Of the ~25 directly imaged planets to date, all are younger than 500Myr and all but 6 are younger than 100Myr1. Eps Ind A (HD209100, HIP108870) is a K5V star of roughly solar age (recently derived as 3.7-5.7Gyr2 and Gyr3). A long-term radial velocity trend 4,5 as well as an astrometric acceleration6,7 led to claims of a giant planet2,8,9 orbiting the nearby star (3.6384±0.0013pc10). Here we report JWST coronagraphic images that reveal a giant exoplanet which is consistent with these radial and astrometric measurements, but inconsistent with the previously claimed planet properties. The new planet has temperature ~275K, and is remarkably bright at 10.65µm and 15.50µm. Non-detections between 3.5-5µm indicate an unknown opacity source in the atmosphere, possibly suggesting a high metallicity, high carbon-to-oxygen ratio planet. The best-fit temperature of the planet is consistent with theoretical thermal evolution models, which are previously untested at this temperature range. The data indicates that this is likely the only giant planet in the system and we therefore refer to it as “b”, despite it having significantly different orbital properties than the previously claimed planet “b”.
Epsilon Indi planet A is two thirds the size of the Sun, but has roughly the same temperature as the Earth. As a gas giant, its atmosphere may be as hostile to human life as Jupiter's, and with 12,000 times the surface of the Earth, a nightmare for climate modeling, but its huge size comes with one very attractive feature.
The Solar System has a narrow temperate zone. Most of its planets are nowhere near the temperature range of water-based life. But moons orbiting this 2.7 trillion square mile ball may share its moderate temperature. The superjupiter in question has mass enough to gravitationally host moons galore in a manner recalling the ancients epicyclic view of the solar system. But how many and how big?
What I learned about lunar and planetary scaling in preparing this 2006 WSJ column suggests the answer could be wonderful, for E Ind A is not only large enough to host a myriad of moons, some possibly Earth-sized, but so close at 12 light years that if we neighbors on any of then, we may already have something in common. At that distance they can hardly have missed our Sun shining as a second magnitude star in their night skies
THE WALL STREET JOURNAL
OP ED PAGE MARCH 14 2006
A Snowball Under The Sun
By Russell Seitz
When NASA's Cassini mission blasted off for Saturn in 1997 bearing the Huygens probe, the ringed planet had 18 moons, the first five spotted in the 17th century by the astronomers whose names the mission honors. It's not their fault they missed Enceladus. Baroque astronomers peered through telescope glass about as transparent as a bottle of crusted port.
Enceladus, the bright little moon now making headlines for its spouting geysers, had to wait until 1789, when Royal Astronomer William Herschel had the benefit of achromatic lenses clear as spring water, as well as Sir Isaac Newton's newfangled reflecting telescope. Such instruments racked up another 13 Saturnian satellites in the three centuries that followed. But even with the best and biggest telescopes, Enceladus is still not much to look at. Seen from Earth, it's the closest thing to a snowball under the sun.
Frosty white, and featureless at a distance, it is also rather small. While Titan, which Huygens discovered, is a comparatively titanic 2,500 kilometers in diameter, Enceladus is a modest 500-a dozen like it could hide behind our moon. But between Cassini's liftoff and arrival, earthbound astronomers used smart optics and small telescopes on space probes to add more than a baker's dozen, bringing the waxing list to a mind-bending 35: Albiorix, Atlas, Calypso, Daphnis, Dione, Enceladus, Epimetheus, Erriapo, Helene, Hyperion, Iapetus, Ijiraq, Janus, Kiviuq, Methone, Mimas, Mundilfari, Narvi, Paaliaq, Pallene, Pan, Pandora, Phoebe, Polydeuces, Prometheus, Rhea, Siarnaq, Skadi, Suttung, Tarvos, Telesto, Tethys, Thrym, Titan and Ymir.
In addition to enough mythical Greeks to populate several Boy Meets Nymph operas and Scandinavians sufficient for a sitcom sequel to Götterdämmerung, the cast includes Inuit sea deities and a refugee from the Celtic Otherworld. This less reflects DEI or PC than sheer exhaustion. The demiurge drain on new solar system names has cleared the shelves of Hindu handles, Gallic godlets and the African animist pantheon. Islam and Judaism are no help at all, and Asterix already has an asteroid as his namesake. Even postmodern astronomers blanche at the tentative name of the biggest ball of wax in the Kuiper belt. If Xena achieves textbook immortality, there's no polite way to stop the declension of her mooning companion as-what else-Gabrielle.
It can only get worse as telescopes get better. Saturn's latest squeeze, Daphnis, is such a midge she could be plunked down like the Flushing Perisphere for a War of the Worlds Fair in Kashmir without blocking the view of K2.
Mundilfari is even smaller-three and a half miles must be a galactic record for vertically challenged fathers of sun gods. If telescopes keep growing, and moons shrinking at their present rate, before the eon is out Texans may be using minor satellites to shoot quail.
Now that we have established that Enceladus is an object of very respectable size, what's all this about life out there? Not a whiff has been discovered, despite the presence of liquid water-but though there is as yet no sign of life in the neighborhood, NASA is understandably chuffed about discovering the neighborhood itself.
Yes, it's cold out there and there's no kind of atmosphere, except at the South Pole where sure as Old Faithful, the place has geysers galore, as in water gushing out of the ground and into direct sunlight. Just what makes this snowball spout remains an energetic mystery. Enceladus is way too light in both senses of the word for either solar heating or radioactive decay to be warming its core. It is also too far from massive Saturn for tidal forces to be flexing warmth into its frigid mix like a mass of sorbet or salt water taffy in mid-manufacture. Saturn's nearly identical ice moon, Mimas, takes more tidal stress, yet remains adamantly frozen. It has been so for a very long time, for its profoundly cratered surface boasts a black eye a third of its diameter, while Enceladus has the fresh-from-a-face-job look of something whose tectonic skin is rolling up and over at a goodly rate.
So something is warming it up big time. But what? We face a hot scientific debate as to what antediluvian energy source allows liquid water to bubble up out where frigid liquid nitrogen serves as morning dew. For the moment what matters is that the water in question is likely wet a stone's throw from the surface-a safe bet given that Enceladus surface gravity is so low that you could toss a dwarf half a mile. So even if this snowball is sterile today, it may present places where an ice fisherman in a space suit could lower away a bald Chia Pet into a fissure and bring up an alfalfa salad. This is not much of a First Contact story by H.G. Wells, Robert Heinlein or Truffaut-Spielberg standards, but cheer up-at least we're not on the menu. Yet.
