THE SOUTHWORTH PLANETARIUM
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Altitude: 10 feet below sea level
Founded January 1970
Julian Date: 2458856.16
2019-2020: LXXXI
"Damn, existence is brilliant!"
THE DAILY ASTRONOMER
Tuesday, January 7, 2020
The Most Distant Exoplanet
We're almost a full week into the new year and we haven't yet really
visited Pandora's Jar. It has been tucked away in the impossible corners
of the star dome collecting dust. One issue with a workplace littered
with ancient amulets, terracotta jars, luminescent buttons, rotary knobs,
and myriad stars is that so much exists that is easily forgotten,
especially since it is all in the dark.
Anyway, onto today's astronomical query:
*"What is the most distant exoplanet? Are there exoplanets in other
galaxies?"*
-A friend in need
Greetings!
Please allow me to provide two answers to your questions. Hopefully, at
least one of them will prove helpful.
First, according to astronomers, the cosmos likely harbors thousands of
trillions of exoplanets. Not only do they revolve around stars in our
galaxy, but one will also find them in great abundance in other galaxies,
attached to stars expelled out of galaxies, and likely even millions, if
not billions, of rogue planets that became detached from their parent stars
and are hurtling aimlessly through the vast voids of both interstellar and
intergalactic space. Astronomers base this assumption on the number of
exoplanet detections they've confirmed since the advent of exoplanet
astronomy in the mid 1990s: 4164 as of this writing.
The ramifications of this conclusion are so staggering that our beautifully
sub-lunar, but lamentably finite, minds find it difficult to truly grasp
them. Next time you're standing outside admiring the tangerine clouds
in darkening twilight skies, realize that the number of worlds on which one
could behold the beguiling sight of a setting star is likely greater than
the number of seconds in a million years!
So, yes, planets abound throughout the ten million galactic superclusters
scattered throughout the cosmos. (Thirty years ago, many people
thought the Universe only contained nine planets.)
Now, the second answer involves exoplanet detections, which might have been
the focus on your question. What is the most distant exoplanet yet
found? How wonderful life would be if we could supply a simple answer.
We can't. First, the most distant confirmed exoplanet is called SWEEPS-11.
It revolves around the star SWEEPS J175902.67-291153.5, located in the
constellation Sagittarius at a distance of 27,710 light years from the
solar system. (It is closer to the real action around the galactic
center.)
The name derives from the "Sagittarius Window Eclipsing Extrasolar Planet
Search mission that located the planet in 2006. This planet is hot
Jupiter planet. Its radius is 1.13 times that of Jupiter (almost 1.5 times
greater in volume, but nearly ten times as massive.) It revolves around
the planet once every 1.8 days and is certainly not with its parent
star's habitable zone.
Next, no planet has yet been detected in another galaxy, EXCEPT (and I said
this issue wasn't going to be simple) that astronomers observed a
microlensing event in the Andromeda Galaxy
in 1999. During such an event, a massive foreground object causes a more
distant image to be doubled and magnified due to the gravitational lensing
effect. The microlensing event in Andromeda, dubbed PA-99-N2, might
have provided evidence of an exoplanet. This detection remains
unconfirmed. It the exoplanet's existence is ever confirmed, it would
represent the first exoplanet discovered in another galaxy: about 2.1
million light years away! Again, we are certain they exist in vast
numbers: the problem is detecting them from such a great distance.
[image: RX_J1131.jpg]
Then again, in 2018, analysis of the quasar microlensing event RX
J1131-1231 (see image above) might have provided evidence of 2000 rogue
planets about 3.8 billion light years away! While these findings remain
unconfirmed, it is likely that these will be the first rogue planets
detected at such a vast distance!
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