Discovery | |
---|---|
Discovered by | Marois et al. |
Discovery site | Keck and Gemini observatories in Hawaii |
Discovery date | November 13, 2008 |
Direct imaging | |
Orbital characteristics | |
~24 AU | |
Eccentricity | >0.04 [1] [note 1] |
~100 [2] [note 2] y | |
Star | HR 8799 |
Physical characteristics | |
1.2+0.1 −0 [2] RJ | |
Mass | 7+3 −2 [3] MJ |
Mean density | 5.978 g/cm3 [4] |
6.0+11.3 −2.5 h [5] | |
Equatorial rotation velocity | ~10.1+2.8 −2.7 km/s [5] |
Temperature | 1090+10 −90 [2] |
HR 8799 d is an extrasolar planet located approximately 129 light-years away in the constellation of Pegasus, orbiting the 6th magnitude Lambda Boötis star HR 8799. It has a mass between 5 and 10 Jupiter masses and a radius from 20 to 30% larger than Jupiter's. The planet orbits at 24 AU from HR 8799 with an eccentricity greater than 0.04 and a period of 100 years. Upon initial discovery, it was the innermost known planet in the HR 8799 system, but e , discovered later, is now known to be closer to their parent star. Along with two other planets orbiting HR 8799, this planet was discovered on November 13, 2008 by Marois et al., using the Keck and Gemini observatories in Hawaii. These planets were discovered using the direct imaging technique. [2] [6] [7] [8]
Near infrared spectroscopy from 995 to 1769 nanometers made with the Palomar Observatory show evidence of acetylene, methane, and carbon dioxide, but ammonia is not definitively detected. [9] In 2021, the further detection of water and carbon monoxide in the planetary atmosphere was made with the Keck Planet Imager and Characterizer (KPIC). [5]
HD 209458 is a star with an orbiting exoplanet in the constellation Pegasus. It has an apparent visual magnitude of 7.65 and an absolute magnitude of 4.28. Because it is located at a distance of 157 light-years from the Sun as measured via parallax, it is not visible to the unaided eye. With good binoculars or a small telescope it should be easily detectable. The system is drifting closer with a heliocentric radial velocity of −14.8 km/s.
2M1207b is a planetary-mass object orbiting the brown dwarf 2M1207, in the constellation Centaurus, approximately 170 light-years from Earth. It is one of the first candidate exoplanets to be directly observed. It was discovered in April 2004 by the Very Large Telescope (VLT) at the Paranal Observatory in Chile by a team from the European Southern Observatory led by Gaël Chauvin. It is believed to be from 5 to 6 times the mass of Jupiter and may orbit 2M1207 at a distance roughly as far from the brown dwarf as Pluto is from the Sun.
Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty of detecting such a faint light source, the light from the parent star causes a glare that washes it out. For those reasons, very few of the exoplanets reported as of January 2024 have been observed directly, with even fewer being resolved from their host star.
HD 24040 is a star with two orbiting exoplanets in the equatorial constellation of Taurus. The star is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.50. Based on parallax measurements, it is located at a distance of 152 light years. However, it is drifting closer to the Sun with a radial velocity of −9.4 km/s.
HD 40979 b is an extrasolar planet orbiting the star HD 40979, was detected from the Lick and Keck observatories and photometric observations at Fairborn Observatory reveal low-amplitude brightness variations in HD 40979. It is thought to be a large gas giant planet. It was discovered in 2002 by Debra Fischer.
HR 8799 is a roughly 30 million-year-old main-sequence star located 133.3 light-years away from Earth in the constellation of Pegasus. It has roughly 1.5 times the Sun's mass and 4.9 times its luminosity. It is part of a system that also contains a debris disk and at least four massive planets. Those planets, along with Fomalhaut b, were the first exoplanets whose orbital motion was confirmed by direct imaging. The star is a Gamma Doradus variable: its luminosity changes because of non-radial pulsations of its surface. The star is also classified as a Lambda Boötis star, which means its surface layers are depleted in iron peak elements. It is the only known star which is simultaneously a Gamma Doradus variable, a Lambda Boötis type, and a Vega-like star.
HR 8799 b is an extrasolar planet located approximately 129 light-years away in the constellation of Pegasus, orbiting the 6th magnitude Lambda Boötis star HR 8799. It has a mass between 4 and 7 Jupiter masses and a radius from 10 to 30% larger than Jupiter's. It orbits at 68 AU from HR 8799 with an unknown eccentricity and a period of 460 years, and is the outermost known planet in the HR 8799 system. Along with two other planets orbiting HR 8799, the planet was discovered on November 13, 2008 by Marois et al., using the Keck and Gemini observatories in Hawaii. These planets were discovered using the direct imaging technique.
HR 8799 c is an extrasolar planet located approximately 129 light-years away in the constellation of Pegasus, orbiting the 6th magnitude Lambda Boötis star HR 8799. This planet has a mass between 5 and 10 Jupiter masses and a radius from 20 to 30% larger than Jupiter's. It orbits at 38 AU from HR 8799 with an unknown eccentricity and a period of 190 years; it is the 2nd planet discovered in the HR 8799 system. Along with two other planets orbiting HR 8799, this planet was discovered on November 13, 2008, by Marois et al., using the Keck and the Gemini observatories in Hawaii. These planets were discovered using the direct imaging technique. In January 2010, HR 8799 c became the 3rd exoplanet to have a portion of its spectrum directly observed, confirming the feasibility of direct spectrographic studies of exoplanets.
HAT-P-11b is an extrasolar planet orbiting the star HAT-P-11. It was discovered by the HATNet Project team in 2009 using the transit method, and submitted for publication on 2 January 2009.
HD 179079 b is an extrasolar planet which orbits the G-type subgiant star HD 179079, located approximately 228 light years away in the constellation Aquila. This planet has mass only 1/12 that of Jupiter or 1.5 times Neptune. The planet orbits very close to the star, at a distance of 0.11 AU. This planet takes two weeks to revolve around the star. This planet was discovered using the Keck telescopes on August 12, 2009.
HD 4313 b is an extrasolar planet orbiting the K-type star HD 4313 approximately 447 light years away in the constellation Pisces. This planet was discovered using the Doppler spectroscopy method.
An exoplanet is a planet located outside the Solar System. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such until 2016; no planet discovery has yet come from that evidence. What turned out to be the first detection of an exoplanet was published among a list of possible candidates in 1988, though not confirmed until 2003. The first confirmed detection came in 1992, with the discovery of terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method. As of 24 July 2024, there are 7,026 confirmed exoplanets in 4,949 planetary systems, with 1007 systems having more than one planet. This is a list of the most notable discoveries.
HR 8799 e is a large exoplanet, orbiting the star HR 8799, which lies 129 light-years from Earth. This gas giant is between 5 and 10 times the mass of Jupiter. Due to their young age and high temperature all four discovered planets in the HR 8799 system are large, compared to all gas giants in the Solar System.
Benjamin Michael Zuckerman is an astrophysicist and an emeritus professor in the Department of Physics & Astronomy at UCLA. His recent work focus primarily on formation and evolution of planetary systems around various types of stars.
Kappa Andromedae b is a directly imaged substellar object and likely superjovian-mass planet orbiting Kappa Andromedae, a young B9IV star in the Andromeda constellation, about 170 light-years away. The companion's mass is roughly 13 times the mass of Jupiter. As early history on Kappa And b is filled with debate over whether it is an exoplanet or a brown dwarf, some scientists have broadly described it as a "super-Jupiter" object.
Project 1640 is a high contrast imaging project at Palomar Observatory. It seeks to image brown dwarfs and Jupiter-sized planets around nearby stars. Rebecca Oppenheimer, associate curator and chair of the Astrophysics Department at the American Museum of Natural History, is the principal investigator for the project.
GU Piscium b (GU Psc b) is a directly imaged planetary-mass companion orbiting the star GU Piscium, with an extremely large orbit of 2,000 AU (3.0×1011 km), and an apparent angular separation of 42 arc seconds. The planet is located at right ascension 01h 12m 36.48s declination +17° 04′ 31.8″ at a distance of 48 pc (160 ly).
Spectro-Polarimetric High-contrast Exoplanet REsearch (VLT-SPHERE) is an adaptive optics system and coronagraphic facility at the Very Large Telescope (VLT). It provides direct imaging as well as spectroscopic and polarimetric characterization of exoplanet systems. The instrument operates in the visible and near infrared, achieving exquisite image quality and contrast over a small field of view around bright targets.
BD+60 1417b is a confirmed exoplanet discovered in the year 2021 using the imaging method. BD+60 1417b is the only known exoplanet in the system BD+60 1417, around 45 parsecs from Earth. BD+60 1417 is a young K0 star, while BD+60 1417 b has a late-L spectral type. The planet might be the first discovery of a directly imaged exoplanet found by a citizen scientist. Discovery of exoplanets involving amateurs are usually transiting exoplanets and are rarely discovered with other methods. Another example of a non-transiting exoplanet discovery by an amateur is the microlensing exoplanet Kojima-1Lb.
Media related to HR 8799 d at Wikimedia Commons