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Topic Review
Equuleus
Equuleus, Latin for "the little horse," is one of the 88 modern constellations recognized by the International Astronomical Union. Despite its small size and dim stars, Equuleus holds historical significance, dating back to ancient times when it was known as a separate constellation or asterism. Today, it remains a subtle yet intriguing feature of the night sky, nestled between the larger constellations of Pegasus and Delphinus.
  • 1.0K
  • 15 Mar 2024
Topic Review
Soyuz T-15
Soyuz T-15 (Russian: Союз T-15, Union T-15) was a crewed mission to the Mir and Salyut 7 space stations and was part of the Soyuz programme. It marked the final flight of the Soyuz-T spacecraft, the third generation Soyuz spacecraft, which had been in service for seven years from 1979 to 1986. This mission marked the first time that a spacecraft visited, and docked with, two space stations in the same mission.
  • 1.0K
  • 17 Oct 2022
Topic Review
ASTER (Spacecraft)
ASTER is a planned space mission under development by the Brazilian Space Agency that will launch a spacecraft to orbit a near-Earth object known as (153591) 2001 SN263, a triple asteroid system. The launch is scheduled for 2025, with a rendezvous in 2024/2027. According to de Brum et al. 2021, the launch is planned for June 2022 (asteroid arrival in December 2024) or June 2025 (arrival September 2027).
  • 1.0K
  • 15 Nov 2022
Topic Review
Chamaeleon
Chamaeleon, a small and inconspicuous constellation in the southern celestial hemisphere, represents the chameleon, a creature known for its ability to change color and blend into its surroundings. Despite its modest size, Chamaeleon holds significance in astronomy for its proximity to the southern celestial pole and its role in studying star formation and stellar evolution.
  • 995
  • 08 Mar 2024
Topic Review
GEO600
GEO600 is a gravitational wave detector located near Sarstedt in the South of Hanover, Germany. It is designed and operated by scientists from the Max Planck Institute for Gravitational Physics, Max Planck Institute of Quantum Optics and the Leibniz Universität Hannover, along with University of Glasgow, University of Birmingham and Cardiff University in the United Kingdom, and is funded by the Max Planck Society and the Science and Technology Facilities Council (STFC). GEO600 is part of a worldwide network of gravitational wave detectors. This instrument, and its sister interferometric detectors, when operational, are some of the most sensitive gravitational wave detectors ever designed. They are designed to detect relative changes in distance of the order of 10−21, about the size of a single atom compared to the distance from the Sun to the Earth. GEO600 is capable of detecting gravitational waves in the frequency range 50 Hz to 1.5 kHz. Construction on the project began in 1995.
  • 989
  • 03 Nov 2022
Topic Review
Current Status of The Celestial Reference Frame
The International Celestial Reference Frame (ICRF) is based on the currently accepted International Celestial Reference System (ICRS) and forms the basis for all positional astronomy in the radio domain. The first three generations of this frame have been built from high precision Very Long Baseline Interferometry (VLBI) astrometric measurements of positions of extragalactic radio sources (quasars and other radio-loud Active Galactic Nuclei, AGN), with each successive realization of the ICRF becoming more precise. VLBI angular position accuracy has now improved to near the 100 micro-arcsecond (μas) level. Catalogues of positions of extragalactic radio sources with the highest precision, such as the ICRF, are crucial to many applications, such as determining the Earth’s orientation in space, providing calibrator sources for astronomy, studying the motion of tectonic plates, and in spacecraft navigation. The ICRF also contributes towards the realization of a Global Geodetic Reference Frame (GGRF) for sustainable development, a resolution adopted by the United Nations in 2015.
  • 960
  • 28 Jul 2022
Topic Review
Odd Radio Circles and Their Environment
Odd Radio Circles (ORCs) are unexpected faint circles of diffuse radio emission discovered in recent wide deep radio surveys. They are typically about one arcmin in diameter, and may be spherical shells of synchrotron emission about a million light years in diameter, surrounding galaxies at a redshift of ∼0.2–0.6. Here we study the properties and environment of the known ORCs.
  • 945
  • 17 Nov 2021
Topic Review
AT2018cow
Coordinates: 16h 16m 00.2242 s, +22° 16′ 04.890 ″ AT2018cow (ATLAS name: ATLAS18qqn; also known as Supernova 2018cow, SN 2018cow, and "The Cow") was a very powerful astronomical explosion, 10 – 100 times brighter than a normal supernova, spatially coincident with galaxy CGCG 137-068, approximately 200 million ly (60 million pc) distant in the Hercules constellation. It was first detected on 16 June 2018 by the ATLAS-HKO telescope, and had generated significant interest among astronomers throughout the world. Later, on 10 July 2018, and after AT2018cow had significantly faded, astronomers, based on followup studies with the Nordic Optical Telescope (NOT), formally described AT2018cow as SN 2018cow, a type Ib supernova, showing an "unprecedented spectrum for a supernova of this class"; although others, mostly at first but also more recently, have referred to it as a type Ic-BL supernova. An explanation to help better understand the unique features of AT2018cow has been presented.
  • 941
  • 19 Oct 2022
Topic Review
PSR J1614–2230
PSR J1614–2230 is a neutron star in a binary system with a white dwarf. It was discovered in 2006 with the Parkes telescope in a survey of unidentified gamma ray sources in the Energetic Gamma Ray Experiment Telescope catalog. PSR J1614–2230 is a millisecond pulsar, a type of neutron star, that spins on its axis roughly 317 times per second, corresponding to a period of 3.15 milliseconds. Like all pulsars, it emits radiation in a beam, similar to a lighthouse. Emission from PSR J1614–2230 is observed as pulses at the spin period of PSR J1614–2230. The pulsed nature of its emission allows for the arrival of individual pulses to be timed. By measuring the arrival time of pulses, astronomers observed the delay of pulse arrivals from PSR J1614–2230 when it was passing behind its companion from the vantage point of Earth. By measuring this delay, known as the Shapiro delay, astronomers determined the mass of PSR J1614–2230 and its companion. The team performing the observations found that the mass of PSR J1614–2230 is 1.97 ± 0.04 M☉. This mass made PSR J1614–2230 the most massive known neutron star at the time of discovery, and rules out many neutron star equations of state that include exotic matter such as hyperons and kaon condensates. In 2013, a slightly higher neutron star mass measurement was announced for PSR J0348+0432, 2.01 ± 0.04 M☉. This confirmed the existence of such massive neutron stars using a different measuring technique.
  • 926
  • 04 Nov 2022
Topic Review
Soyuz 5
Soyuz 5 (Russian: Союз 5, Union 5) was a Soyuz mission using the Soyuz 7K-OK spacecraft launched by the Soviet Union on 15 January 1969, which docked with Soyuz 4 in orbit. It was the first docking of two crewed spacecraft of any nation, and the first transfer of crew from one space vehicle to another of any nation, the only time a transfer was accomplished with a space walk – two months before the United States Apollo 9 mission performed the first internal crew transfer. The mission, flown by cosmonauts Boris Volynov, Aleksei Yeliseyev, and Yevgeny Khrunov, was also memorable for its dramatic re-entry. The craft's service module did not separate, so it entered the atmosphere nose-first, leaving Volynov hanging by his restraining straps. As the craft aerobraked, the atmosphere burned through the service module, allowing the remaining descent module to right itself before the escape hatch was burned through. During the descent, the parachute lines tangled and the landing rockets failed, resulting in a hard landing that broke Volynov's teeth.
  • 925
  • 03 Nov 2022
Topic Review
The Structure and Evolution of Stars
Generally speaking, stars consist of three regimes: a core, an envelope, and an atmosphere from which the light emerges. Depending on the stellar mass and the evolutionary stage, cores and envelopes can be either radiative or convective. These regions define the (dominant) form of energy transport, but their physical definition and the interface between them represent a large source of uncertainty in stellar structure theory. Whilst stellar atmospheres are key messengers of astronomical information, they are also physical laboratories of radiation pressure leading to radiation-driven winds for high-mass stars and chemical mixing and transport phenomena such as radiative levitation in hot low-mass stars, which is where heavy elements with large cross-sections can gain momentum by absorbing photons from outflowing radiation.
  • 925
  • 25 Oct 2023
Topic Review
Stars
Stars are massive and luminous spheres of hot plasma. A plasma is a gas that's so hot that the nuclei and the electrons of the atoms have separated, so it's essentially a hot "soup" that contains positive ions (atom nuclei) and electrons. Stars typically consist of 70-75% hydrogen, about 25% helium and some heavier trace elements. The composition can vary significantly, mainly depending on the age of the star and whether it was born in the early times of our universe or more recently. The Sun, for example, is composed of 74.9% hydrogen and 23.8% helium, leaving less than 2% for all other elements heavier than helium. During most of their lifespan stars generate radiant energy by fusing hydrogen into helium, a process that converts mass into energy and releases energy in the form of radiation of various wavelengths. In order to maintain nuclear fusion in their cores, stars have core temperatures ranging from 4 million to 40 million degrees Kelvin. 
  • 924
  • 25 Mar 2025
Biography
Yury Romanenko
Yury Viktorovich Romanenko (Russian: Ю́рий Ви́кторович Романе́нко, Jurij Viktorovič Romanenko; born August 1, 1944) is a former Soviet cosmonaut, twice Hero of the Soviet Union (March 16, 1978 and September 26, 1980). Over his career, Yury Romanenko spent a total of 430 days 20 hours 21 minutes 30 seconds in space and 18 hours in space walks.[1] In 1987 he was a reside
  • 914
  • 07 Dec 2022
Topic Review
Radio-Mode Feedback in Galaxies
The Active Galactic Nuclei (AGN) population can be represented by two main categories. In the first category, Quasars and Seyfert galaxies, sources of high bolometric luminosities, capable of generating winds through radiation pressure due to its accretion rate close to Eddington, usually found in wide angle outflows, are commonly distinguished as radiative-mode (or sometimes also called as quasar-mode) AGN. In the second category, the so called radio-mode AGN (or jet-mode, or kinetic-mode), the central engine launches powerful collimated jets of relativistic particles accelerated in the inner regions of the accretion disk due to its intense magnetic fields. The origin of the difference between these two categories is believed to happen within the accretion disk structure and internal thermodynamics, and the resulting mass accretion rates.
  • 899
  • 28 Jun 2023
Topic Review
Transit of Venus, 2012
The 2012 transit of Venus, when the planet Venus appeared as a small, dark spot passing across the face of the Sun, began at 22:09 UTC on 5 June 2012, and finished at 04:49 UTC on 6 June. Depending on the position of the observer, the exact times varied by up to ±7 minutes. Transits of Venus are among the rarest of predictable celestial phenomena and occur in pairs. Consecutive transits per pair are spaced 8 years apart, and consecutive pairs occur more than a century apart: The previous transit of Venus took place on 8 June 2004 (preceded by transits on 9 December 1874 and 6 December 1882); the next pair of transits will occur on 10–11 December 2117 and in December 2125.
  • 895
  • 28 Nov 2022
Topic Review
Water Ice Resources on Shallow Subsurface of Mars
The planet Mars is the most probable among the terrestrial planets in our solar system to support human settlement or colonization in the future. The detection of water ice or liquid water on the shallow subsurface of Mars is a crucial scientific objective for both the Chinese Tianwen-1 and United States Mars 2020 missions, which were launched in 2020. Both missions were equipped with Rover-mounted ground-penetrating radar (GPR) instruments, specifically the RoPeR on the Zhurong rover and the RIMFAX radar on the Perseverance rover. The in situ radar provides unprecedented opportunities to study the distribution of shallow subsurface water ice on Mars with its unique penetrating capability. The presence of water ice on the shallow surface layers of Mars is one of the most significant indicators of habitability on the extraterrestrial planet.
  • 891
  • 27 Mar 2024
Topic Review
Kepler-86
Kepler-86, PH2 or KIC 12735740 (2MASS 19190326+5157453), is a G-type star 1,130 ly (350 pc) distant within the constellation Cygnus. Roughly the size and temperature of the Sun, PH2 gained prominence when it was known to be the host of one of 42 planet candidates detected by the Planet Hunters citizen science project in its second data release. The candidate orbiting around PH2, known as PH2 b, had been determined to have a spurious detection probability of only 0.08%, thus effectively confirming its existence as a planet. Located in its parent star's habitable zone, PH2 b (or Kepler-86b) is a "Jupiter-size" gas giant which may have a natural satellite suitable for hosting life. The report of the confirmed detection of PH2 b was submitted on January 3, 2013. It was discovered by amateur Pole Rafał Herszkowicz using his laptop and access to the Internet project with data from the Kepler space observatory.
  • 887
  • 24 Oct 2022
Topic Review
Testing General Relativity with Gravitational Waves
The detections of gravitational-wave (GW) signals from compact binary coalescence by ground-based detectors have opened up the era of GW astronomy. These observations provide opportunities to test Einstein’s general theory of relativity at the strong-field regime. 
  • 884
  • 18 Jan 2022
Topic Review
Large UV Optical Infrared Surveyor
The Large UV Optical Infrared Surveyor (LUVOIR) is a multi-wavelength space observatory concept being developed by the Goddard Space Flight Center and proposed for the Decadal Survey Concept Study started in January 2016. The concept is based on a mirror from 8 m to 18 m in diameter, and covering the ultraviolet, visible and infrared wavelengths. It would be a Large Strategic Science Mission and be up for selection sometime after 2020. LUVOIR is a set of goals and requirements for a space telescope, but is not a specific design. More concrete proposals have their own names, such as ATLAST and HDST. One of those will be selected to become LUVOIR.
  • 883
  • 23 Nov 2022
Biography
Jules Aarons
Jules Aarons (October 3, 1921 – November 21, 2008) was an American space physicist known for his study of radio-wave propagation, and a photographer known for his street photography in Boston. Aarons was born in the Bronx, NY, where his father worked in the garment industry. He graduated from the City College of New York in 1942. During World War II he served in the Army Signal Corps. He st
  • 871
  • 14 Nov 2022
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