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Exoplanetary Scratchpad

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Titawin (Upsilon Andromeadae) is a nearby (44 ly) multi-star system which is the first multiplanet system found around a main sequence star or a multi-star system. The main star around which the planets orbit is a yellow-white star somewhat younger than the sun and its companion is a red dwarf in a wide orbit. It is one of the most well studied non-transiting star systems. Roaster Saffar (b, 0.05 au, 0.62 MJ, e=0.013, and the nearest true Hot Jupiter to Earth) is nicknamed the Fire and Ice Planet because it is hot on one side and cold on the other. The hottest parts of the planet are near the trailing side terminator at the equator, due to high velocity winds transporting heat to the night side. This is 80deg offset from the starward pole and a much greater offset than other observed hot Jupiters. This threw astronomers off and caused them to doubt the wind-theory, though later observations of other planets have shown that winds indeed can travel fast enough to cause this. Stability studies and observations suggest its diameter is 1.8 DJ, rather large for a planet its age. The middle planets Samh (c, 0.83 au, 1.8 MJ, initially thought to possibly be a brown dwarf star, e=0.224) and Majriti (d, 2.5 au, 10.2 MJ, e=0.26) have had their inclinations and masses determined with astrometry, the first determination of relative inclinations of exoplanets. They are very eccentric and highly inclined to each other (30 deg). Planet scattering was thought to be a source until the outermost planet was discovered. This is planet e (5.2 au, 1.05 MJ, e = 0.005), which is the most Jupiter-like exoplanet known, and is in 3:1 resonance with planet d. Planet c is in the habitable zone, though any habitable moons would see drastic temperature swings. The star appears to have no Kuiper-belt like disc, perhaps due to its companion star sweeping away this material. One of the first 20 exoplanet systems allowed to be given common names by the IAU. The star is named after an important city in Morocco that bridged the Spanish and Arab worlds. The planets are named after famous Andalusian astronomers.

My Thoughts[]

It seems planet e is not up for being named, not sure if it's that it's not confirmed, or if it just hasn't been known long enough to be named. It's not mentioned in a 2014 paper and not marked as confirmed in Sol Station. It is listed in the Extrasolar Planetary Encyclopedia though, but it's not been updated since discovery. If the middle planets inclinations are known, shouldn't we know their precise mass, enough not to think they could be Brown Dwarfs? Or is only relative inclination known? This system seems to buck the trend that a Hot Jupiter means there's no other planets around the star. Is the caveat that if there are other planets, they tend to have high eccentricities and inclinations? Amazing that a Jupiter Analog could exist in this "inverted" solar system, where the extra mass in the star probably boosted the mass of its inner planets.


Its constellation is the chained maiden. It was discovered by Americans.

- Rayeta - royalty and has some princess daughters

Upsilon Andromedae System Web Pages[]

Upsilon Andromedae System In the News[]

Planet b Discovered (1996)[]

Planet b Studies (1996-2005)[]

Planet c and d Discovered (1999)[]

Entire System Extrapolated From Planet d (1999)[]

No Circumstellar Disk Found (1999)[]

System Stability (1999-2004)[]

Mass Estimation (1999-2001)[]

Dynamic Origin (1999-2001)[]

Apsidal Alignment (2001-2002)[]

Water MASER Detected (2002)[]

Star B Discovered (2002)[]

Star-B and Dynamics (2002)[]

Origin of Eccentric Planets (2002-2005)[]

Hubble Astrometric Studies (2003)[]

Theoretical Disk Structure (2003)[]

Search for Radio Emissions (2004-2005)[]

Stattered Planet? (2004-2005)[]

Habitability Studies (2004)[]

Planet b Found to Be Half Hot Half Cold (2006)[]

Outer Planets Found to be Tilted 30degrees (2010)[]

Mysterious Hot Spot on Planet b (Oct 2010)[]

Jupiter Analog e Discovered (2010)[]

Model Using HD 209458 Data Explains Wind Source of Offset Hot Spots (2011)[]

System in 3D (2015)[]

One of the Top 20 Exoplanetary Systems First Up For Naming (May 2015)[]

See Also[]