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Topic Review
Mensa
Mensa is a faint constellation in the southern celestial hemisphere, first introduced by the French astronomer Nicolas Louis de Lacaille in the 18th century. It is named after the Table Mountain in South Africa.
  • 455
  • 15 Mar 2024
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.
  • 453
  • 28 Jun 2023
Topic Review
Antlia
Antlia is a constellation recognized by the International Astronomical Union (IAU), situated in the southern celestial hemisphere. Named after the air pump, it is a relatively faint constellation with no stars brighter than fourth magnitude, but it contains several interesting deep-sky objects, including the Antlia Galaxy Cluster, making it a fascinating subject for exploration by astronomers.
  • 450
  • 15 Mar 2024
Topic Review
Soyuz 4
Soyuz 4 (Russian: Союз 4, Union 4) was launched on 14 January 1969, carrying cosmonaut Vladimir Shatalov on his first flight. The aim of the mission was to dock with Soyuz 5, transfer two crew members from that spacecraft, and return to Earth. The previous Soyuz flight (Soyuz 3) was also a docking attempt but failed for various reasons. The radio call sign of the crew was Amur, while Soyuz 5 was Baikal. This referred to the trans-Siberian railway project called the Baikal-Amur Mainline, which was in development at the time.
  • 442
  • 03 Nov 2022
Topic Review
Lunar Regolith Penetrating Radar
An extraordinary component of this mission is the “Lunar Regolith Penetrating Radar” (LRPR) housed within its lander, which currently stands as the most advanced payload in terms of vertical resolution among all penetrating radars employed in lunar exploration.
  • 441
  • 10 Nov 2023
Topic Review
Black Holes and Quantum Mechanics
Mass and spin distributions of stellar mass black holes (BH) are important sources of information on the formation mechanism and the evolution of galaxies. The birth of a stellar-mass BH, ranging in the interval ~5–150 M⊙, is due to the spectacular phase of a massive star’s core collapse, an event involving the emission of multi-messenger signals such as neutrinos, GW’s and electromagnetic radiation in several bands.
  • 436
  • 03 Nov 2022
Topic Review
Historical Solar Eclipses and Implications in Celestial Mechanics
Solar and lunar eclipses are indeed the first astronomical phenomena which have been recorded since very early antiquity. Their periodicities gave birth to the first luni-solar calendars based on the Methonic cycle since the sixth century before Christ. 
  • 436
  • 23 Feb 2024
Topic Review
Caelum
Caelum, recognized by the International Astronomical Union (IAU), is a faint and small constellation in the southern celestial hemisphere. It was introduced by the French astronomer Nicolas Louis de Lacaille in the 18th century, representing a chisel, part of the sculptor's tools, in his constellation sketches.
  • 436
  • 29 Feb 2024
Topic Review
List of Unnumbered Minor Planets: 2003 U–Y
This is a partial list of unnumbered minor planets for principal designations assigned between 16 October 2003 and 31 December 2003 (U–Y).
  • 429
  • 24 Nov 2022
Topic Review
Pictor
Pictor, a relatively faint constellation in the southern celestial hemisphere, is named after the easel used by artists to hold their canvases. It is located between the star Canopus and the Large Magellanic Cloud.
  • 424
  • 15 Mar 2024
Topic Review
(6545) 1986 TR6
(6545) 1986 TR6, provisional designation 1986 TR6, is a Jupiter trojan from the Greek camp, approximately 53 kilometers (33 miles) in diameter. It was discovered on 5 October 1986, by Slovak astronomer Milan Antal at the Piwnice Astronomical Observatory in Poland. The dark D-type asteroid has a rotation period of 16.3 hours and belongs to the 90 largest Jupiter trojans. It has not been named since its numbering in September 1995.
  • 422
  • 09 Nov 2022
Topic Review
Aries
Aries, recognized by the International Astronomical Union (IAU), is a constellation in the northern celestial hemisphere. Representing the ram from ancient Greek mythology, Aries is one of the twelve zodiac constellations and holds significance in astrology and astronomy alike. Its celestial prominence and position along the ecliptic make it a notable feature in the night sky, marking the vernal equinox and heralding the beginning of spring in the northern hemisphere.
  • 417
  • 29 Feb 2024
Topic Review
TAUVEX
The Tel Aviv University Ultraviolet Explorer, or TAUVEX (Hebrew: טאווקס‎), is a space telescope array conceived by Noah Brosch of Tel Aviv University and designed and constructed in Israel for Tel Aviv University by El-Op, Electro-Optical Industries, Ltd. (a division of Elbit systems) acting as Prime Contractor, for the exploration of the ultraviolet (UV) sky. TAUVEX was selected in 1988 by the Israel Space Agency (ISA) as its first priority scientific payload. Although originally slated to fly on a national Israeli satellite of the Ofeq series, TAUVEX was shifted in 1991 to fly as part of a Spektr-RG international observatory, a collaboration of many countries with the Soviet Union (Space Research Institute) leading. Due to repeated delays of the Spektr project, caused by the economic situation in the post-Soviet Russia, ISA decided to shift TAUVEX to a different satellite. In early-2004 ISA signed an agreement with the Indian Space Research Organisation (ISRO) to launch TAUVEX on board the India n technology demonstrator satellite GSAT-4. The launch vehicle slated to be used was the GSLV with a new, cryogenic, upper stage. TAUVEX was a scientific collaboration between Tel Aviv University and the Indian Institute of Astrophysics in Bangalore. Its Principal Investigators were Noah Brosch at Tel Aviv University and Jayant Murthy at the Indian Institute of Astrophysics. Originally, TAUVEX was scheduled to be launched in 2008, but various delays caused the integration with GSAT-4 to take place only in November 2009 for a launch the following year. ISRO decided in January 2010 to remove TAUVEX from the satellite since the Indian-built cryogenic upper stage for GSLV was deemed under-powered to bring GSAT-4 to a geosynchronous orbit. GSAT-4 was subsequently lost in the 15 April 2010 launch failure of GSLV. On 13 March 2011 TAUVEX was returned to Israel and was stored at the Prime Contractor facility pending an ISA decision about its future. In 2012 ISA decided to terminate the TAUVEX project, against the recommendation of a committee it formed to consider its future that recommended its release for a high-altitude balloon flight.
  • 416
  • 10 Nov 2022
Topic Review
List of Unnumbered Minor Planets: 2002 T–Y
This is a partial list of unnumbered minor planets for principal designations assigned between 1 October 2002 and 31 December 2002 (T–Y).
  • 413
  • 10 Nov 2022
Topic Review
Valley Network
Valley networks are branching networks of valleys on Mars that superficially resemble terrestrial river drainage basins. They are found mainly incised into the terrain of the martian southern highlands, and are typically - though not always - of Noachian age (approximately four billion years old). The individual valleys are typically less than 5 kilometers wide, though they may extend for up to hundreds or even thousands of kilometers across the martian surface. The form, distribution, and implied evolution of the valley networks are of great importance for what they may tell us about the history of liquid water on the martian surface, and hence Mars' climate history. Some authors have argued that the properties of the networks demand that a hydrological cycle must have been active on ancient Mars, though this remains contentious. Objections chiefly arise from repeated results from models of martian paleoclimate suggesting high enough temperatures and pressures to sustain liquid water on the surface have not ever been possible on Mars. The advent of very high resolution images of the surface from the HiRISE, THEMIS and Context (CTX) satellite cameras as well as the Mars Orbital Laser Altimeter (MOLA) digital terrain models have drastically improved our understanding of the networks in the last decade.
  • 413
  • 25 Oct 2022
Topic Review
Canes Venatici
Canes Venatici, Latin for "hunting dogs," is a small northern constellation situated between Ursa Major and Boötes. It was introduced by Johannes Hevelius in the 17th century, representing the hunting dogs of Boötes, the Herdsman. The constellation is notable for hosting several interesting celestial objects, including the famous Whirlpool Galaxy (M51) and the Sunflower Galaxy (M63).
  • 403
  • 29 Feb 2024
Topic Review
List of Unnumbered Minor Planets: 2002 P–Q
This is a partial list of unnumbered minor planets for principal designations assigned between 1 August 2002 and 31 August 2002 (P–Q).
  • 402
  • 10 Nov 2022
Topic Review
Crater
Crater, Latin for "cup" or "bowl," is a small and inconspicuous constellation located in the southern celestial hemisphere. Positioned near the prominent constellation Hydra, Crater represents a celestial cup often associated with the mythological story of the Greek god Apollo and his daily ritual of sun-chariot driving.
  • 400
  • 08 Mar 2024
Topic Review
List of Exoplanetary Host Stars
The following is a list of exoplanetary host stars. The table contains information about the coordinates, spectral and physical properties, and number of confirmed planets. The two most important stellar properties are mass and metallicity because they determine how these planetary systems form. Stars of higher mass and metallicity tend to have more numerous and more massive planets. Most of the stars below are solar-type, mainly in the spectral classes F, G, and K, because astronomers tend to look for planets around stars similar to the Sun. Others are giants, which have used up all the hydrogen in their cores. Finding planets around giant stars gives clues as to how planetary systems evolve and how the properties of planets change with the evolution of the stars. As of April 2018, there are 2,816 stars with at least one confirmed planet, of which 628 stars have two or more confirmed planets; that is, 22% of all confirmed exoplanetary host stars have two or more confirmed planets. As of 2018, the star with the most confirmed planets is Kepler-90, with eight planets, although HD 10180 may have nine (two are unconfirmed). The most massive exoplanetary host star is Omicron Ursae Majoris (3.09 M☉), while the least massive is 2M J044144 (0.021 M☉). The most metal-rich star is NN Serpentis (1.744, 55.5 × Sun), while the most metal-poor is BD+20°2457 (−0.999, 0.100 × Sun). The nearest exoplanetary host star is Proxima Centauri (4.25 ly), while the most distant is NY Virginis (26940 ly). Visually, the brightest exoplanetary host star seen from Earth is Pollux (1.15), while the faintest is OGLE-2005-BLG-390L (27.98).
  • 399
  • 04 Oct 2022
Topic Review
Columba
Columba, Latin for "dove," is a constellation in the southern celestial hemisphere. First introduced by Dutch astronomer Petrus Plancius in the late 16th century, it represents the dove released by Noah from the ark in the biblical story of the Great Flood. Despite its small size, Columba contains several notable celestial objects, including the famous globular cluster NGC 1851 and various open star clusters, making it an intriguing target for astronomers and stargazers alike.
  • 398
  • 08 Mar 2024
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