A proplyd, short for ionized protoplanetary disk, is an externally illuminated photoevaporating protoplanetary disk around a young star. Nearly 180 proplyds have been discovered in the Orion Nebula. Images of proplyds in other star-forming regions are rare, while Orion is the only region with a large known sample due to its relative proximity to Earth.
Comet Elst–Pizarro is a body that displays characteristics of both asteroids and comets, and is the prototype of active asteroids. Its orbit keeps it within the asteroid belt, yet it displayed a dust tail like a comet while near perihelion in 1996, 2001, and 2007.
Atira asteroids or Apohele asteroids, also known as interior-Earth objects (IEOs), are Near-Earth objects whose orbits are entirely confined within Earth's orbit; that is, their orbit has an aphelion smaller than Earth's perihelion, which is 0.983 astronomical units (AU). Atira asteroids are by far the least numerous group of near-Earth objects, compared to the more populous Aten, Apollo and Amor asteroids.
The Himalia group is a group of prograde irregular satellites of Jupiter that follow similar orbits to Himalia and are thought to have a common origin.
The Norse group is a large group of retrograde irregular satellites of Saturn. Their semi-major axes range between 12 and 27 Gm, their inclinations between 136° and 178° and their eccentricities between 0.06 and 0.63. Unlike the Inuit and Gallic groups, the orbital parameters are widely dispersed and the group is likely to be composed from a number of subgroups with more homogeneous orbital and physical parameters. The International Astronomical Union (IAU) reserves names taken from Norse mythology for these moons. The exception is Phoebe, the largest, which was discovered long before the others.
Epsilon Aquarii, Latinized from ε Aquarii, is a binary star in the equatorial zodiac constellation of Aquarius, located near the western constellation border with Capricornus. It has the proper name Albali, now formally recognized by the IAU. It is visible to the naked eye with an apparent visual magnitude of 3.77, and has an absolute magnitude of −0.46. Based upon parallax measurements taken by the Gaia spacecraft, it is located at a distance of approximately 244 light-years (75 pc) from Earth. The star is drifting closer with a radial velocity of −20 km/s.
Zeta Sagittarii is a triple star system and the third-brightest star in the constellation of Sagittarius after Kaus Australis and Nunki. Based upon parallax measurements, it is about 88 light-years from the Sun.
Gamma Aquilae, Latinized from γ Aquilae, and formally known as Tarazed, is a star in the constellation of Aquila. It has an apparent visual magnitude of 2.712, making it readily visible to the naked eye at night. Parallax measurements place it at a distance of 395 light-years from the Sun.
Active asteroids are small Solar System bodies that have asteroid-like orbits but show comet-like visual characteristics. That is, they show a coma, tail, or other visual evidence of mass-loss, but their orbits remain within Jupiter's orbit. These bodies were originally designated main-belt comets (MBCs) in 2006 by astronomers David Jewitt and Henry Hsieh, but this name implies they are necessarily icy in composition like a comet and that they only exist within the main-belt, whereas the growing population of active asteroids shows that this is not always the case.
The Lambda Orionis Cluster is an open star cluster located north-west of the star Betelgeuse in the constellation of Orion. It is about five million years old and roughly 1,300 ly (400 pc) away from the Sun. Included within the cluster is a double star named Meissa. With the rest of Orion, it is visible from the middle of August in the morning sky, to late April before Orion becomes too close to the Sun to be seen well. It can be seen from both the northern hemisphere and the southern hemisphere.
A quasi-Hilda comet (QHC) is a Jupiter-family comet that interacts strongly with Jupiter and undergoes extended temporary capture by it. These comets are associated with the Hilda asteroid zone in the 3:2 inner mean-motion resonance with Jupiter. Typically, asteroids in this zone have a semimajor axis between 3.70 and 4.20 AU, eccentricities below 0.30, and inclinations of no more than 20°. Comets can be temporarily perturbed into this group and then perturbed back out again. Eight percent of the comets that leave the 3:2 resonance end up impacting Jupiter.
An extreme trans-Neptunian object (ETNO) is a trans-Neptunian object orbiting the Sun well beyond Neptune (30 AU) in the outermost region of the Solar System. An ETNO has a large semi-major axis of at least 150–250 AU. The orbits of ETNOs are much less affected by the known giant planets than all other known trans-Neptunian objects. They may, however, be influenced by gravitational interactions with a hypothetical Planet Nine, shepherding these objects into similar types of orbits. The known ETNOs exhibit a highly statistically significant asymmetry between the distributions of object pairs with small ascending and descending nodal distances that might be indicative of a response to external perturbations.
Backyard Worlds: Planet 9 is a NASA-funded citizen science project which is part of the Zooniverse web portal. It aims to discover new brown dwarfs, faint objects that are less massive than stars, some of which might be among the nearest neighbors of the Solar System, and might conceivably detect the hypothesized Planet Nine. The project's principal investigator is Marc Kuchner, an astrophysicist at NASA's Goddard Space Flight Center.
Valetudo, also known as Jupiter LXII and originally known as S/2016 J 2, is an irregular moon of Jupiter. It was discovered by Scott S. Sheppard and his team in data acquired by the 6.5-m Magellan-Baade telescope of the Las Campanas Observatory in 2016, but was not announced until 17 July 2018, via a Minor Planet Electronic Circular from the Minor Planet Center, which also reported the discovery of nine other of Jupiter's moons. Besides data from Las Campanas, the original announcement also referred to data acquired through the 8.1-m Gemini North telescope of the Mauna Kea Observatories as well as the 4.0-m reflector of the Cerro Tololo Inter-American Observatory.
2I/Borisov, originally designated C/2019 Q4 (Borisov), is the first observed rogue comet and the second observed interstellar interloper after ʻOumuamua. It was discovered by the Crimean amateur astronomer and telescope maker Gennadiy Borisov on 29 August 2019 UTC.
In astronomy, a fast blue optical transient (FBOT), or more specifically, luminous fast blue optical transient (LFBOT), is an explosive transient event similar to supernovae and gamma-ray bursts with high optical luminosity, rapid evolution, and predominantly blue emission. The origins of such explosions are currently unclear, with events occurring at not more than 0.1% of the typical core-collapse supernova rate. This class of transients initially emerged from large sky surveys at cosmological distances, yet in recent years a small number have been discovered in the local Universe, most notably AT 2018cow.
C/2014 OG392 (PanSTARRS) is a comet discovered as a centaur on 28 July 2014 when it was 11.5 AU (1.72 billion km) from the Sun and had an apparent magnitude of 21. The comet was relatively easier to detect at this distance because the nucleus is estimated to be 20 km in diameter.
WISE 1534–1043 is a brown dwarf, Class Y, the coolest class, visible only in the infrared. It was accidentally discovered via the Wide-field Infrared Survey Explorer.
(248370) 2005 QN173 is a main belt asteroid that undergoes recurrent comet-like activity near perihelion, and is now designated comet 433P/(248370) 2005 QN173. This object was discovered on 29 August 2005 by the Near-Earth Asteroid Tracking program at Palomar Observatory. It orbits in the outer main asteroid belt with an orbital period of 5.36 years, a semi-major axis of 3.06 AU, and an orbital eccentricity of 0.225, bringing it as close as 2.37 AU to the Sun at perihelion. The orbital plane is inclined at an angle of 0.068° to the ecliptic.
2023 WK3 is a near-Earth object of the Atira group.
