Star system has record eight exoplanets

Posted: December 14, 2017 by oldbrew in Astronomy, Astrophysics, News
Tags: ,

Kepler Space Telescope [credit: NASA]


The two nearest planets to the star Kepler-90 (90b and 90c) are very close to a 5:4 (i.e. first order) orbit ratio.

Nasa finds a distant star circled by eight planets, equal to the complement in our own Solar System, BBC News reports.

It’s the largest number of worlds ever discovered in a planetary system outside our own.

The star known as Kepler-90, is just a bit hotter and larger than the Sun; astronomers already knew of seven planets around it.

The newly discovered world is small enough to be rocky, according to scientists.

“This makes Kepler 90 the first star to host as many planets as our own Solar System,” said Christopher Shallue, a software engineer at Google, which contributed to the discovery.

Engineers from Google used a type of artificial intelligence called machine learning to find planets that were missed by previous searches.

The discovery was based on observations gathered by Nasa’s Kepler Space Telescope.

The new world, dubbed Kepler-90i, appears to be sizzling hot, orbiting its star once every 14.4 days.

Its parent star is very distant, lying 2,545 light-years away.

Some 3,500 exoplanets – worlds circling other stars – have been documented in recent decades.

Source: Star system has record eight exoplanets | BBC News

Comments
  1. Bloke down the pub says:

    Pity, no Goldilocks.

  2. Kip Hansen says:

    Both of these statements are false as written:

    1. It’s the largest number of worlds ever discovered in a planetary system outside our own.

    No “worlds” have been “discovered” anywhere outside of our own solar system. Not a single one. Worlds/planets have been inferred from the slight cyclic fluctuations in the brightness of distant stars. There are innumerable other possible causes of fluctuations in a distant star’s brightness. Fluctuations in a star’s brightness is assumed be to caused by planets passing between the star and our telescopes as the planets circle their Sun. Of course, that means that the plane of the orbit would have to coincidentally be exactly aligned to Earth and the planet would have to be large enough to obscure enough light to make a discernible (from Earth) difference. None of these things is as yet proven scientifically. They are, as we say, wishful thinking.

    2. The star known as Kepler-90, is just a bit hotter and larger than the Sun; astronomers already knew of seven planets around it.

    See above — no one knew anything about any seven planets at Kepler-90. Kelper-90 is 2,545 light-years away…..what might be making it pulse is subject to so much uncertainty that any statement about it is simply guesswork powered by wishful groupthink.

    Given all that — it MIGHT be true — some of it.

    I like the idea of exo-planets — and personally am sure that other stars have planets. Some day, we may have the technology to find out about them, until then, these types of statements should all be preceded by the words “may”, “might” and “if our theories and calculations are correct, this might mean…”.

  3. oldbrew says:

    K-90 planets are ordered by size, more or less — our solar system not so much, except that the four big ones are outside the four small ones (but are the ‘wrong’ way round).

  4. E.M.Smith says:

    Um… these two statements seem incompatible:

    The new world, dubbed Kepler-90i, appears to be sizzling hot, orbiting its star once every 14.4 days.

    Its parent star is very distant, lying 2,545 light-years away.

    IF the parent star is 2.5 light years away, the orbital circumference would be about Pi x 2.5 or 7.8 light years.

    To traverse that distance in 14.4 days requires travel of 0.54 light-years / day, or about 197 x the speed of light…

    I suspect a minutes got turned into years or some such…

    [reply] it’s 2,545 LY from Earth

  5. oldbrew says:

    They should really look at the synodic periods, but this is a start…

    Near resonances

    Kepler-90’s eight known planets all have periods that are close to being in integer ratio relationships with other planets’ periods; that is, they are close to being in orbital resonance. The period ratios b:c, c:i and i:d are close to 4:5, 3:5 and 1:4, respectively (4:4.977, 3:4.97 and 1:4.13) and d, e, f, g and h are close to a 2:3:4:7:11 period ratio (2:3.078:4.182:7.051:11.102; also 7:11.021). f, g and h are also close to a 3:5:8 period ratio (3:5.058:7.964). Relevant to systems like this and that of Kepler-36, calculations suggest that the presence of an outer gas giant planet facilitates the formation of closely packed resonances among inner super-Earths.

    http://en.wikipedia.org/wiki/Kepler-90#Near_resonances

  6. oldbrew says:

    HD 10180 could be a 9 planet system, but two are unconfirmed.

    HD 10180 is a Sun-like star in the southern constellation Hydrus that is notable for its large planetary system. Since its discovery, at least seven planets, and possibly as many as nine, have been observed orbiting it.

    http://en.wikipedia.org/wiki/HD_10180

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