The newly found exoplanet therefore sets a new record as the smallest planet discovered around a solar-type star
"I see no problem with there being more than 15 Earth masses of accretable material around a solar-type star
," Christiansen said in the Princeton statement.
He said it works better than our own solar-type star
without a companion and there is a plenty of room for several habitable planets and these may be places where many worlds in system could be habitable.
The abundant amount of oxygen and absence of hydrogen indicate that the destroyed star was a white dwarf, the end phase of a solar-type star
that has burned its hydrogen leaving a high concentration of oxygen.
For an Earth-size planet transiting a solar-type star
, the change in brightness is less than 1/100 of 1 percent.
Tycho G, as she called it, is a solar-type star
slightly offset from the remnant's center (S&T: February 2005, page 22).
The first exoplanet around a solar-type star
, discovered by Michel Mayor and Didier Queloz in 1995, is an excellent example of the former.
A NEW FOUR-PLANET SYSTEM The European group led by Michel Mayor (Geneva Observatory, Switzerland) has found the second four-planet system around another solar-type star
. The four planets orbit Mu Arae (HD 160691), a G3 star 50 light-years from Earth.
It has already produced a "movie" of star-spots being carried around the young, solar-type star
[Kappa.sup.1] Ceti by the star's rotation.
A classic example of a secular resonance can be found in Upsilon Andromedae, which will be forever enshrined in history books as the first known multiple-planet system around a solar-type star
other than the Sun.
(Astronomers call all such elements "metals," misleading though the term is, for reasons rooted in the history of spectroscopy.) In fact, it's hard to find a very metal-rich solar-type star
where a giant planet has not turned up when a search has been done.