WILLIAM & DEBORAH HILLYARD

Extra Solar Planets

47 UMa is a stable Sun-type type G1V yellow dwarf star about 46 light-years away from Earth.  It is about 17% larger and 8% heavier than the sun with a surface temperature very slightl;y higher than the Sun.  It is thought to be somewhat older than the Sun at about 6 billion years old, compared to about 4.5 billion for the Sun, but other models and observations put it at anywhere from 4.4 to 8.7 billion years old.  Since 1996, three Jupiter type planets have been found in orbit around the star.  It is unlikely to host any terrestrial planets due to disruption from the very large inner planet, but it is possible for one to exist on the inner edge of the habitable zone.  Unfortunately, it is also likely to be a dry planet as the outer planets would probably have prevented water migrating that far inwards. 

While this system appears in the Visualization, it does not include the recent discovery of the outermost planet so is included under two planet systems. 

47 Ursae Majoris (47 UMa)

Planet Description (in order from the star; all quoted values are approximate)
47 UMa b Discovered in January 1996, it is the innermost planet in the 47 Ursae Majoris system.  It orbits its star at a distance of about 314 million km (c. 195 million miles) once every 1,078 days or 2.95 years, on a near circular orbit.  It weighs in at a minimum of 2.53 times the mass of Jupiter, so it is pretty big.  It is relatively cool at only 200K (-73ºC).  Depending on the degree to which the orbit is inclined to our line of site, it could be substantially heavier.
47 UMa c
This planet was discovered in 2001, and is the middle of three planet in the 47 Ursae Majoris system.  It orbits at a distance of about 540 million km (c. 336 million miles) once every 2,390 days or 6.55 years, but unlike 47 Uma b, it has a rather eccentric orbit varying between around 490 and 600 million km.  It weighs in at a minimum of a little over half (about 54%) of the mass of Jupiter.  Some uncertainty about its existence remained until it was confirmed in 2010.
47 UMa d
This planet was discovered in 2010, and is the outer of three planet in the 47 Ursae Majoris system.  It orbits at a distance of about 1.73 billion km (c.1.076 billion miles) once every 38.33 years, which is equivalent to being between Saturn and Uranus in our system.  Uma d, however, has a very eccentric orbit varying between around 1.46 and 2.01 billion km.  It weighs in at a minimum of about 1.64 times of the mass of Jupiter.
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