Pavo is a constellation in the southern sky with the Latin name for peacock. It is bordered by Telescopium to the north, Apus and Ara to the west, Octans to the south, and Indus to the east and northeast. Covering 378 square degrees, it ranks 44th of the 88 modern constellations in size and covers 0.916% of the night sky. In the equatorial coordinate system, the right ascension coordinates of the constellation lie between 18h 10.4m and 21h 32.4m, while the declination coordinates are between −56.59° and −74.98°. As one of the deep southern constellations, it remains below the horizon at latitudes north of the 30th parallel in the Northern Hemisphere, and is circumpolar at latitudes south of the 50th parallel in the Southern Hemisphere. Some of the stars in the constellation form an asterism known as ‘the Saucepan’ in Australia when they are used for navigation, as they point toward the southern celestial pole. The constellations Pavo, Grus, Phoenix and Tucana are collectively known as the ‘Southern Birds.’
Pavo flourishes a truncated tail on Chart XX of the Uranographia of Johann Bode (1801)
[http://www.ianridpath.com/startales/pavo.htm]
Pavo was one of the twelve constellations established by Dutch astronomer Petrus Plancius from the observations of the southern sky by Dutch explorers Pieter Dirkszoon Keyser and Frederick de Houtman, who had sailed on the first Dutch trading expedition, known as the Eerste Schipvaart, to the East Indies. It first appeared on a 35-cm (14 in) diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in German cartographer Johann Bayer’s Uranometria of 1603. De Houtman included it in his southern star catalogue the same year under the Dutch name De Pauww, ‘The Peacock.’ An alternate Latin name for the constellation was Junonia Avis.
According to Mark Chartrand, Plancius may not have been the first to designate this group of stars as a peacock, as in Greek myth the stars that are now the Peacock were Argos (or Argus), builder of the ship Argo. He was changed by the goddess Juno into a peacock and placed in the sky along with his ship. Indeed, the peacock symbolized the starry firmament for the Greeks, and the goddess Hera was believed to drive through the heavens in a chariot drawn by peacocks.
The peacock and the ‘Argus’ nomenclature are also prominent in a different myth, in which Io, a beautiful princess of Argos, was lusted after by Zeus (Jupiter). Zeus changed Io into a heifer to deceive his wife (and sister) Hera and couple with her. Hera saw through Zeus’s scheme and asked for the heifer as a gift. Zeus, unable to refuse such a reasonable request, reluctantly gave the heifer to Hera, who promptly banished Io and arranged for Argus Panoptes, a creature with one hundred eyes, to guard the now-pregnant Io from Zeus. Meanwhile, Zeus entreated Hermes to save Io; Hermes used music to lull Argus Panoptes to sleep, then slew him. Hera adorned the tail of a peacock- her favorite bird- with Argus’s eyes in his honor.
As recounted in Ovid’s Metamorphoses, the death of Argus Panoptes also contains an explicit celestial reference: “Argus lay dead; so many eyes, so bright quenched, and all hundred shrouded in one night. Saturnia [Hera] retrieved those eyes to set in place among the feathers of her bird [the peacock, Pavo] and filled his tail with starry jewels.”
It is uncertain whether the Dutch astronomers had the Greek mythos in mind when creating Pavo but, in keeping with other constellations introduced by Plancius through Keyser and De Houtmann, the ‘peacock’ in the new constellation likely referred to the green peacock, which the explorers would have encountered in the East Indies, rather than the blue peacock known to the ancient Greeks.
The Wardaman people of the Northern Territory in Australia saw the stars of Pavo and the neighbouring constellation Ara as flying foxes.
[http://www.davidmalin.com/fujii/source/Pav.html]
[https://www.thoughtco.com/constellations-pictures-gallery-4122769]
Lying near the constellation’s northern border with Telescopium is Alpha Pavonis, the brightest star in Pavo. Its proper name- Peacock- is an English translation of the constellation’s name. Alpha has an apparent (or visual) magnitude of 1.91 and spectral type B2IV. It is a spectroscopic binary system, one estimate placing the distance between the pair of stars as 0.21 astronomical units (AU), or half the distance between Mercury and the Sun. The two stars rotate around each other in a mere 11 days and 18 hours. The star system is located around 180 light years away from Earth.
With an apparent magnitude of 3.43, Beta Pavonis is the second-brightest star in the constellation. A white giant of spectral class A7III, it is an aging star that has used up the hydrogen fuel at its core and has expanded and cooled after moving off the main sequence. It lies 135 light years away from the Solar System.
Lying a few degrees west of Beta is Delta Pavonis, a nearby Sun-like but more evolved star; this is a yellow subgiant of spectral type G8IV and apparent magnitude 3.56 that is only 19.9 light years distant from Earth.
East of Beta and at the constellation’s eastern border with Indus is Gamma Pavonis, a fainter, solar-type star 30 light years from Earth with a magnitude of 4.22 and stellar class F9V.
Located in the west of the constellation and depicting the peacock’s tail is Eta Pavonis. At apparent magnitude 3.6, Eta is a luminous orange giant of spectral type K2II some 350 light years distant from Earth.
In the south of the constellation, Epsilon Pavonis is a 3.95-magnitude white main sequence star of spectral type A0Va located around 105 light years distant from Earth. It appears to be surrounded by a narrow ring of dust at a distance of 107 AU.
West of Epsilon Pavonis is located Zeta Pavonis, a class K0III (orange giant) star. Its apparent magnitude is 4.01 and it is approximately 218 light years away based on parallax. Zeta Pavonis has a companion, probably optical, of apparent magnitude 12.0 at about 55.6" separation.
[https://en.wikipedia.org/wiki/Zeta_Pavonis]
Three-color image of SCR1845-6357AB generated from the SDI filter images (blue=1.575 micrometer, green=1.600 micrometer, red=1.625 micrometer). Because the T-dwarf fades away towards the longer wavelengths, it appears quite blue in this image. It is roughly 50 times fainter than the star and is separated from it by an angle of 1.17 arcsecond on the sky (4.5 times the Earth-Sun distance).
SCR 1845-6357 is a binary system, about 12.6 light-years away in the constellation Pavo. The primary, SCR 1845-6357A, is a faint (apparent magnitude 17.4) red dwarf with a mass of about 7% of the Sun’s.
The secondary is a brown dwarf, designated SCR 1845-6357B. The companion, classified as a T-dwarf, has an observed projected distance of 4.1 AU, an estimated mass between 40 and 50 times the mass of Jupiter, and an estimated effective temperature of 950 K.
[https://en.wikipedia.org/wiki/SCR_1845-6357]
An artist’s conception of a body about the size of the Moon slamming into a body the size of Mercury. As the bodies hit each other at speeds exceeding 10 km per second (about 22,400 mph), a huge flash of light is emitted, and their rocky surfaces are vaporized and melted, spraying hot matter everywhere.
HD 172555 is a white-hot A5V star located relatively close by, 95 light years from Earth in the direction of the constellation Pavo. Spectrographic evidence indicates a relatively recent collision between two planet-sized bodies that destroyed the smaller of the two, which had been at least the size of Earth’s moon, and severely damaged the larger one, which was at least the size of Mercury. Evidence of the collision was detected by NASA’s Spitzer Space Telescope.
HD172555 was first recognized in the 1980s as being unusually bright in the mid-infrared by the IRAS sky survey. Follow-up ground based observations confirmed the unusually strong nature of the infrared spectral emission from this system, much brighter than what would be emitted normally from the star’s surface.
Comparison with current planetary formation theories suggests that the HD172555 is in the early stages of terrestrial (rocky) planet formation. But what makes HD 172555 special is the presence of a large amount of unusual silicaceous material- amorphous silica and SiO gas- not the usual rocky materials, silicates like olivine and pyroxene, which make up much of the Earth as well.
The material had to have been created in a hypervelocity impact between two large bodies; relative velocities at impacts less than 10 km/s would not transform the ubiquitous olivine and pyroxene into silica and SiO gas. Giant impacts at this speed typically destroy the incident body, and melt the entire surface of the impactee.
Massive hypervelocity impacts happen in young planetary systems. Rocky protoplanets, and possibly planets, exist in the HD172555 system, at about 12 Myr after its formation. If the collision happened within the last few thousand years, there is likely a protoplanet in the HD172555 system with a liquid magma surface. This is not unexpected; a simple calculation of the gravitational binding energy of the Earth, shows that the energy released in assembling the Earth is about 10x the amount needed to melt it.
[https://en.wikipedia.org/wiki/HD_172555]
Artist’s impression of HD 181433 b
[https://commons.wikimedia.org/wiki/File:Artist%27s_impression_of_HD_181433_b.jpg]
HD 181433 is a star located approximately 87 light-years away in the constellation of Pavo). Its entry in the Hipparcos catalogue lists a spectral type of K5V, classifying it as a dwarf star.
Orbiting the star are three planets, whose discovery was announced in 2008. The inner planet (HD 181433b) has a mass at least 7.5 times that of Earth, and is termed a super-Earth. The middle planet (HD 181433c) and the outer planet (HD 181433d) are gas giants. The orbital periods for three planets are 9.3743 days for a 7.56 ME planet, 962 days for a 0.64 MJ planet, and 2172 days for a 0.54 MJ planet.
[https://en.wikipedia.org/wiki/HD_181433]
The deep-sky objects in Pavo include NGC 6752- the third-brightest globular cluster in the sky, after 47 Tucanae and Omega Centauri. An estimated 100 light years across, it is thought to contain 100,000 stars:
At the core of NGC 6752
This sharp Hubble Space Telescope view looks deep into NGC 6752. Some 13,000 light-years away toward the southern constellation Pavo, the globular star cluster roams the halo of our Milky Way galaxy. Over 10 billion years old, NGC 6752 holds over 100 thousand stars in a sphere about 100 light-years in diameter, but the Hubble image frame spans the central 10 or so light-years and resolves stars near the dense cluster core. In fact the frame includes some of the cluster's blue straggler stars, stars which appear to be too young and massive to exist in a cluster whose stars are all expected to be at least twice as old as the Sun. Explorations of the NGC 6752 have also indicated that a remarkable fraction of the stars near the cluster's core, are multiple star systems, supporting arguments that star mergers and collisions in the dense stellar environment can create the cluster’s blue straggler stars.
[http://apod.nasa.gov/apod/ap120210.html]
Lying three degrees to the south of NGC 6752 is NGC 6744, a spiral galaxy around 30 million light years away from Earth that resembles the Milky Way, but is twice its diameter:
Spiral Galaxy NGC 6744
Big, beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo. We see the disk of the nearby island universe tilted towards our line of sight. Orientation and composition give a strong sense of depth to this colorful galaxy portrait that covers an area about the angular size of the full moon. This giant galaxy’s yellowish core is dominated by the light from old, cool stars. Beyond the core, spiral arms filled with young blue star clusters and pinkish star forming regions sweep past a smaller satellite galaxy at the lower left, reminiscent of the Milky Way’s satellite galaxy the Large Magellanic Cloud.
[http://apod.nasa.gov/apod/ap140808.html]
NGC 6872, also known as the Condor Galaxy, is a large barred spiral galaxy in the constellation Pavo. It is 212 million light-years (65 Mpc) from Earth and is approximately five billion years old. NGC 6872 is interacting with the lenticular galaxy IC 4970, which is less than one twelfth as large. The galaxy has two elongated arms; from tip to tip, NGC 6872 measures 522,000 light-years (160,000 pc), making it one of the largest-known spiral galaxies. It was discovered on 27 June 1835 by English astronomer John Herschel:
An interacting colossus
This picture, taken by the NASA/ESA Hubble Space Telescope’s Wide Field Planetary Camera 2 (WFPC2), shows a galaxy known as NGC 6872 in the constellation of Pavo (The Peacock). Its unusual shape is caused by its interactions with the smaller galaxy that can be seen just above NGC 6872, called IC 4970. They both lie roughly 300 million light-years away from Earth.
From tip to tip, NGC 6872 measures over 500 000 light-years across, making it the second largest spiral galaxy discovered to date. In terms of size it is beaten only by NGC 262, a galaxy that measures a mind-boggling 1.3 million light-years in diameter! To put that into perspective, our own galaxy, the Milky Way, measures between 100 000 and 120 000 light-years across, making NGC 6872 about five times its size.
The upper left spiral arm of NGC 6872 is visibly distorted and is populated by star-forming regions, which appear blue on this image. This may have been be caused by IC 4970 recently passing through this arm- although here, recent means 130 million years ago! Astronomers have noted that NGC 6872 seems to be relatively sparse in terms of free hydrogen, which is the basis material for new stars, meaning that if it weren’t for its interactions with IC 4970, NGC 6872 might not have been able to produce new bursts of star formation.
[https://www.spacetelescope.org/images/potw1437a/]
Pavo is the radiant of two annual meteor showers: the Delta Pavonids and August Pavonids. Appearing from 21 March to 8 April and generally peaking around 5 and 6 April, Delta Pavonids are thought to be associated with Comet Grigg-Mellish. This shower was discovered by one Michael Buhagiar from Perth, Australia, who observed meteors on six occasions in eleven years between 1969 and 1980. The August Pavonids peak around August 31 and are thought to be associated with the Halley-type Comet Levy (P/1991 L3).
[https://en.wikipedia.org/wiki/Pavo_%28constellation%29]
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