Pictor is a small constellation in the Southern Celestial Hemisphere, located between the star Canopus and the Large Magellanic Cloud. Its name is Latin for painter, and is an abbreviation of the older name Equuleus Pictoris (the ‘painter’s easel’). Pictor is 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. In the equatorial coordinate system, the right ascension coordinates of the constellation lie between 04h 32.5m and 06h 52.0m, while the declination coordinates are between −42.79° and −64.15°. Pictor culminates each year at 9 p.m. on 17 March. Its position in the far Southern Celestial Hemisphere means that the whole constellation is visible to observers south of latitude 26°N, and parts become circumpolar south of latitude 35°S.
Pictor, shown with the name Pluteum Pictoris on Chart XX of the Uranographia star atlas of Johann Bode (1801). Bode closely followed Lacaille’s original depiction of this constellation, unlike in many other cases. The bright star at centre right is Canopus on the steering oar of the ship Argo. [http://www.ianridpath.com/startales/pictor.htm]
The French astronomer Abbé Nicolas-Louis de Lacaille first described Pictor as le Chevalet et la Palette (the easel and palette) in 1756, after observing and cataloguing 10,000 southern stars during a two-year stay at the Cape of Good Hope. He devised 14 new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe. All but one honored instruments that symbolised the Age of Enlightenment. He gave these constellations Bayer designations, including ten stars in Pictor now named Alpha to Nu Pictoris. He labelled the constellation Equuleus Pictorius on his 1763 chart, the word ‘Equuleus’ meaning small horse, or easel- perhaps from an old custom among artists of carrying a canvas on a donkey. The German astronomer 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.
[http://astropixels.com/constellations/charts/Pic.html]
[http://www.dibonsmith.com/pic_con.htm]
Pictor is a faint constellation; its three brightest stars can be seen near the prominent Canopus. Within the constellation’s borders, there are 49 stars brighter than or equal to apparent magnitude 6.5. Located about 97 light-years away from Earth, Alpha Pictoris is the brightest star in the constellation; it is a white main-sequence star with an apparent magnitude of 3.3, and spectral type A8VnkA6. A rapidly spinning star with a projected rotational velocity estimated at 206 km/s, it has a shell of circumstellar gas.
ESO image of a planet near Beta Pictoris
[https://en.wikipedia.org/wiki/Beta_Pictoris]
Beta Pictoris is another white main sequence star of spectral type A6V and apparent magnitude 3.86. Located around 63.4 light-years distant from Earth, it is a member of the Beta Pictoris moving group- a group of 17 star systems around 12 million years old moving through space together. In 1984 Beta Pictoris was the first star discovered to have a debris disk. Since then, an exoplanet about eight times the mass of Jupiter has been discovered orbiting approximately 8 astronomical units (AU) away from the star- a similar distance as that between our Sun and Saturn. The European Southern Observatory (ESO) confirmed its presence through the use of direct imagery with the Very Large Telescope in late 2009.
Gamma Pictoris is an orange giant of spectral type K1III that has swollen to 1.4 times the diameter of the Sun. Shining with an apparent magnitude of 4.5, it lies 174 light-years distant from Earth.
Location of HD 40307 in the night sky. The star is marked within the red diamond below the word ‘Pictor.’
[https://en.wikipedia.org/wiki/HD_40307]
Aside from Beta, five other stars in Pictor are known to host planetary systems. HD 40307 is an orange main sequence star of spectral type K2.5V and apparent magnitude 7.17 located about 42 light-years away. Doppler spectroscopy with the High Accuracy Radial Velocity Planet Searcher (HARPS) indicates that HD 40307 is host to six super-Earth planets, one of which, HD 40307 g, lies in the circumstellar habitable zone of the star, and is not close enough to be tidally locked (i.e. with the same face always facing the star), unlike the other planets in the same system, and many other planets which orbit close to their parent stars.
Kapteyn’s Star: Comparison with Sun, Jupiter and Earth.
[https://en.wikipedia.org/wiki/Kapteyn%27s_Star]
Kapteyn’s Star, a nearby red dwarf at the distance of 12.78 light-years, has a magnitude of 8.8. It has the largest proper motion of any star in the sky after Barnard’s Star. Moving around the Milky Way in the opposite direction to most other stars, it may have originated in a dwarf galaxy that was merged into the Milky Way, with the main remnant being the Omega Centauri globular cluster. In 2014 analysis of the doppler variations of Kapteyn’s Star with the HARPS spectrograph showed that it hosts two super-Earths- Kapteyn b and Kapteyn c. Kapteyn b is the oldest-known potentially habitable planet, estimated to be possibly 11 billion years old.
Pictor includes NGC 1705, an irregular dwarf galaxy:
The Stars of NGC 1705
Some 2,000 light-years across, NGC 1705 is small as galaxies go, similar to our Milky Way’s own satellite galaxies, the Magellanic Clouds. At a much larger distance of 17 million light-years, the stars of NGC 1705 are still easily resolved in this beautiful image constructed from data taken in 1999 and 2000 with the Hubble Space Telescope. Most of the younger, hot, blue stars in the galaxy are seen to be concentrated in a large central star cluster with the older, cooler, red stars more evenly distributed. Possibly 13 billion years old, NGC 1705 could well have been forming stars through out its lifetime while light from its most recent burst of star formation reached Earth only 30 million years ago. This gradually evolving dwarf irregular galaxy lacks organized structures like spiral arms and is thought to be a nearby analog to the first galaxies to form in the early Universe.
[http://apod.nasa.gov/apod/ap030423.html]
Pictor A, around 485 million light-years away, is a double-lobed radio galaxy and a powerful source of radio waves in the Southern Celestial Hemisphere. From a supermassive black hole at its center, a relativistic jet shoots out to an X-ray hot spot 800,000 light years away:
Pictor A: Blast from Black Hole in a Galaxy Far, Far Away
The Star Wars franchise has featured the fictitious ‘Death Star,’ which can shoot powerful beams of radiation across space. The Universe, however, produces phenomena that often surpass what science fiction can conjure.
The Pictor A galaxy is one such impressive object. This galaxy, located nearly 500 million light years from Earth, contains a supermassive black hole at its center. A huge amount of gravitational energy is released as material swirls towards the event horizon, the point of no return for infalling material. This energy produces an enormous beam, or jet, of particles traveling at nearly the speed of light into intergalactic space.
To obtain images of this jet, scientists used NASA’s Chandra X-ray Observatory at various times over 15 years. Chandra’s X-ray data (blue) have been combined with radio data from the Australia Telescope Compact Array (red) in this new composite image.
By studying the details of the structure seen in both X-rays and radio waves, scientists seek to gain a deeper understanding of these huge collimated blasts.
The jet [to the right] in Pictor A is the one that is closest to us. It displays continuous X-ray emission over a distance of 300,000 light years. By comparison, the entire Milky Way is about 100,000 light years in diameter. Because of its relative proximity and Chandra’s ability to make detailed X-ray images, scientists can look at detailed features in the jet and test ideas of how the X-ray emission is produced.
In addition to the prominent jet seen pointing to the right in the image, researchers report evidence for another jet pointing in the opposite direction, known as a ‘counterjet.’ While tentative evidence for this counterjet had been previously reported, these new Chandra data confirm its existence. The relative faintness of the counterjet compared to the jet is likely due to the motion of the counterjet away from the line of sight to the Earth.
The labeled image shows the location of the supermassive black hole, the jet and the counterjet. Also labeled is a ‘radio lobe’ where the jet is pushing into surrounding gas and a ‘hotspot’ caused by shock waves- akin to sonic booms from a supersonic aircraft- near the tip of the jet.
The detailed properties of the jet and counterjet observed with Chandra show that their X-ray emission likely comes from electrons spiraling around magnetic field lines, a process called synchrotron emission. In this case, the electrons must be continuously re-accelerated as they move out along the jet. How this occurs is not well understood
The researchers ruled out a different mechanism for producing the jet’s X-ray emission. In that scenario, electrons flying away from the black hole in the jet at near the speed of light move through the sea of cosmic background radiation (CMB) left over from the hot early phase of the Universe after the Big Bang. When a fast-moving electron collides with one of these CMB photons, it can boost the photon’s energy up into the X-ray band.
The X-ray brightness of the jet depends on the power in the beam of electrons and the intensity of the background radiation. The relative brightness of the X-rays coming from the jet and counterjet in Pictor A do not match what is expected in this process involving the CMB, and effectively eliminate it as the source of the X-ray production in the jet.
[http://chandra.harvard.edu/photo/2016/pictora/]
[https://upload.wikimedia.org/wikipedia/commons/e/e3/SPT-CL_J0546-5345.jpg]
SPT-CL J0546-5345 is one of the most massive galaxy clusters ever found in the early universe. It is thought to be 7 billion light years away. It was discovered at the South Pole Telescope in 2008 by the Sunyaev-Zel’dovich-Effect. The cluster has a redshift of z=1.067. Follow-up studies using the Spitzer, Chandra and optical telescopes allowed to identify cluster members and to measure the redshift. Using the velocity dispersion, the cluster mass has been estimated to 1015 solar masses.
[https://en.wikipedia.org/wiki/SPT-CL_J0546-5345]
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. It was also notable for its extraordinarily long X-ray afterglow, detectable 642 days (nearly two years) after the original event. The event was remote, with a redshift of 0.54.
[https://en.wikipedia.org/wiki/Pictor]
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