Deino

Deino (HD 11964 b, P153) is a which orbits the yellow   , meaning the star has just ran out of hydrogen fuel in its core. The star is considerably larger but cooler and lot more luminous than our, located 107 s or 33 s from towards the   in the caelregio Hippocampus.

Deino is four times more massive than Jupiter, but similar in size. It orbits a bit closer to the star than Jupiter with an orbital period of 64 months (5. years).

(the dread) is named after one of the sisters in in.

Discovery and chronology
Deino was discovered on August 7, 2005 by a team of astronomers led by. The team used the mounted on the telescope in  and found that this star wobble caused by planets. On that same day, the second planet Scylla was also announced. However, Deino wasn't fully confirmed until May 27, 2007.

Deino is the 146$J$ exoplanet discovered overall, 120$J$ since 2000, and 25$J$ in 2005. Deino is also the 5$J$ exoplanet discovered in the constellation Cetus (3$J$ in 2005) and 20$J$ exoplanet discovered in the caelregio Hippocampus (5$⊕$ in 2005). Deino is the second planet discovered in the HD 11964 system, despite its designation HD 11964 b (a is not used because the parent star uses this letter to reduce confusion). More accurately, this planet is also designated HD 11964 P2. However, at the time of its discovery, this planet was designated HD 11964 c. 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
Deino takes 168 s (5.33 s) to orbit eccentrically around the star at an of 15.38 microparsecs (3.172 s). During one point of its orbit, Deino can be as close to the star as 14.75 μpc (3.043 AU) or as far away as 16.00 μpc (3.301 AU). The planet moves at an of 17.80 km/s and it varies from 17.43 to 18.15 km/s during its orbit. It's speculated is 9° to  (1.55° to star's ). The is 102°, which is the angle between periastron and. The is 253° counterclockwise from the  at  as seen from north. Adding argument of periastron and longitude of ascensing node yields 408° in, but since it is more than 360°, we subtract that number and finished with 48°.

Parent star observation and irradiance
When viewing HD 11964 from one of its moons since this planet is a with no solid surface, that sun would appear to be four times dimmer than the Sun as seen from Earth, corresponding to its  −25.23. The of HD 11964 as seen from Deino is 0.163°, which is one-third the angular diameter of the full moon and sun as seen from Earth, because Deino orbits nearly 3.2 times farther away from the star than Earth to the Sun.

Deino receives an average of 106 W/m² of compared to 1368 W/m² for Earth and 51 W/m² for Jupiter.

Rotation
Deino takes 7 hours, 26 minutes, and 38 seconds to rotate once on its axis, which is nearly one-third of an Earth day. The is 16.36 km/s, 10.17 mi/s, 58902 kph, or 36600 mph. This planet rotates in the same direction as its revolution. Deinian year lasts 6255 Deinian days, compared to Earth year that lasts 366 Earth days. The tilt of this planet is such that its points to the Earth's northern equatorial constellation  (in Felis), while the  points to the Earth's southern equatorial constellation  (in Hippocampus).

Mass and size
Using the speculated inclination, its speculated for Deino is 3.8125  or 1211.7. This planet had a 0.6059 M$2$ or 192.6 M$2$. It is classified as super-Jupiter in the planetary mass classification scheme. This planet has mean radius of 67.520 megameters, which is slightly smaller than Jupiter. Deino has density 5.432 g/cm³, which is slightly less dense than Earth. Its is 0.0218, one-third that of 's.

Gravitational influence
Deino has gravitational force 10 times stronger than Earth's and four times that of Jupiter's. The object falling to the planet accelerates at 103 m/s² or 340 ft/s². If you weigh 150 on Earth, you would weigh 1583 pounds on Deino.

The, where a 3 g/cm³ moon tear apart by tidal forces, is 0.273 s (105 s), which is 1.54 planetary radii. The, the boundary where the gravitational influence of the planet is identical to the star, is 126.28 lunar distances (48.54 gigameters), which is 711 times the radius of the planet. The, where the satellite's orbital period is identical to the rotation period of the planet, analogous to the Earth's , is 137.8 Mm, which is 2.00 planetary radii and one-third the Earth-Moon distance. The stationary velocity, the orbital velocity at stationary orbit, is 48.4 km/s or 30.1 mi/s. Since the planet takes 7. hours to rotate, then a moon would take 7. hours to orbit the planet at stationary orbit.

Interior
Below Deino's outer envelope (atmosphere), the weight of all the gases pressing down produce a tremendous pressure. That pressure allow and  to condense in the upper mantle despite the higher temperatures deeper down. In the middle mantle lies liquid where hydrogen can conduct electricity under even greater pressure heated beyond its. In the middle mantle, the temperature is 34,000 K (33,800°C, 60,800°F) and a pressure 820. In the lower mantle, there is a narrow layer of solid metallic hydrogen at a pressure of 2.2 and temperature 40,800 K (40,500°C, 73,000°F). At the center lies a core of rock and metal with a mass 23 Earth masses, roughly 1.9% the total mass of the planet. The temperature of the core is estimated to be 43,300 K (43,000°C, 77,400°F) and an estimated pressure 6.7 TPa.

Atmosphere
Deino's atmosphere composes about 92.7% and 5.5%, along with trace amounts of other gases, including  and  but no. The atmosphere also contains small amounts of (rotten egg gas) at 697.

Deino contains water clouds and the planet appears light gray from space. The water clouds are in the cooler upper deck and sulfur clouds in the warmer lower deck. Heat from its interior raises the temperature from 135 K (−138°C or −217°F) to 370 K (97°C or 206°F). This planet radiates about same amount of heat as it receives from the star, because the star is over four times more luminous than our Sun, plus the planet orbits 61% closer to HD 11964 than Jupiter to the Sun. Like Jupiter, there are hundreds of s and s, which can produce storms and high winds.

Magnetic field
This planet has a very strong, at around 11.54. It is 2.65 times more powerful than and 37.46 times more powerful than. Because of the very strong magnetic field, Deino can have frequent and vivid s when the stellar activity is high or from nearby moons.

Moons and rings
Deino has 74 and it has 20 dusty. The largest moon has mass 12.1 Lunar masses (0.149 Earth masses) and has diameter 1.911 Lunar diameters (4,125 miles, 6,638 kilometers), which is more massive and about the size of. There are five other moons that are bigger than our, six with diameters between 1000 miles and the diameter of our Moon, and 22 have diameters between 100 and 1000 miles. All the rest (40) are less than 100 miles in diameter.

Future studies
The method will use to study Deino might be using the space telescopes like the  (JWST) to see what this planet actually looks like. The speculated inclination is 171°, which is almost face-on, which of course does not allow transits. The inclination of Deino's orbit shall be constrained using from,  (JWST), or  (SIM). However, the inclination could be constrained sooner using the ground-based telescopes or the (HST) guidance sensor. Determining the inclination is important for determining its actual mass.

The direct imaging can constrain the size of this planet. After knowing its size, density and surface gravity can then be calculated. Using the density of the planet, astronomers can probe the interior and estimate the mass and size of the core. Astronomers will also study the mantle and its temperature of the core using. Using the spectrometer mounted on the JWST, it can constrain its temperature and study the atmospheric chemical makeup. Using the same method, the rotation rate can also be constrained using s. Using the rotation rate and circumference of the planet (calculated using 2π radius), can then be calculated. In orbit around the planet, moons can be detected using the transit across the planet, detecting the wobble of the planet, or even direct imaging. Rings can also be detected using just two methods: transit or direct imaging.

Deino can further be studied using the JWST's successor: (due to launch between 2025–35).

Related links

 * Scylla (HD 11964 c, P152)