Devana

Devana (61 Virginis b, P378) is a which orbits the yellow   , which is similar to our. It is approximately 28 s or 9 s from towards the   in the caelregio Noctua.

Devana is the innermost of the three known planets in 61 Virginis system. Devana is super-Earth. The planet takes just four days to orbit the star and it is tidally locked.

is named after the equivalent of  goddess. Diana was the goddess of hunt and moon.

Discovery and chronology
Devana was discovered on December 14, 2009 by a team of astronomers led by. The team used the  mounted on the  in Hawaii and the  in New South Wales, Australia and found that the star 61 Virginis has three periodic variations in the. This implies evidence for a three-planet system around 61 Virginis, including Devana.

Devana is the 371$⊕$ exoplanet discovered overall, 345$⊕$ since 2000, and 73$⊕$ in 2009. Devana is the 16$⊕$ exoplanet discovered in the constellation Virgo (6$⊕$ in 2009) and 39$⊕$ exoplanet discovered in the caelregio Noctua (11$⊕$ in 2009). Since Devana is the first planet discovered in the 61 Virginis system, the planet receives the designations 61 Virginis b (a is not used because the parent star uses this letter to reduce confusion) and 61 Virginis 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
Devana orbits the star at an of 0.0503  (1 AU is the average distance between the Earth and the Sun) or 7.52  (million ), which is eight times closer to the star than  is to the Sun. Devana has a semi-circular orbit with an eccentricity of 0.1188. Devana's orbit varies from 0.0443 AU (6.63 Gm) to 0.0562 AU (8.41 Gm). The planet takes just 4.215 days, 101.2 hours or 364.2 s to make one complete trip around the star at an of 129.8 km/s, 80.7 mi/s, or 27.3 AU/yr. Devana is in a 1:9 with the middle known planet Tamar and 1:29 resonance with the outermost known planet Tuonetar.

Parent star observation and irradiance
Viewed from Devana, the parent star would have a −32.99 compared to −26.74 for the magnitude of the Sun seen from Earth. Observed from Devana, 61 Virginis would appear to be 316 times brighter than the Sun seen from Earth. Viewed from Devana, the parent star would have an of 10.1° on average, which is 20 times the angular diameter of the  we sometimes see at night.

Every square meter of the surface, Devana receives 405.7 kilowatts of stellar energy compared to just 1.4 kilowatts of solar energy for Earth. This means that Devana receives nearly 300 times more energy per square meter from 61 Virginis than Earth receives from the Sun. That's because the planet is orbiting of the Earth-Sun distance from that energy source, and  is inversely proportional to the square of the planet's distance from the star. If we square that reciprocal, we get 400, but the planet receives only 300 said times, meaning that the parent star would have to be as luminous as our Sun to account for that value. In reality, the parent star is almost exactly solar luminosity!

Rotation
Devana is, meaning the planet rotates at a same rate as its revolution around the star. Since the planet takes 4.215 days to orbit the star, then it would also take 4.215 days to rotate once on its axis. So the year on Devana lasts exactly one day compared to 366 Earth days in an Earth year. The planet tilts 12.6° to the plane of its orbit, which is half the Earth's tilt of 23.4°. The planet's points to the constellation  (in Tarandus), while the  points to the constellation  (in Araneus).

Mass and size
Devana is a low-mass planet, massing 5.26 es, classifying it as super-Earth in the planetary mass classification scheme. This planet is more than twice as large as Earth at 2.12. Devana has a density of 3.06 g/cm³, meaning that it is less dense than Earth, meaning it has greater ratio of light-weight materials relative to heavy-weight materials than Earth.

Gravitational influence
The gravitational force of Devana is 17% stronger than Earth's. So if you weigh 150 on Earth, you would weigh 176 pounds on Devana.

Since Devana orbits so close to the star, the would be very small, at a radius of just over nine planetary radii. Like the hill sphere, the of this planet doesn't extend far, at a distance of just 1.27 planetary radii. The, where the satellite takes the same time to orbit the planet as the rotation of the planet, analogous to the Earth's , is beyond the hill sphere at 13.21 planetary radii. If a satellite orbits at that distance, the orbit would be unstable which causes satellite to orbit in a. After some time, a satellite would eventually escape the planet's orbit into the orbit around the star. So Devana has no stable stationary orbit. If the orbit is stable, the orbital velocity at stationary orbit would be 3.31 km/s or 2.06 mi/s.

Interior
Like many s, Devana has the crust, mantle, and core. The crust is made out of carbon-rich rocks while mantle is made of molten rocks or. Its relatively low density for a rocky planet suggests that its core is small and made of in the form of  under the pressure of 3.28  heated to the temperature of 8500 K (8200°C, 14800°F). The size of the core is just the size of the planet. Because the planet is carbon-rich, Devana is speculatively a.

Surface
Since Devana is a terrestrial planet, it has a solid surface like Solar System planets, , , and. On its surface, there are terrains like hills, mountains, canyons, ridges, and plateaus. However, much of the surface are covered in molten lava because the planet is volcanically active due to influences of its nearby star, thus the intense heat would keep the surface molten for a long time. Because of this, craters are rare on Devana.

Volcanism
Since Devana is almost six times more massive than Earth and orbiting very close to the star, the tidal forces of the star would cause planet to stretch and squeeze constantly, causing friction, producing heat that would go on to melt rocks into magma. The magma melted by tidal forces causes intense on Devana with many es erupting all the time all over the surface. The tidal forces of the star exerted on Devana causing intense volcanism is analogous to the tidal forces of exerted on its moon, which causes Io to be the most volcanically-active world in our. So Devana would be the massive version of Io, known as "Super-Io." Perhaps, Devana would be even more volcanically-active world than Io since the tidal forces of the star is lot stronger than Jupiter. With the of 1129 K (856°C, 1572°F), which is hotter than Venus, it is hot enough for lava to cover much of the surface for long periods of time.

The only known example of a Super-Io is Icarus (, P311), discovered in early 2009 by, which spectroscopically revealed it to be a volcanically-active world.

Atmosphere
Since this is a low-mass planet orbiting very close to the star, Devana has very little atmosphere because the atmosphere is constantly stripping away by the radiation from the star. Devana has the atmospheric pressure of only 380 s, which is 266. times thinner than and 1.6 times thinner than.

Like and, Devana's atmosphere is made mostly of  (CO$2$), making up merely 96.8% of the atmosphere. All of the CO$2$ are given off by active volcanoes. Most of the remaining atmosphere is made of (N$2$), making up 89% of the remaining atmosphere. This atmosphere does contain small amounts of life-giving (O$2$) at 77  and  (H$st$O) at 33 ppm.

Even though volcanoes are constantly releasing (SO$th$) into the atmosphere, this gas would not concentrate since SO$rd$ would immediately decomposed by intense radiation from the nearby star, producing  that fall to the surface and  where it remains in the atmosphere.

Magnetic field
Devana has an extremely weak, about 30 millionths of a , which is 10,000 times weaker than.

Moons and rings
Because Devana orbits so close to its star and the small, Devana has no moons nor rings. But if moons actually exist, they have to orbit within 0. LD from the planet or they will flung off into space.

Future studies
It is speculated that Devana will not transit since I speculated that the is 58.7°. Studying Devana using the would not be a reliable option since the planet orbits way too close to the glare of its star. The planet can best be studied using using,  (JWST), or  (SIM). The astrometry can constrain the inclination and thus calculate the exact mass.

Maybe can reliably be used to directly image planets down to 0.01 AU from the sun-like stars. The direct imaging can see what Devana may really look like. The direct imaging can constrain the planet's size like the. The derivative parameters, including density and surface gravity, can then be calculated using the constrained radius and true mass calculated using inclination. Using the calculated density, astronomers can model the interior of this planet.

Astronomers may eventually use to study the interior, including the extent, features and compositions by layers. Using the mounted on the ATLAST, a tenuous atmosphere and the surface can be studied.

In orbit around the planet, moons and rings can be detected (if they exist) using the transit across the planet, detecting the wobble of the planet, or even direct imaging.

Related links

 * Tamar (61 Virginis c, P379)
 * Tuonetar (61 Virginis d, P380)