Pictor

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Pictor
Constellation
59th)
Main stars3
Bayer/Flamsteed
stars
15
Stars with planets6
Stars brighter than 3.00m0
Stars within 10.00 pc (32.62 ly)1
Brightest starα Pic (3.30m)
Messier objects0
Meteor showers0
Bordering
constellations
Caelum
Carina
Columba
Dorado
Puppis
Volans
Visible at latitudes between +26° and −90°.
Best visible at 21:00 (9 p.m.) during the month of January.

Pictor is a

cataclysmic variable star system that flared up as a nova, reaching apparent (visual) magnitude 1.2 in 1925 before fading into obscurity.[a]

Pictor has attracted attention because of its second-brightest star

jet of plasma from a supermassive black hole at its centre. In 2006, a gamma-ray burstGRB 060729—was observed in Pictor, its extremely long X-ray afterglow
detectable for nearly two years.

History

Early depiction c.1756, when known as le Chevalet et la Palette; Canopus of Carina (the keel, or the hull, of the ship) seen at upper right

The French astronomer Abbé

Johann Bode called it Pluteum Pictoris. The name was shortened to its current form in 1845 by the English astronomer Francis Baily on the suggestion of his countryman Sir John Herschel.[5]

Characteristics

Pictor is a small constellation bordered by Columba to the north, Puppis and Carina to the east, Caelum to the northwest, Dorado to the southwest and Volans to the south. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Pic".[10] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 18 segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 04h 32.5m and 06h 52.0m , while the declination coordinates are between −42.79° and −64.15°.[11] Pictor culminates each year at 9 p.m. on 17 March.[12] Its position in the far Southern Celestial Hemisphere means that the whole constellation is visible to observers south of latitude 26°N,[13][d] and parts become circumpolar south of latitude 35°S.[14]

Features

Stars

A photograph showing constellation Pictor as it can be seen by the naked eye (lines have been added that join up its three main stars). The bright star seen near Pictor is Canopus.

Pictor is a faint constellation; its three brightest stars can be seen near the prominent

direct imagery with the Very Large Telescope in late 2009.[24]

orange giant of spectral type K1III that has swollen to 1.4 times the diameter of the Sun.[25] Shining with an apparent magnitude of 4.5, it lies 174 light-years distant from Earth.[26] HD 42540, called 47 Pictoris by American astronomer Benjamin Apthorp Gould, is a slightly cooler orange giant, with a spectral type of K2.5III and average magnitude 5.04.[27] It has also been suspected of being a variable star.[28] Lacaille mistakenly named this star Mu Doradus, but had recorded its Right Ascension one hour too low.[29] Lacaille named two neighbouring stars Eta Pictoris.[8][g] Eta2 Pictoris, also known as HR 1663, is an orange giant of spectral type K5III and apparent magnitude 5.05. 474 light-years distant,[31] it has a diameter 5.6 times that of the Sun.[25] Eta1 Pictoris, also known as HR 1649, is 85 light-years distant and is a main sequence star of spectral type F5V and visual magnitude 5.38.[32] A double star, it has a companion of magnitude 13; the two are separated by 11 arcseconds.[33]

Beta Pictoris Comparison[34]

Located about 1298 light-years from Earth,

spectroscopic binary system composed of an A-type star and an F-type star which rotate around each other in a very close orbit. The latter star is elliptical in shape and itself varies in brightness.[38] The visual magnitude ranges between 7.37 and 7.53 every 20 hours.[39]

Aside from Beta, five other stars in Pictor are known to host planetary systems.

Kapteyn b and Kapteyn c, but the existence of these exoplanet was disproven in 2021.[4] It is believed that these planets were actually just artifacts of the Kapteyn' star's rotation and activity.[4]

Located 1.5 degrees west southwest of Alpha,

cataclysmic variable that flared up as a nova, reaching magnitude 1.2 on 9 June 1925.[43] Six months after its peak brightness, it had faded to be invisible to the unaided eye, and was magnitude 12.5 by 1975.[45] RR Pictoris is a close binary system composed of a white dwarf and secondary star that orbit each other every 3.48 hours—so close that the secondary is filling up its Roche lobe with stellar material, which is then transferred onto the first star's accretion disk. Once this material reaches a critical mass, it ignites and the system brightens tremendously. Calculations from the orbital speed suggest the secondary star is not dense enough for its size to still be on the main sequence, so it also must have begun expanding and cooling already after its core ran out of hydrogen fuel.[46] The RR Pictoris system is estimated to lie around 1300 light-years distant from Earth.[47]

Deep-sky objects

jet of plasma emanating from Pictor A

relativistic jet shoots out to an X-ray hot spot 800,000 light years away.[51] SPT-CL J0546-5345 is a massive galaxy cluster located around 7 billion light-years away with a mass equivalent to approximately 800 trillion suns.[52]

GRB 060729 was a gamma-ray burst that was first observed on 29 July 2006. It is likely the signal of a type Ic supernova—the core collapse of a massive star.[53] It was also notable for its extraordinarily long X-ray afterglow, detectable 642 days (nearly two years) after the original event.[54] The event was remote, with a redshift of 0.54.[53]

See also

  • Pictor (Chinese astronomy)

Notes

  1. ^ Deneb, the 19th-brightest star in the night sky, has a magnitude of 1.25.[1][2][3]
  2. ^ His observatory was in a private house on the shores of Table Bay in Cape Town.[6]
  3. ^ He erred in naming the wrong star with the Greek letter epsilon, which is now not used.[8]
  4. ^ While parts of the constellation technically rise above the horizon to observers between 26°N and 47°N, stars within a few degrees of the horizon are to all intents and purposes unobservable.[13]
  5. ^ Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies[16]
  6. absorption lines in the spectrum are broad and nebulous, because of the rapid spin of the star.[18]
  7. ^ Like Bayer, Lacaille would simply give two stars very close to each other the same designation with no modifier. It was left to later astronomers such as Gould to designate Eta1, Eta2 etc.[30]

References

Citations

Sources

Online sources

External links


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