|Date||July 6, 1998|
|Discoverers||Naef et al.|
|Detection method||Radial velocity|
|Name & designations|
|Planet numbers|| P20, 14 Herculis P1,|
Hercules P1, Tarandus P1,
1998 P2, 1998 Her-1,
|Star designations|| 14 Herculis b, 11 Tarandi b,|
BF 2110 b, PH 11 b,
P1 Herculis b, P1 Tarandi b,
HD 145675 b, HIP 79248 b,
Gliese 614 b, SAO 45933 b
|Right ascension||16h 10m 24.31s (242.601 31°)|
|Declination||+43° 49' 03.5" (+43.817 64°)|
|Distance||17.570 pc (57.307 ly)|
|Semimajor axis||2.769 963 AU (414.380 6 Gm)|
|Periastron||1.834 352 AU (274.415 2 Gm)|
|Apastron||3.705 574 AU (554.345 9 Gm)|
|Eccentricity||0.337 770 1|
|Orbital circumference||17.030 60 AU (2 547.742 Gm)|
|Orbital area||22.687 83 AU² (507 742.79 Gm²)|
|Orbital period||1 773.400 546 d (4.855 306 08 yr)|
|Avg. velocity||16.684 km/s (3.508 AU/yr)|
|Max. velocity||19.297 km/s (4.057 AU/yr)|
|Min. velocity||13.577 km/s (2.854 AU/yr)|
| Direction of orbit|
relative to star's rotation
|Inclination|| 24.750° to ecliptic|
−4.244° to star's equator
4.105° to invariable plane
|Argument of periastron||22.556°|
|Longitude of ascending node||188.579°|
|Longitude of periastron||211.134°|
|Angular separation||157.650 mas|
|Observing the parent star|
|Mean angular star size||0.173 05° (10.383')|
|Max. angular star size||0.261 32° (15.679')|
|Min. angular star size||0.129 36° (7.762')|
|Mean star magnitude||−23.914|
|Max. star magnitude||−24.809|
|Min. star magnitude||−23.283|
|Mean radius||0.752 00 RJ (52.597 Mm)|
|Equatorial radius||0.736 97 EJ (52. 660 Mm)|
|Polar radius||0.784 10 PJ (52.470 Mm)|
|Mean circumference||330.475 Mm|
|Equatorial circumference||330.872 Mm|
|Polar circumference||329.681 Mm|
|Surface area||0.566 04 SJ (34 764 Mm²)|
|Volume||0.425 86 VJ (6.094 9 × 105 Mm³)|
|Flattening||0.003 60 (1:277.5)|
|Angular diameter||40.021 μas|
|Mass||12.115 595 MJ|
| Reciprocal mass|
relative to star
|Surface gravity||56.499 g (554.07 m/s²)|
| Weight on Cerenytis|
(150 lb (1 wa) on Earth)
|8 475 lb (56.50 wa)|
|Standard gravitational parameter||1.535 × 109 km³/s²|
|Escape velocity||241.59 km/s|
|Hill radius||120.512 LD (46.324 6 Gm)|
| Roche limit|
(3 g/cm3 satellite)
|0.400 96 LD (154.128 Mm)|
|Stationary orbit||0.743 34 LD (285.740 Mm)|
|Stationary velocity||67.457 km/s (15.162 LD/d)|
|Rotation period||8.755 5 h (0.364 813 d)|
|Rotation velocity||10.497 km/s (41.12°/h)|
| Direction of rotation|
relative to orbit
|Longitude of vernal equinox||311.066°|
|North pole right ascension||19h 55m 07s (298.779°)|
|North pole declination||+25° 00' 32" (+25.009°)|
|North polar constellation||Vulpecula|
|North polar caelregio||Testudo|
|South pole right ascension||07h 55m 07s (118.779°)|
|South pole declination||−25° 00' 32" (−25.009°)|
|South polar constellation||Puppis|
|South polar caelregio||Malus|
|Surface temperature||793 K (520°C, 967°F, 1427°R)|
|Mean irradiance||102 W/m² (0.0746 I⊕)|
|Irradiance at periastron||233 W/m² (0.170 I⊕)|
|Irradiance at apastron||57.0 W/m² (0.0417 I⊕)|
|Albedo||0.163 (bond), 0.187 (geom.)|
|Scale height||5.10 km|
|Surface density||0.410 g/m³|
|Molar mass||2.27 g/mol|
|Composition|| 90.746% hydrogen (H2)|
8.756% helium (He)
0.435% methane (CH4)
237 ppm water (H2O)
67.5 ppm hydrogen deuteride (HD)
332 ppb hydrogen sulfide (H2S)
261 ppb phosphine (PH3)
41.1 ppb neon (Ne)
782 ppt propane (C3H8)
232 ppt krypton (Kr)
7.41 ppt benzene (C6H6)
|Dipole strength||1.48 mT (14.8 G)|
|Magnetic moment||8.71 × 1021 T•m³|
|Number of moons||203|
|Number of rings||1|
Cerenytis (14 Herculis b, P20) is an exoplanet which orbits the yellow-orange K-type main sequence star 14 Herculis, meaning the star is smaller, cooler and thus dimmer than our Sun. It is approximately 57 light-years or 18 parsecs from Earth towards the constellation Hercules in the caelregio Tarandus.
Cerenytis orbits at a same distance from the star as the inner asteroid belt of our solar system, nearly two times closer to the star than Jupiter is to the Sun. However, this planet is far more massive and denser than Jupiter.
Discovery and chronology Edit
Cerenytis was discovered on July 6, 1998 by a team of astronomers led by Dominic Naef. The team used the spectrometer mounted on the telescope in Geneva Observatory in Switzerland and found that this star wobble caused by an orbiting planet. Seven years later, more continuous observations revealed the evidence of a second planet Eurystheus.
Cerenytis is the 13th exoplanet discovered overall and 2nd exoplanet discovered in 1998. Cerenytis is also the 1st exoplanet discovered in the constellation Hercules and 1st in the caelregio Tarandus. Since Cerenytis is the first planet discovered in the 14 Herculis system, the planet receives the designations 14 Herculis b (a is not used because the parent star uses this letter to reduce confusion) and 14 Herculis P1. Note that the chronology does not include speculative brown dwarfs (objects with minimum masses below 13 MJ but with speculative true masses above 13 MJ).
Orbit and rotation Edit
Cerenytis is located in the inner region of the Alphian orbit at an average distance of 2.77 AU (1 AU is the average distance between the Earth and the Sun) from 14 Herculis. This corresponds that light from its parent star takes 2.77 times longer than light from our Sun to reach our homeworld. If we place this planet in our solar system, it would orbit the same distance from the sun as 2 Pallas in the asteroid belt between the orbits of Mars and Jupiter. However, Cerenytis orbits in an eccentric path. Cerenytis can sometimes be as close as 1.83 AU or as distant as 3.71 AU from the star. The planet takes 4.86 years or over 58 months to make one complete trip around the star at an average velocity of 3.51 AU/yr or 16.7 km/s. Cerenytis is in a 1:4 resonance with the outer planet Eurystheus.
Parent star observation and irradiance Edit
Viewed from Cerenytis, the parent star would appear to be 13½ times fainter than the Sun seen from Earth on average. The parent star has a magnitude −23.91 compared to −26.74 for the Sun's magnitude viewed from Earth. However because the planet orbits in an eccentric path, the brightness of the star appears to vary by a factor of four from −23.28 to −24.81. Viewed from Cerenytis, the parent star would have an angular diameter of 10.4' on average, which is ⅓ the angular diameter of the full moon we see every month. However, the angular diameter of the star appears to vary from 7.8' to 15.7' throughout its orbit.
Cerenytis receives 0.075 I⊕ of energy from its star, or about 100 watts per square meter.
Cerenytis rotates very rapidly, even more rapid than the fastest rotator in the solar system, Jupiter. It takes just 8¾ hours to make one complete turn. A year on Cerenytis lasts 4861 Cerenytis days, which is 13.27 times longer than a year on Earth. Even more stranger is that the planet rotates in the opposite direction as its orbit plus it is rotating on its side. The planet tilts 107.9° to the plane of its orbit, which is almost perpendicular to the orbital plane. The planet's north pole points to the constellation Vulpecula (in Testudo), while the south pole points to the constellation Puppis (in Malus).
Structure and composition Edit
Mass and size Edit
Cerenytis is extremely massive, more than 12 times more massive than Jupiter, the most massive planet in our solar system. It is classified as super-Jupiter in the planetary mass classification scheme. Even though this planet is much more massive than Jupiter, it is only 3⁄4 the size of Jupiter, meaning that Cerenytis must be very dense, has very strong gravity, and has very high escape velocity. Even though Cerenytis is 31⁄3 times denser than Earth (18.6 vs. 5.5 g/cm³), the densest planet in our solar system, it would still be a gas giant with no solid surface.
Despite the planet rotates faster than Jupiter, its flattening is just 2⁄7 that of Jupiter's, because of its tremendous gravitational pull. Its equatorial diameter is 2,440 km wider than its polar diameter. Its equatorial circumference is 420,923 km while its polar circumference is 413,258 km, a difference of 7,665 km.
Gravitational influence Edit
The gravitational force of Cerenytis is 561⁄2 times stronger than Earth's. So if you weigh 150 pounds (1 wame) on Earth, you would weigh 8475 pounds (56.50 wames) or 4.237 tons on Cerenytis. So a person standing on Cerenytis would weigh nearly as much as a large pickup truck parked on Earth! The minimum speed needed to escape the planet is merely 241.59 km/s, 21.6 times higher than the speed needed to escape Earth and 4.1 times higher than the speed needed to escape Jupiter.
Since the gravity of this planet is so strong, a 3 g/cm³ moon would be torn apart if it orbits within 0.4 lunar distances or 2.9 times the radius of the planet, which is pretty far. The radius of the hill sphere is 121 lunar distances or 696 times the radius of the planet. The orbit where the satellite's orbital period is identical to rotation period of the planet, analogous to the Earth's geostationary orbit, is 0.74 LD or 5.4 planetary radii, just 75% further out than roche limit. The stationary velocity is calculated to be 67.5 km/s or 41.9 mi/s. Since the planet takes 8¾ hours to rotate, then a moon would also take 8¾ hours to orbit the planet at stationary orbit.
Below Cerenytis' outer envelope (atmosphere), the weight of all the gases pressing down produce a tremendous pressure. That pressure allow hydrogen and helium to condense in the upper mantle despite the higher temperatures deeper down. In the middle mantle lies liquid metallic hydrogen where hydrogen can conduct electricity under even greater pressure heated beyond its critical point. In the lower mantle, there is narrow layer of solid metallic hydrogen. In the outer core, it lies solid metallic deuterium where ultra-intense magnetic fields are produced. At the center lies an ultra-dense core of rock and metal with a mass 371 Earth masses, roughly 9.6% the total mass of the planet. The temperature of the core is estimated to be 178,900 K (178,600°C, 321,400°F) and an estimated pressure 9.46 TPa.
Like all gas giants, Cerenytis' atmosphere composes mostly of hydrogen with helium making up most of the rest. Cerenytis contains trace amounts of methane and water vapor making up most of the remaining. The atmosphere contains tiny amounts of propane instead of ethane, making up less than one-billionth of the atmosphere.
Cerenytis contains banded clouds of ammonia and water and this planet appears orange and white stripes from space. The ammonia clouds are in the cooler upper deck and water clouds in the warmer lower deck. The equilibrium temperature, based on its orbital distance and luminosity of the star, is 133 K (−140°C, −220°F), which is right for the formation of ammonia gas clouds. However with so much internal heating because the planet is more than 12 times more massive than Jupiter, the actual temperature of Cerenytis is 793 K (520°C, 967°F), which would render this giant planet cloud free. This planet radiates ten times the amount of energy than it receives from the parent star. There are thousands of jet streams and zonal jets, which can produce violent long-lasting storms and high winds, even more violent than Jupiter's.
Magnetic field Edit
That powerful magnetic field is produced by the movements of metallic hydrogen in its interior caused by the planet's rotation. This mechanism is well known as dynamo effect. The magnetic field blocks most of stellar and cosmic radiation from reaching the planet, but occasionally it can produce beautiful, vivid aurorae more brilliant than we see on Earth when the stellar radiation got caught in the magnetic field lines and move towards their poles where it interact with the planet's upper atmosphere (ionosphere). Its magnetic field is so strong that occasional auroral display are often more brilliant than aurorae on Earth.
Moons and rings Edit
Cerenytis has a huge family of 203 moons, including a lot of moons larger than our Moon and one larger than Earth. The largest moon has mass 134.7 Lunar masses (1.657 Earth masses) and has diameter 4.519 DL (9,755 miles, 15,698 kilometers). There are roughly 19 moons bigger than our Moon and four of these are larger than Mars. 13 moons have diameters between 1000 miles and 2000 miles, 33 have diameters between 100 and 1000 miles and 144 have diameters less than 100 miles.
Future studies Edit
The probability that Cerenytis will transit 14 Herculis can be a slim 0.42% chance, but it is speculated that Cerenytis will not transit since I speculated that the inclination is 25°. Cerenytis can be studied effectively using astrometry or direct imaging. The planet can be studied using astrometry using Gaia, James Webb Space Telescope (JWST), Space Interoferometry Mission (SIM), or even the current Hubble Space Telescope (HST) guidance sensor. The astrometry can constrain the inclination and thus calculate the exact mass. The direct imaging can see what the planet may really look like. The direct imaging can constrain the size of this planet like transit method. The derivative parameters, including density and surface gravity, can then be calculated using the radius constrained from direct imaging and true mass calculated by inclination. Using the calculated density, astronomers can model the interior of this planet.
Astronomers may eventually use astroseismology to study the interior, including the extent, features and compositions by layers. Using the spectrometer mounted on the JWST, the atmosphere can be studied, including temperatures, chemical makeup, and features. Using the same method, the rotation rate can be constrained using Doppler shifts, which in turn rotation period 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.
Cerenytis can further be studied using the JWST's successor: ATLAST, due to launch between 2025–35.
- Eurystheus (14 Herculis c, P163)