This is what Cerenytis may look like assuming its mass is minimum and temperature at its equilibrium
Date July 6, 1998
Discoverers Naef et al.
Detection method Radial velocity
Site Geneva Observatory
Name & designations
Pronunciation /'sir•en•i•tis/
Adjective Cerenytian
Planet numbers P20, 14 Herculis P1,
Hercules P1, Tarandus P1,
1998 P2, 1998 Her-1,
1998 Tar-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
System 14 Herculis
Constellation Hercules
Caelregio Tarandus
Right ascension 16h 10m 24.31s (242.601 31°)
Declination +43° 49' 03.5" (+43.817 64°)
Distance 17.570 pc (57.307 ly)
Orbital characteristics
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
Bulk characteristics
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
Density 37.745 g/cm³
Gravitational influence
Surface gravity 56.499 g (554.07 m/s²)
Weight on Cerenytis
(150 lb on Earth)
8 475 lb
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 characteristics
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
Axial tilt 107.857°
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
Thermal characteristics
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
Dipole tilt 4.16°
Satellite system
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.

Cerenytis is named after the deer in Greek mythology.

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

Orbit 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.

Rotation Edit

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 34 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 313 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 27 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 5612 times stronger than Earth's. So if you weigh 150 pounds on Earth, you would weigh 8475 pounds 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.

Interior Edit

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.

Atmosphere Edit

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

This planet has an ultra-strong magnetic field, about 14.78 gauss, which is 48 times stronger than Earth's.

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.

Cerenytis has only one ring. Just 100 million years ago, Cerenytis had an extensive ring system like Saturn's.

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.

Related links Edit