Radio and visible light observations of matter ejected from the sun

1981 ◽  
Vol 244 ◽  
pp. L123 ◽  
Author(s):  
W. J. Wagner ◽  
E. Hildner ◽  
L. L. House ◽  
C. Sawyer ◽  
K. V. Sheridan ◽  
...  
Keyword(s):  
Visible Light ◽  
The Sun

Iron-catalyzed photoreduction of carbon dioxide to synthesis gas

2016 ◽  
Vol 6 (10) ◽  
pp. 3623-3630 ◽  
Author(s):  
Pamela G. Alsabeh ◽  
Alonso Rosas-Hernández ◽  
Enrico Barsch ◽  
Henrik Junge ◽  
Ralf Ludwig ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Visible Light ◽  
Synthesis Gas ◽  
Sustainable Energy ◽  
Photocatalytic Reduction ◽  
The Sun ◽  
Energy Applications ◽  
Iron Based ◽  
Photocatalytic Processes ◽  
Iron Based Catalysts

Photocatalytic processes to convert CO2 to useful products including CO and HCOOH are of particular interest as a means to harvest the power of the sun for sustainable energy applications. Herein, we report the photocatalytic reduction of CO2 using iron-based catalysts and visible light generating varying ratios of synthesis gas.

scholarly journals Transcript of final discussion session

2004 ◽  
Vol 359 (1448) ◽  
pp. 1323-1328 ◽  
Keyword(s):  
Visible Light ◽  
Imperial College ◽  
The Sun ◽  
Discussion Session ◽  
Surface Layers ◽  
The Earth ◽  
Dominant Part

A. Kornyshev ( Imperial College London, London, UK ). For life, we also need light, so we need surface. If you speak of the amount of other elements, they are in the Earth and we know that the dominant part of the surface is covered by water, and I think that water simply won the competition. There was so much water that life probably adjusted to the opportunity it had here, and when we are discussing, for example, what happens with our proteins when we put them into other solvents, they have not been trained to be there. So, it is an issue of competition, and the accessibility of the sun—and not only of the surface but also of surface layers, because of the transparency of water to visible light.

scholarly journals Correcting for Circumsolar and Near-Horizon Errors in Sky Cover Retrievals from Sky Images

2010 ◽  
Vol 4 (1) ◽  
pp. 45-52 ◽  
Author(s):  
C.N. Long
Keyword(s):  
Time Series ◽  
Statistical Analysis ◽  
Visible Light ◽  
Visual Inspection ◽  
Azimuth Angle ◽  
Forward Scattering ◽  
Frequency Of Occurrence ◽  
The Sun ◽  
Intensity Range ◽  
Sky Conditions

Fractional sky cover amounts retrieved from sky imagery are overestimated significantly at times due to occurrences of “whitening” near the sun, and near the horizon for low sun, in the images. This phenomenon occurs due to forward scattering of visible light by aerosols and haze, and the intensity range limitations of the detectors of the cameras used to record the sky images. Our results suggest that when the problem occurs, the magnitude of the overestimate is typically on the order of about 10% to 20% fractional sky cover. To help alleviate this problem, a statistical analysis of the time series of the areas in the image near the sun position and along the horizon centered on the solar azimuth angle has been developed. This statistical analysis requires that images be captured frequently, at least once per minute. For times when the overestimation is detected as occurring, a correction is applied to the retrieved sky cover amounts. When the sky cover amount correction is applied, analysis indicates that the result better matches the actual sky conditions present, as noted by visual inspection of the sky images in question. In addition, frequency-of-occurrence histogram comparisons show that the adjusted results improve the agreement with other methodologies and expectations. Thus, the methodology presented here helps produce more accurate fractional sky cover retrievals.

Make Hydrogen while the Sun Shines: The Photoelectrolysis of Water Using Oxide Semiconductors

2006 ◽  
Vol 45 ◽  
pp. 1902-1906
Author(s):  
Krishnan Rajeshwar ◽  
C. Raman Nair Chenthamarakshan ◽  
Norma R. de Tacconi ◽  
Sashikala Somasundaram
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Hydrogen Generation ◽  
Photoelectrochemical Cell ◽  
The Sun ◽  
Oxide Semiconductors ◽  
Solar Hydrogen ◽  
Cu2o Films ◽  
Inorganic Semiconductor ◽  
Semiconductor Photocatalyst

The principles of photoelectrochemical generation of hydrogen using inorganic semiconductor/water interfaces are first outlined. Advantages in the use of oxide semiconductors for solar hydrogen generation are then enumerated. The requirements for the water splitting reaction in terms of the semiconductor photocatalyst(s) are then elaborated. Finally, preliminary results are presented on the use of electrodeposited p-Cu2O films for hydrogen generation in a twin-compartment photoelectrochemical cell using visible light and sacrificial reducing agents in the (dark) anode compartment.

Chromospheric activity as a function of age in main-sequence stars

1966 ◽  
Vol 24 ◽  
pp. 40-43
Author(s):  
O. C. Wilson ◽  
A. Skumanich
Keyword(s):  
Main Sequence ◽  
The Sun ◽  
Main Sequence Stars ◽  
Tentative Conclusion ◽  
Chromospheric Activity ◽  
General Field ◽  
Large Clusters

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

A Search for Dyson Spheres around Late-Type Stars in the Solar Neighborhood II

1997 ◽  
Vol 161 ◽  
pp. 707-709 ◽  
Author(s):  
Jun Jugaku ◽  
Shiro Nishimura
Keyword(s):  
Solar Neighborhood ◽  
The Sun ◽  
Late Type ◽  
Solar Type

AbstractWe continued our search for partial (incomplete) Dyson spheres associated with 50 solar-type stars (spectral classes F, G, and K) within 25 pc of the Sun. No candidate objects were found.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

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