Ino

Ino (30 Arietis Bb, P375) is a which orbits the yellow-white   , meaning the star is larger, hotter and thus brighter than our. It is approximately 133 s or 41 s away towards the  in the caelregio Araneus.

Ino has a very similar orbital distance from the star as Earth from the Sun, although Ino is hotter than Earth because the parent star is more luminous than our Sun and the planet is emitting heat from its interior.

is named after the queen of in. This planet had a former name after a historical Greek region on the southern coast of Black Sea where it is now modern-day northeastern Turkey.

Discovery and chronology
Ino was discovered on November 27, 2009 (which was on ) using a precise from  installed in  in. was the discoverer.

Ino is the 368$J$ extrasolar planet discovered overall, 342$J$ since 2000, and 70$J$ in 2009. It is also the 7$J$ exoplanet discovered in the constellation Aries (2$J$ in 2009) and 45$J$ in the caelregio Araneus (9$⊕$ in 2009). Ino is the first and only planet discovered in the 30 Arietis B system, hence the designations 30 Arietis Bb (a is not used because the parent star uses this letter to reduce confusion) and 30 Arietis B P1. Note that the chronology does not include speculative s (objects with minimum masses below 13 M$⊕$ but with speculative true masses above 13 M$⊕$).

Orbit
Ino takes 29 s or 11 s to revolve around the star in a at an  of 31.54 km/s or 19.60 mi/s, which is slightly faster than Earth's. Ino orbits at 4.77 microparsecs (μpc) or 147 s (Gm) from the star, which is similar to the distance between  and the Sun, but its  is much higher. At, the planet's closest distance to the star is 3.39 μpc or 105 Gm, which is slightly closer to the star than to the Sun. At, the planet's farthest distance to the star is 6.14 μpc or 189 Gm, which is half-way between the orbits of Earth and. The circumference of its orbit is 29.49 μpc or 910 Gm, which is 2 average radius. The area of its orbit, that is, the area of space inside the planet's orbit, is 68.38 μpc² or 65105 Gm². The of its orbit is about 50°.

Parent star observation and irradiance
As viewed from the planet, the star appears to be two times brighter than the Sun as seen from Earth. Although since the planet's orbit is eccentric, the brightness of the star as seen from Ino changes. At periastron, the star appears to be twice as bright as the average apparent brightness while at apastron would appear to be 60% as bright. The apparent diameter of the star is 20% larger than the full moon and sun as seen from Earth. Like apparent brightness, the apparent diameter of the star also changes throughout its orbit because of its high eccentricity. At periastron, the star would appear to be 41% larger than its average value while at apastron, the star would appear to be 78% as large.

Because the planet orbits at similar distance from 30 Arietis B as Earth is from the Sun, Ino should receive similar as Earth's, but it is not the case because 30 Arietis B emits twice as much energy than the Sun over the same timespan. This corresponds that Ino receives twice as much energy per square meter as Earth's. Because Ino orbits so eccentrically which causes distance from the star to vary considerably, so does irradiance. At periastron, the planet receives twice the average energy per square meter while at apastron, it receives just 60% of the average energy.

Rotation
Ino takes a fast 4.3 hours to rotate in the same direction is its orbit once on its axis and tilts 0° to the plane of its orbit. Since Ino is not tilted on its axis, each day and night always last 2.3 hours. The tilt of this planet is such that both poles point to the Earth's equatorial constellations: (in Noctua) for the, and  (in Hippocampus) for the.

Mass and size
Ino has 12.95 es or 4115 es, which is extremely close to the boundary between planets and brown dwarfs at 13.00 Jupiter masses or 4132 Earth masses. In the planetary mass classification, Ino is a super-Jupiter. Its mean radius is 1.10 times that of Jupiter or 76 megameters, meaning at a distance of 41 parsecs, this planet has an of 25 s, six billionth the size of the. It can fit 1749 Earths inside Ino! Since Ino is much more massive and only slightly bigger than, this planet is very dense and has very strong gravity. The density of this planet is close to 13 g/cm³, which is over twice as dense as Earth and nearly 10 times denser than Jupiter.

Gravitational influence
The gravitational strength on Ino is more than 28 times stronger than Earth's, nearly 11 times stronger than Jupiter's, and stronger than even our Sun by 1.5%. The surface gravity is derived from dividing its mass by square of its radius, meaning if this planet is bigger, then its gravitational field would be weaker. If you weigh 150 on Earth, you'll weigh 4251 pounds or over 2 s on Ino.

Since the gravity and s of Ino are so strong, the maximum distance from the planet where a 3 g/cm³ moon tear apart by tidal forces, called its, stretches very far from the planet. The roche limit is 41% the Earth–Moon distance at 2.05 planetary radii or 158 s. The is 107 times as distant as the roche limit at roughly 16 gigameters. Ino's gravitational field is so strong that moons would have to orbit within the roche limit in order for a moon to always face the same side of the planet. However, a moon can be at that orbit without tearing apart by tidal forces as long as its density is at least 4 g/cm³. If it is in its, it would have an of 87.3 km/s or 54.2 mi/s. Since the planet takes 4.3 hours to rotate, then a moon would take 4.3 hours to orbit the planet at stationary orbit.

Interior
Below its outer envelope lies mantle of pressurized hydrogen, below it lies and, below it lies liquid , and then solid metallic hydrogen. At the planet's center lies a rocky/metallic core with a temperature about 94,000°C or 169,000°F, much higher than Jupiter's due to its high mass. Ino has the interior structure similar to Jupiter and.

Atmosphere
The main gases of the atmosphere are and  as well as trace amounts of, , , , , , and. The of this planet, based on it orbital distance and parent star's luminosity, is 31°C or 88°F, but the surface temperature (1-bar layer) is over 380°C or nearly 720°F. This unexpectedly high temperature is caused by a great deal of caused by its strong. At that temperature, there are no chemicals suitable for the formation of clouds.

Since there are no clouds on Ino, there are no storms, but winds may still blow. The winds on the planet may reach as high as 3000 mph (5000 kph) due to its very rapid rotation and high temperature. Most of the winds are powered by since the planet radiates three times more heat from the interior than it receives from 30 Arietis B.

Magnetic field
Ino has a far more powerful than, the planet with the strongest magnetic field in our. This planet has a magnetic field strength of 118, compared to 4.28 Gauss for Jupiter and 0.307 for Earth.

That powerful magnetic field is produced by its rapid rotation that causes very fast movements of liquid metallic hydrogen in the mantle that produces s. This magnetic field can stretch up to 45 AU, which is longer than the average distance between the Sun and. The center of the magnetic field is not at the physical center of the planet, but it is offset by about 8 megameters.

Moons and rings
Ino is so massive that there are over 300 moons with diameters at least 1 km or more. Most moons are tiny, but some are large. The largest moon has mass 0.81 Earth masses and has a thick -rich atmosphere with a liquid water and possibly. The second largest has mass 0.33 Earth masses and it is a barren world and volcanic. The third largest has about the size of Mars with surface pockmarked with craters. There are seven moons that are larger and more massive than our Moon. Ino has a faint ring system leftover from the formation of the planet and its moons over 900 million years ago.

Future studies
Ino is speculated that it does not transit the star because the orbital plane is speculated not to be edge-on. The inclination of this planet places halfway between face-on and edge-on. However if Ino does 30 Arietis B (which only occurs when the orbital inclination is close to 90°), then its inclination,, radius (which can calculate derivative properties like density and surface gravity using mass), temperature, and other parameters can be constrained as well as studying its atmosphere and looking for moons and rings in orbit. If Ino does not transit its star, then this planet can be studied by or  instead. Finding planets with direct imaging orbiting as close as 1 AU from the star is difficult because the glare of its star prevents astronomers from seeing close-orbiting planets. But in 2010, there is a new direct imaging instrument, called, that can detect and characterize planets as close to their stars as 1 AU (right where Ino orbits). On the otherhand, shall study the astrometry of this planet and a thousand others, constraining their inclinations. Once inclination is known, it will determine whether this object is actually a planet or a brown dwarf.