of the escape time. Here, by converting the Fokker-Planck equation to its integral form, we derive the energy dependences of the energy diffusion coefficient and direct acceleration rate for stochastic acceleration in terms of the accelerated and escaping particle spectra. Combining the regularized inversion method of Piana et al. (2007) and our procedure, we relate the acceleration characteristics in solar flares directly to the count visibility data from RHESSI. We determine the timescales for electron escape, pitch angle scattering, energy diffusion, and direct acceleration at the loop top acceleration region for two intense solar flares based on the regularized electron flux spectral images. The X3.9 class event shows dramatically different energy dependences for the acceleration and scattering timescales, while the M2.1 class event shows a milder difference. The M2.1 class event could be consistent with the stochastic acceleration model with a very steep turbulence spectrum. A likely explanation of the X3.9 class event could be that the escape of electrons from the acceleration region is not governed by a random walk process, but instead is affected by magnetic mirroring, in which the scattering time is proportional to the escape time and has an energy dependence similar to the energy diffusion time.

We have observed the active star ξ Boo A (HD 131156A) with high precision broadband linear polarimetry contemporaneously with circular spectropolarimetry. We find both signals are modulated by the 6.43 d rotation period of ξ Boo A. The signals from the two techniques are 0.25 out of phase, consistent with the broadband linear polarization resulting from differential saturation of spectral lines in the global transverse magnetic field. The mean magnitude of the linear polarization signal is ∼4 ppm G-1 but its structure is complex and the amplitude of the variations suppressed relative to the longitudinal magnetic field. The result has important implications for current attempts to detect polarized light from hot Jupiters orbiting active stars in the combined light of the star and planet. In such work stellar activity will manifest as noise, both on the timescale of stellar rotation, and on longer timescales where changes in activity level will manifest as a baseline shift between observing runs.

Two close-in planets have been recently found around the M-dwarf flare star AU Microscopii (AU Mic). These Neptune-sized planets (AU Mic b and c) seem to be located very close to the so-called “evaporation valley” in the exoplanet population, making this system an important target for studying atmospheric loss on exoplanets. This process, while mainly driven by high-energy stellar radiation, will be strongly mediated by the space environment surrounding the planets. Here we present an investigation of this last area, performing 3D numerical modeling of the quiescent stellar wind from AU Mic, as well as time-dependent simulations describing the evolution of a highly energetic coronal mass ejection (CME) event in this system. Observational constraints on the stellar magnetic field and properties of the eruption are incorporated in our models. We carry out qualitative and quantitative characterizations of the stellar wind, the emerging CMEs, as well as the expected steady and transient...

We present the results of a massive variability search based on a photometric survey of a six square degree region along the Galactic plane at (l = 305 • , b = −0.8 •) and (l = 330 • , b = −2.5 •). This survey was performed in the framework of the EROS II (Expérience de Recherche d'Objets Sombres) microlensing program. The variable stars were found among 1 913 576 stars that were monitored between April and June 1998 in two passbands, with an average of 60 measurements. A new period-search technique is proposed which makes use of a statistical variable that characterizes the overall regularity of the flux versus phase diagram. This method is well suited when the photometric data are unevenly distributed in time, as is our case. 1362 objects whose luminosity varies were selected. Among them we identified 9 Cepheids, 19 RR Lyrae, 34 Miras, 176 eclipsing binaries and 266 Semi-Regular stars. Most of them are newly identified objects. The cross-identification with known catalogues has been performed. The mean distance of the RR Lyrae is estimated to be ∼4.9 ± 0.3 kpc undergoing an average absorption of ∼3.4 ± 0.2 mag. This distance is in good agreement with that of disc stars that contribute to the microlensing source star population. Our catalogue and light curves are available electronically from the CDS, Strasbourg and from our Web site * * .