|
Hot Neptunes
A hot Neptune is a type of giant planet with a mass similar to that of Neptune or Uranus orbiting close to its star, normally within less than 1 AU. The first hot Neptune to be discovered with certainty was Gliese 436 b (Awohali) in 2007, an exoplanet about 33 light years away. Recent observations have revealed a larger potential population of hot Neptunes in the Milky Way than was previously thought. Hot Neptunes may have formed either ''in situ'' or ''ex situ''. General characteristics Because of their close proximity to their parent stars, hot Neptunes have a much greater rate and chance of transiting their star as seen from a farther outlying point, than planets of the same mass in larger orbits. This increases the chances of discovering them by transit-based observation methods. Transiting hot Neptunes include Gliese 436 b (Awohali) and HAT-P-11b. Gliese 436 b was the first hot Neptune to be discovered with certainty in 2007. The exoplanet Mu Arae c (Dulcinea) discove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methods Of Detecting Exoplanets
Methods of detecting exoplanets usually rely on indirect strategies – that is, they do not directly Astrophotography, image the planet but deduce its existence from another signal. Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty of detecting such a faint light source, the Glare (vision), glare from the parent star washes it out. For those reasons, very few of the exoplanets reported have been detected directly, with even fewer being resolved from their host star. Established detection methods The following methods have proven successful at least once for discovering a new planet or detecting an already discovered planet: Radial velocity A star with a planet will move in its own small orbit in response to the planet's gravity. This leads to variations in the speed with which the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Zero Foundation
The Breakthrough Propulsion Physics Project (BPP) was a research project funded by NASA from 1996 to 2002 to study various proposals for revolutionary methods of spacecraft propulsion that would require breakthroughs in physics before they could be realized. The project ended in 2002, when the Advanced Space Transportation Program was reorganized and all speculative research (less than Technology readiness level 3) was cancelled. During its six years of operational funding, this program received a total investment of $1.2 million. The Breakthrough Propulsion Physics project addressed a selection of "incremental and affordable" research questions towards the overall goal of propellantless propulsion, hyperfast travel, and breakthrough propulsion methods. It selected and funded five external projects, two in-house tasks and one minor grant. At the end of the project, conclusions into fourteen topics, including these funded projects, were summarized by program manager Marc G. Millis. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vega
Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, and one of the most luminous stars in the Sun's neighborhood. It is the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus. Vega has been extensively studied by astronomers, leading it to be termed "arguably the next most important star in the sky after the Sun". Vega was the northern pole star around 12,000 BCE and will be so again around the year 13,727, when its declination will be . Vega was the first star other than the Sun to have its image and spectrum photographed. It was one of the first stars whose distance was estimated through parallax measurements. Vega has functioned as the baseline for calibrating the photometric brightness scale and was one of the stars ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LTT 9779 B
LTT 9779 b, officially named Cuancoá, is a Neptune-sized planet orbiting the sunlike star LTT 9779, or Uúba. As of 2023, it has the highest-known albedo of any planet. It was discovered in 2020 using data from the Transiting Exoplanet Survey Satellite (TESS), and is also called TOI-193 b. Characteristics LTT 9779 b is one of the few known planets in the Neptunian desert. It is highly reflective, with an albedo of . This makes it the most reflective exoplanet discovered so far. It completes an orbit around LTT 9779 in less than a day, making temperatures on the day side soar to over 2,000 degrees Celsius. Global climate models of the planet indicate it has a very metal-rich atmosphere, with clouds made of silicate likely being present. Being in the Neptunian desert, LTT 9779 b is a very rare class of planet, with few like it being known. It is estimated that only 1 in 200 Sun-like stars possess a planet with an orbital period of less than a day, and most of those are Hot J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refractory Materials
In materials science, a refractory (or refractory material) is a material that is resistant to Thermal decomposition, decomposition by heat or chemical attack and that retains its strength and rigidity at high temperatures. They are Inorganic compound, inorganic, Nonmetal, non-metallic compounds that may be Porosity, porous or non-porous, and their crystallinity varies widely: they may be Crystal, crystalline, polycrystalline, Amorphous solid, amorphous, or Composite material, composite. They are typically composed of oxides, carbides or nitrides of the following elements: silicon, aluminium, magnesium, calcium, boron, chromium and zirconium. Many refractories are ceramics, but some such as graphite are not, and some ceramics such as clay pottery are not considered refractory. Refractories are distinguished from the ''refractory metals'', which are elemental metals and their alloys that have high melting temperatures. Refractories are defined by ASTM International, ASTM C71 as " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amorphous Ice
Variations in pressure and temperature give rise to different phases of ice, which have varying properties and molecular geometries. Currently, twenty-one phases, including both crystalline and amorphous ices have been observed. In modern history, phases have been discovered through scientific research with various techniques including pressurization, force application, nucleation agents, and others. On Earth, most ice is found in the hexagonal Ice Ih phase. Less common phases may be found in the atmosphere and underground due to more extreme pressures and temperatures. Some phases are manufactured by humans for nano scale uses due to their properties. In space, amorphous ice is the most common form as confirmed by observation. Thus, it is theorized to be the most common phase in the universe. Various other phases could be found naturally in astronomical objects. Theory Most liquids under increased pressure freeze at ''higher'' temperatures because the pressure helps to hold ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volatile (astrogeology)
Volatiles are the group of chemical elements and chemical compounds that can be readily vaporized. In contrast with volatiles, elements and compounds that are not readily vaporized are known as refractory substances. On planet Earth, the term 'volatiles' often refers to the volatile components of magma. In astrogeology volatiles are investigated in the crust or atmosphere of a planet or moon. Volatiles include nitrogen, carbon dioxide, ammonia, hydrogen, methane, sulfur dioxide, water and others. Planetary science Planetary scientists often classify volatiles with exceptionally low melting points, such as hydrogen and helium, as gases, whereas those volatiles with melting points above about 100 K (–173 °C, –280 °F) are referred to as ices. The terms "gas" and "ice" in this context can apply to compounds that may be solids, liquids or gases. Thus, Jupiter and Saturn are gas giants, and Uranus and Neptune are ice giants, even though the vast majority of the "gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury (planet)
Mercury is the first planet from the Sun. It is a rocky planet with a trace atmosphere. While it is the List of Solar System objects by size, smallest and least massive planet of the Solar System, its surface gravity is slightly higher than that of Mars. The surface of Mercury is similar to Earth's Moon, heavily Impact crater, cratered, with expansive rupes system, generated from thrust faults, and bright ray systems, formed by ejecta. Its largest crater, Caloris Planitia, has a diameter of , which is about one-third the diameter of the planet (). Being the most inferior planet, inferior orbiting planet it appears in Earth's sky, always close to the Sun, either as a "morning star" or an "evening star". It stays most of the time the closest to all other planets and is the planet with the highest delta-v needed to travel to from all other planets of the Solar System. Mercury's sidereal year (88.0 Earth days) and sidereal day (58.65 Earth days) are in a 3:2 ratio. This relation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kepler-56b
Kepler-56b (KOI-1241.02) is a hot Neptune—a class of exoplanets—located roughly away. It is somewhat larger than Neptune and orbits its parent star Kepler-56 and was discovered in 2013 by the Kepler Space Telescope. Planetary orbit Kepler-56b is about away from its host star (about one-tenth of the distance between Earth to the Sun), making it even closer to its parent star than Mercury () and Venus (). It takes 10.5 days for Kepler-56b to complete a full orbit around its star. Further research shows that Kepler-56b's orbit is about 45° misaligned to the host star's equator. Later radial velocity measurements have revealed evidence of a gravitational perturbation from Kepler-56d. Both Kepler-56b and Kepler-56c will be devoured by their parent star in about 130 and 155 million years. Even further research shows that it will have its atmosphere boiled away by intense heat from the star, and it will be stretched by the strengthening stellar tides. The measured m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
