Saffar (exoplanet)

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Exoplanet
Saffar

Artist's impression of the planet and its central star

Artist's impression of the planet and its central star
Constellation Andromeda
Position
equinox : J2000.0
Right ascension 01h 36m 47.843s
declination + 41 ° 24 ′ 19.65 ″
Orbit data
Central star Titawin A
Major semi-axis 0.05922166 ± 0.00000020 AU
eccentricity 0.02150 ± 0.00070
Period of circulation 4.617033 ± 0.000023
Further data
Minimum dimensions 0.6876 ± 0.0044 M J
distance 13.57 ± 0.02 pc
history
discovery Marcy et al.
Date of discovery 1996
Catalog names
υ And b, 50 And b, HR 458 b, GJ 61 b, HD 9826 b

Saffar ( Upsilon Andromedae b , also abbreviated υ And b ) is an exoplanet that the approximately 44.25 light years from the sun distant main sequence star Titawin A in the binary system Titawin ( Upsilon Andromedae ) in the constellation Andromeda orbits. It is the innermost of the four known planets in the star's planetary system .

Origin of name

Like all exoplanets, Saffar was originally designated with the star's official name and a lowercase letter, according to the order in which it was discovered. After a public IAU competition , on December 15, 2015, it was given an official name after Ibn as-Saffar , an 11th-century Arab astronomer in al-Andalus .

discovery

The planet was discovered in June 1996 by a team of astronomers led by Geoffrey Marcy and R. Paul Butler using the radial velocity method and its discovery was published in 1997 together with the planets Tau Bootis b and 55 Cancri b . It was one of the first known exoplanets around a main sequence star.

properties

Saffar orbits its central star at a distance of only around 0.06 AU in approximately 4.6 days. Its minimum mass is a little more than two thirds of the mass of Jupiter . It belongs to the planetary class of the Hot Jupiters , which as gas giants orbit their central star at a very short distance. The actual mass of υ And b could be around 1.4 Jupiter's masses, the orbital inclination around 25 °.

Measurements by the Spitzer Space Telescope indicate a temperature difference on the planet between the side facing away from or facing the star of around 1,400 ° C. Assuming a Jupiter-like atmosphere, Saffar could have clouds of silicate and iron high in its atmosphere. According to polarimetric measurements, the planet has a geometric albedo of 0.35 and is thus comparable to the planet Neptune in the solar system.

Individual evidence

  1. ↑ VizieR: HIP 7513. Retrieved May 17, 2015 .
  2. ↑ a b c d NASA Exoplanet Archive: ups And b. Retrieved May 17, 2015 .
  3. ↑ International Astronomical Union: NameExoWorlds - The Approved Names. Retrieved January 3, 2016 .
  4. ^ Butler, R. Paul et al .: Three New "51 Pegasi-Type" Planets . bibcode : 1997ApJ ... 474L.115B .
  5. ^ Curiel, S. et al .: A fourth planet orbiting υ Andromedae . bibcode : 2011A & A ... 525A..78C .
  6. ^ McArthur, Barbara E. et al .: New Observational Constraints on the υ Andromedae System with Data from the Hubble Space Telescope and Hobby-Eberly Telescope . bibcode : 2010ApJ ... 715.1203M .
  7. ↑ Harrington, J .; Hansen, BM; Luszcz, SH; Seager, S .; Deming, D .; Menou, K .; Cho, JY; Richardson, LJ: The phase-dependent Infrared brightness of the extrasolar planet upsilon Andromedae b . arxiv : astro-ph / 0610491 .
  8. ↑ Sudarsky, David et al .: Theoretical Spectra and Atmospheres of Extrasolar Giant Planets . arxiv : astro-ph / 0210216 .
  9. ↑ Berdyugina, SV; Berdyugin, AV; Piirola, V .: Upsilon Andromedae b in polarized light: New constraints on the planet size, density and albedo . arxiv : 1109.3116 .