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Uranium-235 has a half-life of about 7.04 × 10 8 years; it is the next most stable uranium isotope after 238 U and is also predominantly an alpha emitter, decaying to thorium-231. [7] Uranium-235 is important for both nuclear reactors and nuclear weapons , because it is the only uranium isotope existing in nature on Earth in significant ...
List of orders of magnitude for areas 10 27 square metres and larger. Factor (m 2) Multiple Value Item 10 30: 1 square petametre (Pm 2) 10 31: 10 Pm 2: 10 32: 200 Pm 2: Roughly the surface area of an Oort Cloud: 300 Pm 2: Roughly the surface area of a Bok globule: 10 33: 1 000 Pm 2: 10 34: 30 000 Pm 2: Roughly the surface area of The Bubble ...
The sizes are listed in units of Jupiter radii (R J, 71 492 km).This list is designed to include all planets that are larger than 1.7 times the size of Jupiter.Some well-known planets that are smaller than 1.7 R J (19.055 R 🜨 or 121 536.4 km) have been included for the sake of comparison.
Chandra studies in the wavelength of the X-Rays show two ring-like structures of hot gas in M89's nucleus, suggesting an outburst there 1 to 2 million years ago [6] as well as ram-pressure stripping acting on the galaxy as it moves through Virgo's intracluster medium. [7] The supermassive black hole at the core has a mass of (4.8 ± 0.8) × 10 ...
As it is an opaque material, the remaining 10 percent must be reflected. Conversely, a low- e material such as aluminum foil has a thermal emissivity/absorptance value of 0.03 and as an opaque material, the thermal reflectance value must be 1.0 - 0.03 =0.97, meaning it reflects 97 percent of radiant thermal energy.
M. S. Bessell specified a set of filter transmissions for a flat response detector, thus quantifying the calculation of the color indices. [10] For precision, appropriate pairs of filters are chosen depending on the object's color temperature: B−V are for mid-range objects, U−V for hotter objects, and R−I for cool ones.
For measuring room temperature emissivities, the detectors must absorb thermal radiation completely at infrared wavelengths near 10×10 −6 metre. [15] Visible light has a wavelength range of about 0.4–0.7×10 −6 metre from violet to deep red. Emissivity measurements for many surfaces are compiled in many handbooks and texts.
The secondary component is a yellow main sequence star with an estimated stellar class of G5, 0.92 times the Sun's mass and 0.90 times the Sun's radius. The X-ray luminosity of this star is 6 × 10 28 erg s −1, which is 30 times greater than the peak activity level of the Sun. This higher activity level is expected for a young star of this class.