The Sun - Academia.edu (original) (raw)

Papers by The Sun

International Journal of Polymer Analysis and Characterization, 2014

ABSTRACT Bio-blend films were prepared with sago starch and N-vinyl-2-pyrrolidone (NVP) by the ca... more ABSTRACT Bio-blend films were prepared with sago starch and N-vinyl-2-pyrrolidone (NVP) by the casting method, varying the concentrations of sago starch (100 to 93%) and NVP (0 to 7%). The formulations were designated as F1 (starch 100%), F2 (starch 97%), F3 (starch 95%), and F4 (starch 97%). The highest tensile strength (TS), tensile modulus (TM), and elongation at break (Eb%) were found correspondingly to be 30.47 MPa, 407.74 MPa, and 8.25% for the F3 formulation. Gamma radiation was applied to films to modify their performance through grafting and cross-linking. The highest TS, TM, and Eb% were found at 500 krad dose and they were 38.12 MPa, 481.00 MPa, and 9.78%, respectively for F3 formulation. The water uptake nature and thermal properties of the treated and untreated films were also investigated.

The Astrophysical Journal, 1997

We have studied-ray line emission from fusion of accelerated-particles with ambient helium in 19 ... more We have studied-ray line emission from fusion of accelerated-particles with ambient helium in 19 solar ares observed by the Solar Maximum Mission Gamma Ray Spectrometer from 1980 to 1989. An isotropic or fan beam distribution of accelerated particles provides good ts to the line pro les for most of the ares. In contrast, a downward beam of accelerated particles can be ruled out at high con dence, 99.99% and 99.8%, for the two most intense ares and provides signi cantly poorer ts than isotropic or fan-beam distributions in two other ares. The uences in the-lines, with a few exceptions, show a correlation with uences of the narrow nuclear de-excitation lines from elements with high rst ionization potential. If we assume that all accelerated ions have the same spectral shape, and if we adopt accelerated particle and ambient abundances derived from other-ray line studies, we nd that an accelerated /proton ratio of 0.5 is consistent with the spectra from the 19 ares, whereas a ratio of 0.1 is not. We also suggest the possibility that 7 Be produced in-4 He fusion during the intense ares occurring in late 1989 may have reached Earth in high enough concentration to account, in part, for 7 Be observed in NASA's LDEF satellite after its recovery in early 1990.

Eta Carinae and …, 2001

... 2J~, 2001 T. Gull, S. Johansson ~4 K. Davidson Cool Star Chromospheres and the Sun Jeffrey Li... more ... 2J~, 2001 T. Gull, S. Johansson ~4 K. Davidson Cool Star Chromospheres and the Sun Jeffrey Linsky and Seth Redfield JILA, University of Colorado and NIST, Boulder, CO 80309-0440 Tom Ayres, Alex Brown, and Graham Harper CASA, University of Colorado, Boulder, CO ...

Astronomy & Astrophysics, 2001

Acoustic power and oscillation amplitudes of radial oscillations computed for a solar model are c... more Acoustic power and oscillation amplitudes of radial oscillations computed for a solar model are compared with solar seismic observations. The oscillations are assumed to be stochastically excited by turbulence. The numerical computations are based upon a theoretical formulation of the power going into solar-like oscillation modes, as proposed by Samadi & Goupil (2001) in a companion paper. This formulation allows us to investigate several assumptions concerning properties of the stellar turbulence. We find that the entropy source plays a dominant role in the stochastic excitation compared with the Reynold stress source, in agreement with Goldreich et al. (1994). We consider several turbulent kinetic energy spectra suggested by different observations of the solar granulation. Differences between turbulent spectra manifest in large differences in the computed oscillation powers at high oscillation frequency. Two free parameters which are introduced in the description of the turbulence enter the expression for the acoustic power. These parameters are adjusted in order to fit to the solar observations of the surface velocity oscillations. The best fit is obtained with the kinetic energy spectrum deduced from the observations of the solar granulation by Nesis et al. (1993); the corresponding adjusted parameters are found to be compatible with the theoretical upper limit which can be set on these parameters. The adopted theoretical approach improves the agreement between solar seismic observations and numerical results.

Universiti Malaya, Universiti Kebangsaan Malaysia, Universiti Sains Malaysia and universiti Putra... more Universiti Malaya, Universiti Kebangsaan Malaysia, Universiti Sains Malaysia and universiti Putra Malaysia have retained their status as research universities for another three years begining this year, Higher Education Minister Datuk Seri Mohamed Khalid Nordin said yesterday

International Journal of Polymer Analysis and Characterization, 2014

ABSTRACT Bio-blend films were prepared with sago starch and N-vinyl-2-pyrrolidone (NVP) by the ca... more ABSTRACT Bio-blend films were prepared with sago starch and N-vinyl-2-pyrrolidone (NVP) by the casting method, varying the concentrations of sago starch (100 to 93%) and NVP (0 to 7%). The formulations were designated as F1 (starch 100%), F2 (starch 97%), F3 (starch 95%), and F4 (starch 97%). The highest tensile strength (TS), tensile modulus (TM), and elongation at break (Eb%) were found correspondingly to be 30.47 MPa, 407.74 MPa, and 8.25% for the F3 formulation. Gamma radiation was applied to films to modify their performance through grafting and cross-linking. The highest TS, TM, and Eb% were found at 500 krad dose and they were 38.12 MPa, 481.00 MPa, and 9.78%, respectively for F3 formulation. The water uptake nature and thermal properties of the treated and untreated films were also investigated.

The Astrophysical Journal, 1997

We have studied-ray line emission from fusion of accelerated-particles with ambient helium in 19 ... more We have studied-ray line emission from fusion of accelerated-particles with ambient helium in 19 solar ares observed by the Solar Maximum Mission Gamma Ray Spectrometer from 1980 to 1989. An isotropic or fan beam distribution of accelerated particles provides good ts to the line pro les for most of the ares. In contrast, a downward beam of accelerated particles can be ruled out at high con dence, 99.99% and 99.8%, for the two most intense ares and provides signi cantly poorer ts than isotropic or fan-beam distributions in two other ares. The uences in the-lines, with a few exceptions, show a correlation with uences of the narrow nuclear de-excitation lines from elements with high rst ionization potential. If we assume that all accelerated ions have the same spectral shape, and if we adopt accelerated particle and ambient abundances derived from other-ray line studies, we nd that an accelerated /proton ratio of 0.5 is consistent with the spectra from the 19 ares, whereas a ratio of 0.1 is not. We also suggest the possibility that 7 Be produced in-4 He fusion during the intense ares occurring in late 1989 may have reached Earth in high enough concentration to account, in part, for 7 Be observed in NASA's LDEF satellite after its recovery in early 1990.

Eta Carinae and …, 2001

... 2J~, 2001 T. Gull, S. Johansson ~4 K. Davidson Cool Star Chromospheres and the Sun Jeffrey Li... more ... 2J~, 2001 T. Gull, S. Johansson ~4 K. Davidson Cool Star Chromospheres and the Sun Jeffrey Linsky and Seth Redfield JILA, University of Colorado and NIST, Boulder, CO 80309-0440 Tom Ayres, Alex Brown, and Graham Harper CASA, University of Colorado, Boulder, CO ...

Astronomy & Astrophysics, 2001

Acoustic power and oscillation amplitudes of radial oscillations computed for a solar model are c... more Acoustic power and oscillation amplitudes of radial oscillations computed for a solar model are compared with solar seismic observations. The oscillations are assumed to be stochastically excited by turbulence. The numerical computations are based upon a theoretical formulation of the power going into solar-like oscillation modes, as proposed by Samadi & Goupil (2001) in a companion paper. This formulation allows us to investigate several assumptions concerning properties of the stellar turbulence. We find that the entropy source plays a dominant role in the stochastic excitation compared with the Reynold stress source, in agreement with Goldreich et al. (1994). We consider several turbulent kinetic energy spectra suggested by different observations of the solar granulation. Differences between turbulent spectra manifest in large differences in the computed oscillation powers at high oscillation frequency. Two free parameters which are introduced in the description of the turbulence enter the expression for the acoustic power. These parameters are adjusted in order to fit to the solar observations of the surface velocity oscillations. The best fit is obtained with the kinetic energy spectrum deduced from the observations of the solar granulation by Nesis et al. (1993); the corresponding adjusted parameters are found to be compatible with the theoretical upper limit which can be set on these parameters. The adopted theoretical approach improves the agreement between solar seismic observations and numerical results.

Universiti Malaya, Universiti Kebangsaan Malaysia, Universiti Sains Malaysia and universiti Putra... more Universiti Malaya, Universiti Kebangsaan Malaysia, Universiti Sains Malaysia and universiti Putra Malaysia have retained their status as research universities for another three years begining this year, Higher Education Minister Datuk Seri Mohamed Khalid Nordin said yesterday