Sunday, September 30, 2007

DO255-470

Star type
g White dwarf

Distance from Earth
g 20.49 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA

Brightness (xSol)
g NA

Metallicity
g NA

Comparison to Sol
g See chart

Picture of star
g NA

Star system features
g NA

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g NA

Other names
g NA

Sci-fi mentions
g NA

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Saturday, September 29, 2007

Gliese 581

Star type
g M2.5 V

Distance from Earth
g 20.45 ly

Star Service No.
g NA

Age
g At least two billion years old, possibly around 4.3 billion years old ; as brightness does not vary much, star is probably several billion years old

Radius/Mass/Temp (xSol)
g 38%; 31.5%; 3,480 K

Brightness (xSol)
g 1.3%

Metallicity
g Between 36 to 62 percent as enriched as Sol in elements heavier than hydrogen

Comparison to Sol
g See chart (similar to Proxima)

Picture of star
g See picture above right
g Artist's conceptions of star with its planets

Star system features
g  Hosts vast amounts of cometary debris, at least 10 times more comets than in our own Solar System's Kuiper Belt, possibly because it hosts no Saturn-Jupiter-sized planets

Known planets
g Gliese 581 b: ; mass is 4.9% of Jupiter or 1560% of Earth; orbits in 5.4 days at distance of 0.041 AU
g Gliese 581 c: First low mass extrasolar planet found to be in its star's habitable zone, the more Earth-like planet has at least 5.03 Earth-masses (or 0.0158 Jupiter-masses) and an estimated diameter of at least 1.5 times Earth's if it is rocky, larger if it is composed of mostly ice. It moves around Gliese 581, outside of planet b's orbit, at an average distance of 0.073 AU, in a circular orbit (e=0.28 ± 0.06) which it completes in 12.932 (± 0.007) days. Initially thought to be located within the so-called habitable zone of Gliese 581, “c” almost certainly have a runaway greenhouse effect (surface temperatures of about 500 degress Celsius), and would not be habitable. Some believe the system may have undergone planetary migration and Gliese 581 c may have formed beyond the frost line, with a composition similar to icy bodies like Ganymede. The star would appear to be five times larger in the sky of "c" than the sun does in Earth's sky. Though only 7% as far from its star as Earth is from the Sun, Gliese 581 illuminates this planet about 40% that of the Sun does to the Earth. Intensity of UV, visible and IR radiation would be about 265% as intense as the Sun is to Earth; if ratio of outgoing radiation emissivity to incoming radiation absorption is the sameas Earth's, then average planet surface temperature for "c" would be 95 C. Also see: Speculation about geology/geochemistry of Gliese 581c; comparison to earth illustration.
g Gliese 581 d: Near the outer edge of the habitable zone; “d’ is at least 7.7 Earth-masses (or 0.0243 Jupiter-masses). It revolves around Gliese 581 - outside of planet b's orbit - at an average distance of 0.25 AU, in a roughly circular orbit (e= 0.2 ± 0.09) which it completes in 83.6 (± 0.7) days, not quite a quarter of an Earth year. Although it is possible that this detection is actually caused by a large star spot, the discoverers believe that the host star is too inactive for this possibility to be likely. At first glance, Gliese 581d is a pretty poor candidate in the hunt for life: it receives less than a third of the stellar energy Earth does and may be tidally locked, with a permanent day and night side, meaning the atmosphere would freeze out. New calculations suggests that a greenhouse effect under the right atmospheric conditions may make it possible for liquid water to persist on its surface. With a dense carbon dioxide atmosphere - a likely scenario on such a large planet - the climate is not only stable against collapse, but warm enough to have oceans, clouds and rainfall. The denser air and thick clouds would keep the surface in a perpetual murky red twilight, and its large mass means that surface gravity would be around double that on Earth. Also see: Gliese 581d: A Habitable Exoplanet?
g Gliese 581g, or Zarmina's World: Originally this planet was thought to have a mass similar to that of Earth and was close to the center of the habitable zone. For several months, the discovery of the first potential Earth twin outside the Solar System seemed to have been achieved. Unfortunately, later analysis by independent teams has raised serious doubts on this extremely difficult detection. Many now believe that Gliese 581g may not exist at all. Instead, it may simply be a result of noise in the ultra-fine measurements of stellar wobble needed to detect exoplanets in this system.

Habitable zone
g Around 0.11 and 2.8 AUs; in sky of planet, bloated red sun is 10x Sun

Orbital map
g See animation
g No Jupiter-mass planet orbits Gliese 581 with a period of around 10 years or less; star's low metallicity suggests a Jupiter-mass planet could not form around star

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g HN Librae: 4.3 ly
g Gliese 570 ABCD: 5.2 ly
g LP 914-54: 6.8 ly
g Gliese 570 ABCD: 6.9 ly
g L 768-11: 8.2 ly
g Wolf 630 ABC: 8.2 ly
g Hip 72509: 8.2 ly
g BD-12 4523 AB: 8.4 ly
g Wolf 629 AB: 8.6 ly
g CD-25 10553 AB: 8.7 ly

Map locating star system
g See stellar map

Location in Earth sky
g Northeast part of Constellation Libra, the Scales - northeast of Delta Librae, north of Gamma Librae and Graffias (Beta Scorpii), and southwest of Epsilon (Yed Posterior) and Delta (Yed Prior) Ophiuchi, and Mu, Epsilon, and Alpha (Unukalhai) Serpentis

Other names
g HO Librae, Wolf 562, CD-45 13677, BD-07 4003, LHS 394, NSV 7023, Hip 74995, G 151-46, G 152-9, LTT 6112, LPM 564, LFT 1195, Vys/MCC 159

Sci-fi mentions
g A wormhole starting at Neptune opens at Wolf 562 in Geoffrey Landis' short story "Approaching Perimelasma"

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Friday, September 28, 2007

EQ Pegasi ABCD

Star type
g A: M3.5
g B: M4.5
g C: NA
g D: NA

Distance from Earth
g 20.38 ly

Star Service No.
g NA

Age
g A: NA
g B: NA

Diameter/Mass/Temp (xSol)
g A: NA; 23%; NA
g B: NA; 10.9%; NA

Brightness (xSol)
g A: 0.2737%
g B: 0.0434%

Metallicity
g A: NA
g B: NA

Comparison to Sol
g A/B: See chart (similar to Proxima)
g C:
g D:

Picture of star
g NA

Star system features
g NA

Known planets
g Claim that SETI during late 1990s received signal from binary has proven to be hoax

Habitable zone
g NA

Orbital map
g NA

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g See stellar map

Location in Earth sky
g In constellation Pegasus

Other names
g A: NS 2331+1956 A
g A-D: GJ 896 ABCD
g G 068-024
g HIP 116132
g BD+19 5116
g A: LHS 3965
g B: LHS 3966

Sci-fi mentions
g NA

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Thursday, September 27, 2007

LHS 3003

Star type
g M7.0

Distance from Earth
g 20.26 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA; 3.1%; NA

Brightness (xSol)
g 0.0005%

Metallicity
g NA

Comparison to Sol
g 0.0051%

Picture of star
g NA

Star system features
g Star is discussed in research paper "CCD Parallaxes for Southern Very Low Luminosity Stars"

Known planets
g NA

Habitable zone
g 0.0023 A.U.s

Orbital map
g NA

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g Gliese 570: 2.47987 ly (K5e V)
g Cordoba Durchmusterung -40°9712: 5.40908 ly
g Bonner Durchmusterung -11°3759: 5.63304 ly
g Gliese 581: 7.46322 ly

Map locating star system
g NA

Location in Earth sky
g In constellation Hydra

Other names
g N1 1285
g YPC 3372.03
g Gliese 3877
g LP 914-54

Sci-fi mentionsg NA

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Wednesday, September 26, 2007

GJ 1128

Star type
g M4.5V

Distance from Earth
g 20.26 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA; 9.6%; NA

Brightness (xSol)
g 0.0272%

Metallicity
g NA

Comparison to Sol
g See chart (similar to Proxima)

Picture of star
g NA

Star system features
g NA

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g In constellation Ursa Major

Other names
g LHS 271
g L 100-115

Sci-fi mentions
g NA

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Tuesday, September 25, 2007

GJ 784

Star type
g M0V

Distance from Earth
g 20.24 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA; 58%; NA

Brightness (xSol)
g 2.151%

Metallicity
g NA

Comparison to Sol
g See chart (similar to Proxima)

Picture of star
g NA

Star system features
g NA

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g In constellation Telescopium

Other names
g CD-45 13677, Sm 50, Hip 99701

Sci-fi mentions
g NA

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Monday, September 24, 2007

GJ 338 AB

Star type
g A: M0.0
g B: K7.0

Distance from Earth
g 20.18 ly

Star Service No.
g NA

Age
g A: NA
g B: NA

Diameter/Mass/Temp (xSol)
g A: 67.5%; 35.9%; NA
g B: 65%; 60%-73%; NA

Brightness (xSol)
g A: 2.78% (an orange-red dwarf star similar to but much dimmer and redder than Epsilon Eridani; a flare star as well)
g B: 3.02%

Metallicity
g A: NA
g B: NA

Comparison to Sol
g A: See chart (similar to Proxima)
g B: NA

Picture of star
g A: NA
g B: NA

Star system features
g Stars A and B are separated on average by 108 AUs (16.675" of a semi-major axis using an NSTARS' average of 21.11 ly) in an eccentric orbit (e= 0.28) that takes 975 years to complete

Known planets
g A: Once suspected of having an unseen companion
g B: NA

Habitable zone
g A: Distance where an Earth-type planet would be "comfortable" with liquid water is centered around only 0.175 AU - well inside Mercury's orbital distance in the Solar System; at that distance from the star, such a planet would have an orbital period of about 34.5 days, just over a third of an Earth year.
g B: Water-zone orbital distance would be 0.17 AU with a period of about 30 days

Orbital map
g See animation

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g Inthe southwestern corner of Constellation Ursa Major, the Great Bear, which also encompasses the Big Dipper or Plow (Plough), west of Theta Ursae Majoris and north of Talitha (Iota Ursae Majoris) and Kappa Ursae Majoris

Other names
g A-B: Struve 1321 AB; Sigma 1321 AB
g A: NS 0914+5241 A; LHS 260; G 195-017; HIP 45343; HD 79210; BD+53 1320; LFT 634; LTT 12425; HD 79210; SAO 27178; Vys/McC 541 A; STF 1321 A; ADS 7251 A
g B: LHS 261; BD+53 1321 ; LFT 635; Hip 120005; HD 79211; G 195-18; SAO 27179; LTT 12426; Vys/McC 541 B; STF 1321 B; ADS 7251 B

Sci-fi mentions
g NA

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Sunday, September 23, 2007

GJ 2130 ABC

Star type
g A: M2 V
g B: M2 VJ
g C: M V

Distance from Earth
g 20.16 ly (alt. source says 46.2 ly)

Star Service No.
g NA

Age
g A: NA
g B: NA
g C: NA

Diameter/Mass/Temp (xSol)
g A: NA; 30%; NA
g B: NA; 19%; NA
g C: NA; 15%; NA

Brightness (xSol)
g A: NA
g B: NA
g C: NA

Metallicity
g A: NA
g B: NA
g C: NA

Comparison to Sol
g See chart (all stars similar to Proxima)

Picture of star
g A: NA
g B: NA
g C: NA

Star system features
g NA

Known planets
g NA

Habitable zone
g A: NA
g B: NA
g C: NA

Orbital map
g NA

View from star
g A: NA
g B: NA
g C: NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g In constellation Scorpius

Other names
g A: Hip 86961; CD-32 13297 A
g B: Hip 86963; CD-32 13297 B
g C: CD-32 13297 C

Sci-fi mentions
g A: NA
g B: NA
g C: NA

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Saturday, September 22, 2007

GJ 3454 AB

Star type
g A: M5 V
g B: M5 V

Distance from Earth
g 20.13 ly (alt. source says 27-28 ly)

Star Service No.
g NA

Age
g A: NA
g B: NA

Diameter/Mass/Temp (xSol)
g A: NA; 15%; NA
g B: NA; 13%; NA

Brightness (xSol)
g A: 0.18% (flare star)
g B: NA (likely a flare star)

Metallicity
g A: NA
g B: NA

Comparison to Sol
g A: See illustration (similar to Proxima)
g B: NA

Picture of star
g A: NA
g B: NA

Star system features
g NA

Known planets
g A: NA
g B: NA

Habitable zone
g A: NA
g B: NA

Orbital map
g Stars separated by 6 AUs

View from stars
g NA

Nearby stars
(Star systems with 10 light years)
g Luyten's Star: 7.7 ly (presumes star system is 20.13 ly from Sol)

Map locating star system
g NA

Location in Earth sky
g In constellation Canis Minor

Other names
g A: LTT 17993 A; G-89-32 A; Nl 654 A
g B: LTT 17993 B; G-89-32 B; Nl 654 B

Sci-fi mentions
g A: NA
g B: NA

Friday, September 21, 2007

GJ 1221

Star type
g DXP9 VII (white dwarf)

Distance from Earth
g 20.03 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA; 50%; NA

Brightness (xSol)
g 0.008%

Metallicity
g NA

Comparison to Sol
g See chart

Picture of star
g NA

Star system features
g NA

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g In constellation Draco

Other names
g LHS 455
g EGGR 372
g LP 044-113

Sci-fi mentions
g Lies in operation area of Fifth Fleet in “Full Thrust,” a miniatures war game

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Thursday, September 20, 2007

2MASS 0937+2931

Star type
g T6 Vp (brown dwarf)

Distance from Earth
g 20 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA

Brightness (xSol)
g NA

Metallicity
g NA

Comparison to Sol
g NA

Picture of star
g NA

Star system features
g Very recently discovered (during early 2000s)

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g NA

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g NA

Other names
g NA

Sci-fi mentions
g NA

Wednesday, September 19, 2007

HN Librae

Star type
g M3.5V

Distance from Earth
g 19.95 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA; 22%; NA

Brightness (xSol)
g 0.1065

Metallicity
g NA

Comparison to Sol
g See chart (similar to Proxima)

Picture of star
g NA

Star system features
g NA

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g See sky map

Nearby stars
(Star systems with 10 light years)
g Gl 581 (nearest star)

Map locating star system
g See stellar map (listed as “Wolf 1481”)

Location in Earth sky
g In constellation Libra

Other names
g GJ 555
g BD-11 3759
g LHS 2945
g Hip 75213
g Wolf 1481

Sci-fi mentions
g NA

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Tuesday, September 18, 2007

Delta Pavonis

Star type
g G8

Distance from Earth
g 19.92 ly

Star Service No.
g NA

Age
g Probably older than Sol and in the range of 5-7 Gy; the star is unusually bright for its spectral type, and so may be becoming a subgiant star that is beginning to evolve off the main sequence, as it begins to fuse the increasing amounts of helium "ash" mixed with hydrogen at its core

Diameter/Mass/Temp (xSol)
g 106%; 110%; 5700 K

Brightness (xSol)
g 118%
g Luminosity has increased 60% since it became a zero-age main sequence star

Metallicity
g 95%-270%

Comparison to Sol
g See chart (virtually identical to Sun)

Picture of star
g See picture

Star system features
g Nearest sun-like star that is not a binary or trinary

Known planets
g None

Habitable zone
g An Earth-type planet would be "comfortable" with liquid water is centered around 1.09 AU; at that distance from the star, such a planet would have an orbital period of about 395 days. Probability of a habitable planet is 5.7%. Porto de Mello lists it as one of 13 nearby astrobiologically interesting stars.

Orbital map
g NA

View from star
g See sky map

Nearby stars
(Star systems with 10 light years)
g L 119-44: 5.8 ly
g L 205-128: 6.4 ly
g CD-45 13677: 7.3 ly
g CD-49 13515: 7.4 ly
g Hip 82725: 7.5 ly
g L 347-14: 7.7 ly
g Epsilon Indi ABC: 9.3 ly
g Beta Hydri: 9.3 ly
g CD-46 11540: 9.9 ly
g CD-44 11909: 10 ly

Map locating star system
g See stellar map (listed as “Delta Pav”)

Location in Earth sky
g Near the center of Constellation Pavo, the Peacock, west of Beta Pavonis

Other names
g LHS 485
g Hip 99240
g NSV 12790
g Del Pav
g HR 7665
g Gl 780
g HD 190248
g CD-66 2367
g CP(D)-66 3474
g SAO 254733
g FK5 754
g LTT 7946
g LFT 1520

Sci-fi mentions
g Dune (1965), novel by Frank Herbert. The planet Caladan is the third world of the Delta Pavonis system.
g Revelation Space (2000), novel by Alastair Reynolds. The planet Resurgam and the neutron star Hades are part of the Delta Pavonis system.
g The novelette "Sundowner Sheila" by F. Gwynplaine MacIntyre (published in Interzone 202, February 2006) takes place on Terra Nova, a planet orbiting Delta Pavonis in synchronous rotation with almost no libration, so that one hemisphere of the planet is in perpetual darkness, and the other hemisphere (known as Nevernight) is in perpetual daylight. "Sundowner Sheila" is narrated by a synthetic human who is assigned to a longitude on Terra Nova where Delta Pavonis is permanently at zenith, so that the sun is always directly overhead and the time of day is always noon.
g Transformers (1983) animated television series, “The Big Broadcast of 2006” episode. Delta Pavonis IV is the home of a race of humanoid cats. A malfunctioning hypnotic Quintesson signal drives the cats to attack a neighboring planet of humanoid dogs.
g "The Right Hand of Dextra" by David J. Lake. Home of the Dextrans, a semimobile plant intelligence.
g Known as "Benzar", home of the Benzites, in "Star Trek" universe. The Benzites appeared in "Star Trek: The Next Generation."
g A human colony was established on the planet Loki in this star system, in Robert Silverberg's novel "The Man in the Maze."
g Alien species gathat lives on planet orbiting main star in Chris Berman's novel “Ace of Aces.”

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Monday, September 17, 2007

82 Eridani

Star type
g G5V

Distance from Earth
g 19.77 ly

Star Service No.
g NA

Age
g More than 10 billion years old (as indicated by low metallicity and high space velocity, and its substantial galactic orbital eccentricity, though it does appear to have a slight overabundance of metals for its age)

Diameter/Mass/Temp (xSol)
g 92%; 97%; 5305 K

Brightness (xSol)
g 60%

Metallicity
g 29%-100%; metal poor

Comparison to Sol
g See chart (virtually identical in size to Sun)

Picture of star
g NA

Star system features
g Past spectroscopic analysis suggested that the star may have a dim companion in a close orbit, but no study presenting empirical data for evaluating that indication is available

Known planets
g None

Habitable zone
g An Earth-type planet would be "comfortable" with liquid water is centered around 0.80 AU, midway between the orbital distances of Venus and Earth in the Solar System. At that distance from the star, such a planet would have an orbital period of almost 275 days. Probability of a habitable planet is 5.7%.

Orbital map
g NA

View from star
g See sky map


Nearby stars
(Star systems with 10 light years)
g LP 944-20 (brown dwarf): 4.4 ly
g GJ 1061: 7.9 ly
g L 302-89: 8.1 ly
g Kapteyn's Star: 8.9 ly

Map locating star system
g See stellar map (listed as “82 Eri”)

Location in Earth sky
g Southern part of Constellation Eridanus, the River, southeast of Acamar (Theta1 Eridani)

Other names
g GJ 139, HD 20794, Hip 15510, LHS 19, e Eridani, e Eri, 82 Eri, HR 1008, CD-43 1028, CP(D)-43 354, SAO 216263, FK5 119, LTT 1583, LFT 277, GC 4000, YPC 703.00

Sci-fi mentions
g Planet around star has gravity slightly higher than Earth's in Robert Silverberg novel "The Man in the Maze"
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Sunday, September 16, 2007

J. Herschel 5173 AB

Star type
g A: K3 V
g B: M3.5-4.0 V

Distance from Earth
g 19.74 ly

Star Service No.
g NA

Age
g A: 10 by (may be an old disk star)
g B: Less than 1 Gyr

Diameter/Mass/Temp (xSol)
g A: 71%-80%; 82%; 4890 K
g B: 28%; 20%; NA

Brightness (xSol)
g A: 23%
g B: 0.0077%

Metallicity
g A: 85%
g B: 26%

Comparison to Sol
g A: See chart (similar to Alpha Centauri B)
g B: See chart (similar to Proxima)

Picture of star
g NA

Star system features
g Stars A and B separated by 43 AUs, which is just beyond the "average" orbital distance (semi-major axis) of Pluto in the Solar System
g Star system has two optical companions that are not gravitationally bound, which are themselves binary systems (Gl 783.1 A and B; and Gl 738.2 A and B).

Known planets
g A: None
g B: None; possibly Vega-like disk orbiting star

Habitable zone
g A: An Earth-type planet would be "comfortable" with liquid water is centered around only 0.48 AU, or between the orbital distances of Mercury and Venus in the Solar System. Such a planet would have an orbital period of about 134 days. Probability of habitable planet is 2%.
g B: An Earth-type planet would be centered around only 0.028 AU, where such a planet would complete an orbital period within 3.8 Earth days. Probability of habitable planet is less than 0.1%.

Orbital map
g NA

View from star
g See sky map

Nearby stars
(Star systems with 10 light years)
g CD-45 13677: 3.2 ly
g L 347-14: 4.5 ly
g CD-49 13515: 7.1 ly
g Hip 103039: 7.2 ly
g Lacaille 8760: 7.8 ly
g CD-27 14659: 9.8 ly
g CD-44 11909: 10 ly

Map locating star system
g See stellar map (listed as “CD-36 13940”)

Location in Earth sky
g Southeast corner of Constellation Sagittarius, the Archer, southeast of Theta1 and Theta2 Sagittarii

Other names
g A: HJ 5173 A
g A: HR 7703 A
g A: Gl 783 A
g A: LHS 486
g A: CP(D)-36 9037
g A: SAO 211885
g A: LTT 7988
g A: LFT 1529
g A-B: HD 19408 AB
g A-B: Hip 99461 AB
g A-B: LP 870-45 AB
g B: Gl 783 B
g B: CD-36 13940 B
g B: LHS 487
g B: LTT 7989
g B: LFT 1530
g B: HJ 5173 B

Sci-fi mentions
g NA

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Saturday, September 15, 2007

36 Ophiuchi ABC

Star type
g A: K1
g B: K1
g C: K5 V

Distance from Earth
g 19.52 ly

Star Service No.
g NA

Age
g A: 590 million years
g B: NA
g C: 8.8 Gy (range of 8.64 Gy to 8.96 Gy)

Diameter/Mass/Temp (xSol)
g A: 81%; 85%; NA
g B: 81%; 85%; 5140 K
g C: 72%; 71%; NA

Brightness (xSol)
g A: 28%
g B: 27%
g C: 8.7%

Metallicity
g A: 50%-98%
g B: 123%-246%
g C: 46%-100%

Comparison to Sol
g See chart (all stars similar to Alpha Centauri B)

Picture of stars
g NA

Star system features
g Stars A and B are separated "on average" by about 88 AUs (of a semi-major axis) in a highly eccentric orbit (e= 0.922) that swings between seven and 169 AUs and takes around 570 years to complete. Star C orbits the AB pair from around 4,370 to 5,390 AUs away and is a variable star.

Known planets
g A: None
g B: Existence of an unseen but massive substellar, fourth component around Star B is now thought to be unlikely
g C: None

Habitable zone
g A: The orbital distance where an Earth-type planet would have liquid water is centered around 0.54 AU - just beyond Mercury's orbital distance in the Solar System - where a planet's period would be about 167 days; probability of a habitable planet is 2.3%. Star probably is too young to support life, however.
g B: The orbital distance where an Earth-type planet would have liquid water is centered around 0.53 AU, just beyond the orbital distance of Mercury in the Solar System, where the orbital period would be almost 163 days; probability of a habitable planet is less than 2%
g C: The orbital distance where an Earth-type planet would have liquid water is centered around 0.30 AU, three fourths of Mercury's orbital distance of in the Solar System, where the orbital period would be over 76 days; probability of a habitable planet is less than 0.1% (if satellite-stabilized)

Orbital map
g See map

View from star
g Stars A-B: See sky map
g Star C: See sky map

Nearby stars
(Star systems with 10 light years)
g CD-32 13297: 3 ly
g MLO 4 ABC: 4.5 ly
g Wolf 630 ABC: 6.3 ly
g CD-44 11909: 6.4 ly
g Wolf 629 AB: 6.8 ly
g BD-12 4523 AB: 7.5 ly
g Gliese 674: 7.6 ly
g G 154-44: 8.2 ly
g GJ 588: 8.6 ly

Map locating star system
g See stellar map (listed as “36 Oph”)

Location in Earth sky
g In the southernmost part of Constellation Ophiuchus, the Serpent Holder or Snake Charmer, south of Theta Ophiuchi

Other names
g A: GJ 663 A
g A: HD 155886
g A: LHS 437
g A: 36 Oph A
g A: HR 6402
g A: CD-26 12026
g A: CP(D)-26 5858
g A: SAO 185198
g A-B-C: ADS 10417 ABC
g A-B: Hip 84405
g B: HD 155885
g B: GJ 663 B
g B: LHS 438
g B: 36 Oph B
g B: HR 6401
g B: HD 155885
g B: SAO 185199
g C: V2215 Ophiuchi
g C: GJ 664
g C: HD 156026
g C: Hip 84478
g C: LHS 439
g C: 36 Oph C
g C: Gl 663 C
g C: CD-26 12036
g C: CP(D)-26 5863
g C: SAO 185213

Sci-fi mentions
g Dune and other novels in the Dune universe by Frank Herbert. 36 Ophiuchi B is orbited by the planet Giedi Prime.
g Frontier: Elite II and Frontier: First Encounters, computer games. 36 Ophiuchi is a mining system. The population of the system is centered around the first moon of 36 Ophiuchi C.
g Military force sent there to "liberate" colony in G. David Nordley's story "To Climb a Flat Mountain"
g In the "Star Trek" universe, this star system is home to the planet Ophiuchus III, a colony world that was being settled in the late 23rd century. Women were scarce enough there that intergalactic rogue Harry Mudd saw an opportunity in bringing them in from other worlds, during "The Original Series" episode "Mudd's Women". In "The Animated Series" episode "Mudd's Passion", Harry Mudd once visited Ophiucus VI, where he conned two miners out of a year's supply of dilithium crystals using fake Federation vouchers. The two planets probably orbit Star C.

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Friday, September 14, 2007

GJ 908

Star type
g M1.0 Ve

Distance from Earth
g 19.47 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA; 51%; NA

Brightness (xSol)
g 3.13% (flare star)

Metallicity
g NA

Comparison to Sol
g See chart (similar to Proxima)

Picture of star
g NA

Star system features
g NA

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g See sky map

Nearby stars
(Star systems with 10 light years)
g GJ 1286: 4.6 ly
g G 158-27: 5.1 ly
g EQ Pegasi ABCD: 6.3 ly
g L 722-22 AB: 6.6 ly
g Van Maanen's Star: 6.8 ly
g BD+04 123: 7.5 ly
g BD+15 4733 AB: 7.6 ly
g Gl 876: 7.7 ly
g LP 701-29: 9.6 ly

Map locating star system
g See stellar map (listed as “Lalande 46650”)

Location in Earth sky
g In constellation Pisces

Other names
g Lalande 46650
g Hip 117473
g LHS 550
g BD+04 4774
g BR Piscis
g LP 935-18

Sci-fi mentions
g The world Cyteen orbits this star in C.J. Cherryh's fiction

Thursday, September 13, 2007

Eta Cassiopeiae AB

Star type
g A: G3 (habitable)
g B: K7 (habitable)

Distance from Earth
g 19.42 ly

Star Service No.
g NA

Age
g A: 3.205 by (but appears to be more evolved then Sol)
g B: NA

Diameter/Mass/Temp (xSol)
g A: 98%-101%; 90%-110%; 5600/3800 K
g B: 66%; 56%; NA

Brightness (xSol)
g A: 120%
g B: 3%

Metallicity
g A: 63%-68%
g B: 63%-68%

Comparison to Sol
g A: See chart (similar to Sol)
g B: See chart (similar Alpha Centauri B)

Picture of star
g A: See picture
g B: See picture (Star A is bright white; Star B is yellow-orange.)

Star system features
g Star A and B are separated by an "average" distance of 71 times the Earth-Sun distance (AU) (of a semi-major axis) in an eccentric orbit (e= 0.497) of about 480 years, so that the two stars get as close as 36 AU and as far away as 107 AU

Known planets
g A: None
g B: None

Habitable zone
g A: Distance from star where an Earth-type planet would be "comfortable" with liquid water is centered around 1.13 AU ; such a planet would have an orbital period of about 1.15 years. Probability of a habitable planet is 5.7%.
g B: Liquid water zone would be centered around 0.18 AU, where the orbital period would be 37 days. Probability of a habitable planet: is 0.1% (if planet is satellite-stabilized).

Orbital map
g See orbital map

View from star
g See sky map

Nearby stars
(Star systems with 10 light years)
g BD+56 2966: 4.9 ly
g Mu Cassiopeiae 2: 5.4 ly
g EV Lacertae AB: 7.8 ly
g Kruger 60 AB: 8.2 ly
g Groombridge 34 Aab,B: 8.7 ly
g Stein 2051 AB: 9.2 ly

Map locating star system
g See stellar map

Location in Earth sky
g In the central part of Constellation Cassiopeia, the Lady of the Chair, northeast of Schedar (Alpha Cassiopeiae) and southwest of Mu Cassiopeiae

Other names
g Achird
g Gliese 34 AB
g HD 4614 AB
g The Third Star of Wang Liang
g A: Hip 3821
g A: LHS 123
g A: Eta Cas
g A: 24 Cas
g A: HR 219
g A: BD+57 150
g A: SAO 21732
g A: LTT 10287
g A: LFT 74
g A: Wolf 24
g A: Struve 60
g A: ADS 671 A
g B: LHS 122
g B: ADS 671 B

Sci-fi mentions
g "Terra Nova", episode of Star Trek: Enterprise television series. The planet Terra Nova, also known as Eta Cassiopeia III (sic), is located in the Eta Cassiopeiae system.
g Frontier: Elite II and Frontier: First Encounters, computer games. The Federation has a naval base in the Eta Cassiopeiae system.

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Wednesday, September 12, 2007

GJ 588

Star type
g M3

Distance from Earth
g 19.35 ly

Star Service No.
g NA

Age
g NA

Diameter/Mass/Temp (xSol)
g NA; 46%; NA

Brightness (xSol)
g 1.83%

Metallicity
g NA

Comparison to Sol
g See chart (similar to Proxima)

Picture of star
g NA

Star system features
g NA

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g See sky map

Nearby stars
(Star systems with 10 light years)
g NA

Map locating star system
g NA

Location in Earth sky
g In constellation Lupus

Other names
g NSV 7119
g Hip 76074
g LHS 397
g LTT 6210
g CP-40 9712

Sci-fi mentions
g NA

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Tuesday, September 11, 2007

Ross 882 AB

Star type
g A: M4.5Ve
g B: M5.5Ve

Distance from Earth
g 19.35 ly

Star Service No.
g NA

Age
g A: NA
g B: NA

Diameter/Mass/Temp (xSol)
g A: NA; 22%; NA
g B: NA; NA; NA

Brightness (xSol)
g A: 0.1146%
g B: NA

Metallicity
g A: NA
g B: NA

Comparison to Sol
g See chart (similar to Proxima)

Picture of star
g NA

Star system features
g NA

Known planets
g NA

Habitable zone
g NA

Orbital map
g NA

View from star
g See sky map

Nearby stars
(Star systems with 10 light years)
g Luyten’s Star: 7.1 ly
g Procyon AB: 8 ly

Map locating star system
g See stellar map

Location in Earth sky
g In constellation Canis Minor

Other names
g YZ Canis Minoris
g HIP 37766
g Gl 285
g LHS 1943

Sci-fi mentions
g NA

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Monday, September 10, 2007

Gliese 570 ABCD

Star type
g A: K4 V - K5
g B: M1 V
g C: M3 V
g D: T8 (brown dwarf)

Distance from Earth
g 19.2-19.26 ly

Star Service No.
g NA

Age
g A: NA
g B: NA
g C: NA
g D: 2-5 by

Diameter/Mass/Temp (xSol)
g A: 77%; 76%; NA
g B: 66%; 55%; NA
g C: NA; 35%; NA
g D: NA; 50 +/- 20 Jupiters; 900° F (coolest brown dwarf known)

Brightness (xSol)
g A: 15.6%; the star brightens and dims by about 50 percent over a a period of 10 days due to large star spots
g B: 1.9%
g C: 0.3%
g D: NA

Metallicity
g A: 102%
g B: 102% (?)
g C: 102% (?)
g D: NA

Comparison to Sol
g A: See chart (smaller than Alpha Centauri B but larger than GJ 205)
g B: See chart (similar to Proxima)
g C: See chart (similar to Proxima)
g D: See chart (similar to Gliese 229B)

Picture of star
g A: See picture (star is above a pair)
g B: See picture (star is one of pair below single star)
g C: See picture (star is one of pair below single star)
g D: See picture
g D: Artist’s interpretation of brown dwarf orbiting Stars A, B and C

Star system features
g Star A and the close binary pair BC have a wide average separation of about 190 AUs, moving in an eccentric orbit (e= 0.20) that lasts some 2,130 years; B and C pair of stars have an average separation around 0.79 AUs in a highly eccentric orbit (e= 0.765) lasting about 309 days; brown dwarf is separated from this trinary by more than 1,500 AUs
g Article about star system: "Astronomers Unveil Hot Photo of Cool Star"

Known planets
g A: None found
g B: None found
g C: None found
g D: None found

Habitable zone
g A: Star A's late spectral type and dim luminosity puts it possibly close to the lower limit of habitability for (multicellular) Earth-type plant and animal life, given the redness of its light and the increased risk of tidal locking from the closeness of the orbit necessary for liquid water on a planetary surface. The distance from Star A where an Earth-type planet would be "comfortable" with liquid water is centered around 0.40 AU -- within the orbital distance of Mercury in the Solar System. At that distance from the star, such a planet would have an orbital period of 104 days.
g B: Water zone orbit lies near 0.14 AU. Assuming that Star C does not perturb its orbital stability, a planet in Star B's water zone would have a period of about 25 days. However, tidal locking of such a closely orbiting planet would resulting in perpetual day on one side and perpetual night on the other.
g C: Water zone orbit lies near 0.056 AU. Assuming that Star B does not perturb its orbital stability, a planet in Star C's water zone would have a period of about 8.2 days. However, tidal locking of such a closely orbiting planet would resulting in perpetual day on one side and perpetual night on the other.
g D: Could possibly support life on a mall moon with a thick atmosphere; the star would glow dull red, like the embers of a dying fire, in the sky

Orbital map
g See map

View from star
g A: See sky map
g B: See sky map
g C: See sky map
g D: See sky map (virtually identical to Stars A, B and C)

Nearby stars
(Star systems with 10 light years)
g LP 914-54: 1.9 ly
g BD-11 3759: 3.6 ly
g Hip 72509: 4.8 ly
g Gl 581/HO Librae: 5.2 ly
g CD-25 10553 AB: 5.5 ly
g GJ 588: 7.1 ly
g L 768-119: 8.6 ly

Map locating star system
g See stellar map (Listed as “Lalande 27173”)

Location in Earth sky
g In the southwestern part of Constellation Libra, the Scales, southwest of Zebenelgenubi (Alpha2 Librae) and northwest of Sigma Libra; Star A is a relatively bright star in Earth's night sky

Other names
g HR 5568 ABCD, Lalande 27173 ABCD
g A: Hip 73184, LHS 387, HD 131977, BD-20 4125, SAO 183040, FK5 1391, LTT 5949, LFT 1161, LPM 551, Vys or McC 726 A, ADS 9446 A
g B: HD 131976, Hip 73182, BD-20 4123, SAO 183039, Vys or McC 726 B, LTT 5948, LFT 1160, LPM 550, ADS 9446 B, LHS 386
g C: ADS 9446 C, BD-20 4123 B, SAO 183039 B, Vys or McC 726 C, LHS 386 B

Sci-fi mentions
g NA

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