A magnetar is a type of neutron star with an extremely powerful magnetic field (~109 to 1011 T, ~1013 to 1015 G). The magnetic-field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays.
Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters—about 15,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.
A supermassive black hole is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (M☉). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, including light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center. For example, the Milky Way galaxy has a supermassive black hole at its center, corresponding to the radio source Sagittarius A*. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei (AGNs) and quasars.
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.
Photoevaporation is the process where energetic radiation ionises gas and causes it to disperse away from the ionising source. The term is typically used in an astrophysical context where ultraviolet radiation from hot stars acts on clouds of material such as molecular clouds, protoplanetary disks, or planetary atmospheres.
Sagittarius A*, abbreviated as Sgr A*, is the supermassive black hole at the Galactic Center of the Milky Way. Viewed from Earth, it is located near the border of the constellations Sagittarius and Scorpius, about 5.6° south of the ecliptic, visually close to the Butterfly Cluster (M6) and Lambda Scorpii.
A pulsar is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth, and is responsible for the pulsed appearance of emission. Neutron stars are very dense and have short, regular rotational periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays.
First observed between August 4 and August 6, 1181, Chinese and Japanese astronomers recorded the supernova now known as SN 1181 in eight separate texts. One of only five supernovae in the Milky Way confidently identified in pre-telescopic records, it appeared in the constellation Cassiopeia and was visible and motionless against the fixed stars for 185 days. F. R. Stephenson first recognized that the 1181 AD "guest star" must be a supernova, because such a bright transient that lasts for 185 days and does not move in the sky can only be a galactic supernova.
The Milky Way has several smaller galaxies gravitationally bound to it, as part of the Milky Way subgroup, which is part of the local galaxy cluster, the Local Group.
Sagittarius B2 is a giant molecular cloud of gas and dust that is located about 120 parsecs (390 ly) from the center of the Milky Way. This complex is the largest molecular cloud in the vicinity of the core and one of the largest in the galaxy, spanning a region about 45 parsecs (150 ly) across. The total mass of Sgr B2 is about 3 million times the mass of the Sun. The mean hydrogen density within the cloud is 3000 atoms per cm3, which is about 20–40 times denser than a typical molecular cloud.
In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of galactic superclusters. These massive, thread-like formations can commonly reach 50/h to 80/h megaparsecs —with the largest found to date being the Hercules-Corona Borealis Great Wall at around 3 gigaparsecs (9.8 Gly) in length—and form the boundaries between voids. Due to the accelerating expansion of the universe, the individual clusters of gravitationally bound galaxies that make up galaxy filaments are moving away from each other at an accelerated rate; in the far future they will dissolve.
The Event Horizon Telescope (EHT) is a telescope array consisting of a global network of radio telescopes. The EHT project combines data from several very-long-baseline interferometry (VLBI) stations around Earth, which form a combined array with an angular resolution sufficient to observe objects the size of a supermassive black hole's event horizon. The project's observational targets include the two black holes with the largest angular diameter as observed from Earth: the black hole at the center of the supergiant elliptical galaxy Messier 87, and Sagittarius A*, at the center of the Milky Way.
The Central Molecular Zone or CMZ is a region of the Milky Way Galaxy rich in an estimated 60 million solar masses (M☉) of gas within a complex of giant molecular clouds. It spans the centre of the Milky Way, and as such is in the Sagittarius constellation, between galactic longitude 1.7° and -0.7°, and latitudes -0.2° and +0.2°.
1E1740.7-2942, or the Great Annihilator, is a Milky Way microquasar, located near the Galactic Center on the sky. It likely consists of a black hole and a companion star. It is one of the brightest X-ray sources in the region around the Galactic Center.
SGR J1745−2900, or PSR J1745−2900, is the first-discovered magnetar orbiting the black hole Sagittarius A*, in the center of the Milky Way. The magnetar was discovered in 2013 using the Effelsberg 100-m Radio Telescope, the Nancay Decimetric Radio Telescope, and the Jodrell Bank Lovell Telescope. The magnetar has a period of 3.76 s and a magnetic flux density of ~ 1010 T (1014 G). The magnetar is 0.33 ly from the central black hole.
Naomi McClure-Griffiths is an American-born Australian astrophysicist and radio astronomer. In 2004, she discovered a new spiral arm in the Milky Way galaxy. She was awarded the Prime Minister's Malcolm McIntosh Prize for Physical Scientist in 2006 and in 2015 was honored for her research in physics by receipt of the Pawsey Medal from the Australian Academy of Science. This was followed by an Australian Laureate Fellowship in 2021, while in 2022 she was elected a Fellow of the Australian Academy of Science.
TON 618 is a hyperluminous, broad-absorption-line, radio-loud quasar, and Lyman-alpha blob located near the border of the constellations Canes Venatici and Coma Berenices, with the projected comoving distance of approximately 18.2 billion light-years from Earth. It possesses one of the most massive black holes ever found, at 40.7 billion M☉.
Imaging X-ray Polarimetry Explorer, commonly known as IXPE or SMEX-14, is a space observatory with three identical telescopes designed to measure the polarization of cosmic X-rays of black holes, neutron stars, and pulsars. The observatory, which was launched on 9 December 2021, is an international collaboration between NASA and the Italian Space Agency (ASI). It is part of NASA's Explorers program, which designs low-cost spacecraft to study heliophysics and astrophysics.
Robert Michael Rich is an American astrophysicist. He obtained his B.A. at Pomona College in 1979 and earned his Ph.D. from the California Institute of Technology in 1986 under thesis supervisor Jeremy Mould. He was a Carnegie Fellow at Carnegie/DTM until 1988, when he became an assistant professor of astronomy at Columbia University; during this period, he was the doctoral advisor to Neil deGrasse Tyson. After two years (1996-1998) as a senior research scientist at Columbia, he joined the University of California, Los Angeles as a research astronomer in 1998. As of 2024, he remains affiliated with UCLA as a researcher emeritus/adjunct professor emeritus of astronomy and astrophysics.
Little red dots (LRDs) are a class of small, red-tinted galaxies discovered by the James Webb Space Telescope. Their discovery was published in March 2024, and they are currently poorly understood. They appear to have existed between 0.6 and 1.6 billion years after the Big Bang, from 13.2 to 12.2 billion years ago.
