| Exoplanetary Scratchpad|
Nearest Types of Systems Web PagesEdit
Nearest Types of Systems In the NewsEdit
Nearest Systems by TypeEdit
- Alpha Centauri System (4.3 ly) - Nearest Star System, Nearest Multiple Star System, Nearest Triple Star System, Nearest Binary Star System Nearest Red Dwarf Star, Nearest Flare Star, Nearest Yellow Dwarf Star, Nearest Orange Dwarf Star, Nearest Confirmed Planet, Nearest Terrestrial Planet, Nearest Hot Terrestrial Planet, Nearest Planet detected with dopplar spectrometry - Alpha Centauri is also known as Rigil Kentaurus. A is also known as HD 128620 and HR 5459, B is HD 128621 and HR 5460, and C is Proxima Centauri. It is the nearest star system to the Sun. Contains a yellow dwarf star a little bigger than the Sun and an orange star a little smaller orbiting each other orbiting each other about the distance Uranus is from the Sun (varies from Saturn like to Neptune like), as well as a distant Red Dwarf companion Proxima that may or may not be orbiting the other two.
Stellar fingerprinting suggests a high probability that a planet orbits star A, due to dearth of Iron around star. Russian astronomers announced the detection of a second planet orbiting the binary pair at 80 AU with a 100 year period, which appears to be false. The stars in the system will become markedly closer together in 2016, making observations much more difficult and one follow up failed to find it. The system is the first target for the European Cheops exoplanet space telescope.
First planet discovered is an Earth-massed rocky-iron planet with no atmosphere at epistellar distances around the orange dwarf star B found by HARPS. This is the least massive planet found around a sunlike star. The planet was informally and controversially named by Uwingu during a fund raising naming contest Albertus Alauda, after a participant's grandfather. Earthlike planets are not detectable in the habitable zone with present radial velocity methods. Technique for detection of planet is a source of doubt for some and it has yet to be independently verified. A team thought they might have detected a transit of this planet, but further observations showed the timing wasn't consistent. It is possible that a second further out (20.4 day period) Earth-sized planet is altering the transit times of the first. A cheap crowdfunded satellite devoted to studying this star could confirm the planets. The star was observed to be a good candidate to host a "super Habitable" planet, which would have 25% more gravity than the Earth, shallow seas, flatter landscape, higher atmospheric pressure, and the 6 BYO star would be stable for life longer.
Proxima, a small flare star, was discovered in 1915 by Robert Ines, who named it. Long suspected planet around Proxima found not to exist. The Pale Red Dot project is dedicated to finding a planet around Proxima using dopplar spectrometry. As Proxima passes in front of two stars (once in 2014, again in 2016), any planets within 5 AU should be detectable via microlensing using the HST. It is known that no planets of Neptune sized mass exist within 1 AU and no Jovians with periods up to 1000 days, or transiting planets exist. An Earth-like planet in the habitable zone was discovered around Proxima Centauri. In 2017, a large stellar flare erupted and bombarded the planet, making it likely that the atmosphere has been completely stripped away by events such as this and not a good candidate for life. It was thought that a lot of dust existed in the system, making it feasable that the star had a rich complement of planets, but this seems to not be the case.
- Barnard's Star System (6.0 ly) - Nearest single red dwarf star, nearest without known planets, nearest inactive red dwarf, nearest very old star, nearest Population II star, nearest star not visible to the naked eye - Barnard's Star is also known as Gliese 699 and informally as Proxima Ophiuchi. Named for the astronomer E. E. Barnard, who discovered it in 1916 and was the first to measure its proper motion. Second closest star system to the Sun and the one with the highest proper motion in the sky - due to its rapid approach to the Sun. Will get as close as 3.8 ly away in 12,000 years. A red dwarf thought early on to have a planet around it found due to radial velocity method, which has been disproved. A super earth has been detected at Mercury-like distances, but beyond the frost line. Life could be possible if an additional source of heat was provided. A potential target for the 1970's Project Daedelus. The star is very ancient 11-12 Billion Years Old, and is the nearest inactive Red Dwarf Star. It may take another 40 Billion Years before it cools to become a Black Dwarf. Astronomers were surprised to discover that it was a flare star in 2003, and dubbed it V2500 Ophiuchi.
- Lalande 21185 System (8.3 ly) - Nearest galactic "Thick Disk" star - Lalande 21185 is also called GJ 411 and informally Proxima Ursa Majoris. It is the fourth closest star system to the Sun at 8.3 ly. It is the third brightest red dwarf in the night sky. It has been the spectral standard star for class M2 V for a long time. It is sometimes classified as a BY Draconis type variable star and has been known to emit x-rays. Van de Kamp thought he found planets in 1951. The system has two unconfirmed planets detected via radial velocity in 1996. It is also one of the earliest planets detected that still has a good chance to exist. The planets orbit far away from their dim Red Dwarf star, which makes one planet colder than Saturn and the other colder than Neptune despite being at a Saturn-like distance. One confirmed planet is a hot super earth with a rocky surface. The star is the nearest Galactic 'Thick Disk' star (which includes about 4% of nearby stars), and moves perpendicular to the galactic plane. It will get nearest to the Sun in 19,000 years when it is 4.65 ly.
- Sirius System (8.6 ly) - Nearest white dwarf star, nearest star in a hotter class than the Sun, nearest blue-white A dwarf star, nearest system with dust detected. - Sirius is also known as Alpha Canis Majoris and Gliese 244. The brightest star in the sky. A hot blue-white main sequence star with a white dwarf (the "pup") orbiting it. Orbit distance varies between 8.1 and 31.5 ly and takes 50 years to navigate. The habitable zone of Star A is centered 4.25 AU from the star and may be disrupted due to the presence of Star B. Long thought to be a part of the Ursa Major Moving Group (also called the "Sirius Group"), it was found to be too young to be a member and not heading in the right direction. The brightest star within a large distance from the Sun. Star B is about the same mass as the Sun, but is almost the same size as the Earth. It may have evolved from a 5 solar massed B-type main sequence star. It is the nearest and first discovered white dwarf star. Dust has been detected from the system, probably from material sluffed off from Star B. A search in 2008 using high contrast imaging for planets within 10 Jupiter masses within 25 AU of the binary star turned up negative.
- Epsilon Eridani System (10.5 ly) - Nearest solitary orange dwarf, Nearest Jovian, Nearest Eccentric Jupiter, Nearest dust disk, Nearest asteroid belt, nearest Kuiper belt - Ran (Epsilon Eridani) is the nearest single non-red dwarf star to the Sun, also known as HD 195019, Gl 144, and HR 1084. It is a member of the Ursa Major star association and close encounters to other stars is relatively common. One of the first stars found to have a dust disk, with several potential planets suspected in the gaps early on, and later on of the earliest nearest system with confirmed planets. Has an inner asteroid belt at 3 AU, Jovian planet AEger at 3.4 AU, outer asteroid belt at 20 AU, and Kuiper Belt at 35-100 AU. A planet is proposed to be just outside the outer asteroid belt, and another just before the Kuiper belt.Because the star is very chromospherically active, doubts were cast on planet's b's existence. Hubble then confirmed its existence with astrometrics and found to be orbiting in the plane of the dust disks, which supported the theory that planets are born from dust disks and yielded a precise mass of 1.5 MJ. The planet b was originally thought to be extremely eccentric (2-10 AU), but later discovery of the inner asteroid belt suggests it is more moderately eccentric so as not to cross the belt. It could still have high eccentricity if the outer belt was being fed with material from the outer belt though. Dinosaur-killing sized impacts would be frequent on any Earth-like planets, about once every 2 million years. One of 5 PICTURE-C targets selected for sub-orbital coronograph observation. One of the first 20 exoplanet systems allowed to be given common names by the IAU. Star is named after a Norse goddess of the seas, while the planet after her husband, god of the ocean. A common sci fi system, including the original home of Star Trek Vulcans (though this moved to 40 Eridani) and Babylon 5.
- Procyon System (11.4 ly) - Nearest Yellow-White G Dwarf Star - Procyon is also known as Alpha Canis Minoris, HD 61421, and HR 2943. Nearby Bright star system. Nearest yellow white star (F5 IV–V) to the Sun and the closest star to Sirius. It is the 7th brightest star in the sky. Has a white dwarf companion B. Has about 50% more mass than the Sun and about twice its radius. It is a BY-Draconis type of variable (unusual for a bright star) and entering the last stage of its life on the main sequence, heading towards a sub-giant, as its core seems to have exhausted its supply of Hydrogen and is starting to fuse Helium. Its habitable zone, which is 2 to 4 AU, may be disrupted by B, which is only 9 to 21 AU away. Star B was first predicted due to its effect on A's proper motion in 1844 and later spotted in 1896. It was probably about the same mass as Star A, and sterilized the system when it went into a giant phase. Luyten's Star is only 1.2 light years away, near enough to stir up any Oort clouds in either system and would be dimly visible.
- Epsilon Indi System (11.8 ly) - Nearest Brown Dwarf - Epsilon Indi is the also known as HR 8387, Gl 845, and HD 209100. Second nearest single sunlike star to the Sun. Orange dwarf with a binary brown dwarf orbiting it. The smaller of the two is the closest thing to an "extrasolar moon" found so far. The constellation "Indus" first appeared in 1603 in the Uranometria. Epsilon Indi appeared as one of the Indian's arrows in Bode's 1801 atlas, the Uranographia. The star's high proper motion was first discovered by Gill in 1882, which was improved upon by Shapley in 1923. During 1960, the star was observed for radio signals, but none was found. In 1972, it was searched for ultraviolet laser signals. It leads a Carnegie list of stars most likely to have an earth-like planet. The star's age has been controversial, at first thought to be older than the sun, then younger, then even older than originally thought, all based on studies regarding the brown dwarf's nature and the rotation rate of the star.
- Tau Ceti System (11.9 ly) - Nearest Single Yellow Dwarf Star - Tau Ceti is also known as HD 10700, HR 509, and Gl 71. The nearest single G-class yellow dwarf to the sun, somewhat smaller than the Sun. A popular science fiction subject and one of two targets of SETI-forerunner Project Ozma in the 1960s. Despite being somewhat older than the sun, it has an extensive asteroid and/or comet field 10-50 AU, with the bulk between 35 and 50 AU. It has about ten times as much material as the Sun. This would make life difficult. It is a metal deficient star, so it is thought less likely to host rocky planets. Traditional dopplar spectrometry has ruled out any large Jupiter sized planets at Jupiter like distances or closer in, which was thought to be good for any potentially habitable planets. Five candidate rocky super Earth planets were detected though using a new method of planetary detection. This method made predictions of the stellar "noise" activity that might obscure detection of a planet based on the long history of dopplar measurements done on this system. Deviations from this prediction pointed towards the existence of planets. Confirmation using more established methods is needed. These planets are labeled b through f as you go outward, span 0.1 AU to 1.35 AU, and get larger the further you go out (at least 2 ME to 6.6 ME). The outermost two are near the habitable zone and were originally hailed as possibly being the nearest and smallest known habitable planets. More recent modeling indicates they are not actually habitable though. Planet e is probably too close to the star and only in the HZ if generous assumptions are made. Planet f has probably only been in the habitable zone for about a billion years as a result of its star becoming hotter, which might make biosigns difficult to detect from Earth, considering it took 2 BY for biosigns to become detectable around the Earth. Since the star has a higher magnesium to silicon ratio than the Sun, these planets compositions could be quite different that the Solar System's. The lower mantles could be dominated with ferropericlase, which is not very viscious, which may make the rocks of the mantle flow easier than on Earth, affecting volcanism and tectonics. One of 5 PICTURE-C targets selected for sub-orbital coronograph observation.
- UGPS 0722-05 System (13 ly) - Nearest single Brown Dwarf - The nearest known solitary brown dwarf.
- Van Maanen's Star System (14.4 ly) - Nearest single White Dwarf - Van Maanen's star is also called Gl 35 and informally Proxima Piscium. The nearest single White Dwarf star, the third discovered, and the first solitary white dwarf discovered. Has more neighboring stars within 10 ly than any other star within 20 ly of the Sun, but none of them is as close as the Alpha Centauri is from the Sun. Several inconsistent studies suggest planets, but none confirmed. A plate from 1917 was discovered that showed evidence of a consumed planet in the star, the earliest evidence for an exoplanet.