Beta Pictoris b

Mass, radius and temperature Beta Pictoris b is a super-Jupiter, an exoplanet that has a radius and mass greater than that of the planet Jupiter. It has a temperature of , most likely due to its dusty atmosphere and mass (normally it would be much colder). It has a mass between 9 and 13 Jupiter masses (), and a radius of 1.46 . and has a surface temperature of 5778 K. It is slightly metal-rich, with a metallicity ([Fe/H]) of 0.06, or 112% of that found in the Sun. Its luminosity () is 8.7 times that of the Sun. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 3. Therefore, it can be seen with the naked eye. Orbit Beta Pictoris b orbits its host star every 21 years at a distance of 9.2 AU (about the same as Saturn's distance, which is about 9.55 AU). It receives 11% of the amount of sunlight that Earth does from the Sun. The orbit of the planet is well aligned to the rotation of the parent star and debris disk, with misalignment measured to be 3 degrees in 2020. Planetary rotation In 2014, the rotation period of Beta Pictoris b was calculated from the broadening of its carbon monoxide infrared absorption line. This makes it the first extrasolar planet to have its rotation rate measured. With a rotation period of 8.1 hours, it was the fastest-spinning exoplanet known as of 2014. Its rotation period is faster than that of Jupiter, which has a rotation period of around 10 hours. The rotation period was later refined to hours. ==Discovery==

The planet was discovered on November 18, 2008, by Anne-Marie Lagrange et al., using the NACO instrument on the Very Large Telescope at Cerro Paranal in northern Chile. This planet was discovered using the direct imaging technique, using reference star differential imaging. The discovery image was taken in 2003, but the planet was not detected when the data were first reduced. A re-reduction of the data in 2008 using modern image processing tools revealed the faint point source now known to be a planet. Further studies Follow-up observations performed in late 2009 and early 2010 using the same instrument recovered and confirmed the planet, but on the opposite side of the star. These findings were published in the journal Science and represented the closest orbiting planet to its star ever imaged. Observations performed in late 2010 and early 2011 allowed scientists to establish an inclination angle of the planet's orbit of 88.5 degrees, nearly edge-on. The location of the planet was found to be approximately 3.5 to 4 degrees tilted from the main disk in this system, indicating that the planet is aligned with the warped inner disk in the Beta Pictoris system. The first study of the spectral energy distribution of the planet was published in July 2013. This study shows detections at 1.265, 1.66, 2.18, 3.80, 4.05 and 4.78 μm demonstrating that the planet has a very dusty and/or cloudy atmosphere. The SED is consistent with that of an early L dwarf, but with a lower surface gravity. The effective temperature is constrained to and the surface gravity to log g = . A second study, published in September 2013, It may have been responsible for a transit-like event observed in 1981. In 2018, the PicSat cubesat was launched in a mission to image the planet Beta Pictoris b transiting its host star Beta Pictoris. As of 2025, the orbital parameters and mass of Beta Pictoris b have been measured using a combination of data from astrometry and imaging, showing that it has about 10.0 times the mass of Jupiter with a semi-major axis of about 10.0 AU. The orbital period is measured to be 23.59 years based on radial velocity, astrometry and direct imaging. == Potential exomoon ==

Beta Pictoris b has been found to have an obliquity likely misaligned by a 2024 study, based on a wide range of simulations together with published measurements. They find that the planet's obliquity must be misaligned if it spins fast, and might be if it spins slow. This misaligment could be caused by collisions with other planets, an unlikely scenario, or secular spin-orbit resonances modified by the presence of an exomoon. An exomoon with a mass similar to that of Neptune, an orbital separation of ( planetary radii) and an orbital period ranging from three to seven weeks (20 to 50 days) would induce the largest obliquities, up to 60°. Future observations by the James Webb Space Telescope will measure the planet's obliquity, something never done before in an extrasolar multiplanetary system. A detection of nonzero obliquity could be evidence of an exomoon. Currently the possibility of zero obliquity is unlikely. The use of astrometry does not rule out the exomoon candidate, but has set limits on the presence of exomoons. For short orbital periods (around 50 days), objects with masses over are ruled out, while at periods of roughly 200 days, this limit is . At orbital periods of 700 and 1,100 days, exomoons with masses over and , respectively, are ruled out. ==Gallery==

Stunning Exoplanet Time-lapse Beta Pictoris b.tif|Beta Pictoris b time-lapse. Beta_Pictoris_system_annotated.jpg|An annotated view of the Beta Pictoris system. Beta Pictoris b - The universal relation between mass and rotation speed of planets.jpg|Equatorial spin velocity vs mass for planets comparing Beta Pictoris b to the Solar System planets. Beta Pictoris star system.jpg|Artistic rendering of the Beta Pictoris system, showing the accretion disk, and the two planets. Beta Pictoris b.jpg|Artist's impression of Beta Pictoris b. The debris disk around the parent star can be seen. ==See also==