[http://www.davidmalin.com/fujii/source/Tuc.html]
Tucana is a constellation of stars in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the late sixteenth century by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Irregular in shape, Tucana is bordered by Hydrus to the east, Grus and Phoenix to the north, Indus to the west and Octans to the south. Covering 295 square degrees, Tucana ranks 48th of the 88 constellations in size. In the equatorial coordinate system, the right ascension coordinates of the constellation lie between 22h 08.45m and 01h 24.82m, while the declination coordinates are between -56.31° and -75.35°. 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.
Tucana, holding in its beak a branch with a berry, as seen on Chart XX of the Uranographia star atlas of Johann Bode (1801). Behind its tail lies Nubecula Minor, the Small Magellanic Cloud (just visible at the lower right edge of the image), which is now part of the constellation.
[http://www.ianridpath.com/startales/tucana.htm]
Tucana is one of the twelve constellations established by the Dutch astronomer Petrus Plancius from the observations of the southern sky by the 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-centimetre-diameter (14 in) celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in the German cartographer Johann Bayer's Uranometria of 1603. Both Plancius and Bayer depict it as a toucan. De Houtman included it in his southern star catalogue the same year under the Dutch name Den Indiaenschen Exster, op Indies Lang ghenaemt ‘the Indian magpie, named Lang in the Indies,’ by this meaning a particular bird with a long beak- a hornbill, a bird native to the East Indies. A 1603 celestial globe by Willem Blaeu depicts it with a casque. It was interpreted on Chinese charts as Neaou Chuy ‘beak bird,’ and in England as ‘Brasilian Pye,’ while Johannes Kepler and Giovanni Battista Riccioli termed it Anser Americanus ‘American Goose,’ and Caesius as Pica Indica. Tucana and the nearby constellations Phoenix, Grus and Pavo are collectively called the ‘Southern Birds.’
[http://www.peoplesguidetothecosmos.com/constellations/tucana.htm]
[http://astropixels.com/constellations/charts/Tuc.html]
Tucana is not a prominent constellation as all of its stars are third magnitude or fainter. The layout of the brighter stars of Tucana has been likened to a kite. Within the constellation’s boundaries are around 80 stars brighter than an apparent magnitude of 7.
Alpha Tucanae is a binary star system. With an apparent visual magnitude of 2.86, it can be seen with the naked eye from the southern hemisphere. The distance to this system can be estimated as 200 light-years (61 parsecs). A cool star with a surface temperature of 4300 K, it is 424 times as luminous as the sun and 37 times its diameter. It is 2.5 to 3 times as massive. It is unclear what stage of evolution the star is in.
This is a spectroscopic binary, which means that the two stars have not been individually resolved using a telescope, but the presence of the companion has been inferred from measuring changes in the spectrum of the primary. The orbital period of the binary system is 4197.7 days (11.5 years). The primary component has a stellar classification of K3 III, which indicates it is a giant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence. It has the characteristic orange hue of a K-type star.
[https://en.wikipedia.org/wiki/Alpha_Tucanae]
Gamma Tucanae is a yellow-white sequence star of spectral type F1III and an apparent magnitude of 4.00, located around 75 light years from Earth. It also marks the toucan’s beak. This star has 1.55 times the mass of the Sun.
[https://en.wikipedia.org/wiki/Gamma_Tucanae]
Zeta Tucanae is a spectral class F9.5 main sequence star with an apparent magnitude of +4.23. Despite having a slightly lower mass, this star is more luminous than the Sun. It is approximately 28.0 light years from Earth. The composition and mass of this star are very similar to the Sun, with a slightly lower mass and an estimated age of three billion years. The solar-like qualities make it a target of interest for investigating the possible existence of a life-bearing planet. Based upon an excess emission of infrared radiation at 70 micrometres, this system is believed to have a debris disk. The disk is orbiting the star at a minimum radius of 2.3 astronomical units. It is radiating with a maximum temperature of 218 K. As of 2009, no planet has been discovered in orbit around this star.
[https://en.wikipedia.org/wiki/Zeta_Tucanae]
Epsilon Tucanae traditionally marks the toucan’s left leg. A B-type subgiant, it has a spectral type B9IV and an apparent magnitude of 4.49. It is approximately 373 light-years from Earth. It is around four times as massive as our Sun.
Beta, Delta and Kappa are multiple star systems containing six, two and four stars respectively. Located near the tail of the toucan, Beta Tucanae’s two brightest components, Beta1 and Beta2 are separated by an angle of 27 arcseconds and have apparent magnitudes of 4.4 and 4.5 respectively. They can be separated in small telescopes. A third star, Beta3 Tucanae, is separated by 10 arcminutes from the two, and able to be seen as a separate star with the unaided eye. Each star is itself a binary star, making six in total.
Lying in the southwestern corner of the constellation around 251 light-years away from Earth, Delta Tucanae consists of a blue-white primary contrasting with a yellowish companion. Delta Tucanae A is a main sequence star of spectral type B9.5V and an apparent magnitude of 4.49. The companion has an apparent magnitude of 9.3.
The Kappa Tucanae system shines with a combined apparent magnitude of 4.25, and is located around 68 light-years from the Solar System. The brighter component is a yellowish star, known as Kappa Tucanae A with an apparent magnitude of 5.33 and spectral type F6V, while the fainter lies 5 arcseconds to the northwest. Known as Kappa Tucanae B, it has an apparent magnitude of 7.58 and spectral type K1V. Five arcminutes to the northwest is a fainter star of apparent magnitude 7.24- actually a pair of orange main sequence stars of spectral types K2V and K3V, which can be seen individually as stars one arcsecond apart with a powerful telescope.
The second-brightest globular cluster in the sky after Omega Centauri, 47 Tucanae (NGC 104) lies just west of the Small Magellanic Cloud. Only 14,700 light-years distant from Earth, it is thought to be around 12 billion years old. Mostly composed of old, yellow stars, it does possess a contingent of blue stragglers, hot stars that are hypothesized to form from binary star mergers. 47 Tucanae has an apparent magnitude of 3.9, meaning that it is visible to the naked eye; it is a Shapley class III cluster, which means that it has a clearly defined nucleus:
47 Tuc: A great globular cluster of stars
Stars come in bunches. Of the over 200 globular star clusters that orbit the center of our Milky Way Galaxy, 47 Tucanae is the second brightest globular cluster (behind Omega Centauri). Light takes about 13,000 years to reach us from 47 Tuc which can be seen on the sky near the Small Magellanic Cloud in the southern constellation of Tucana. Also known as NGC 104, the dense cluster is made up of several million stars in a volume only about 120 light-years across. The cluster's red giant stars are particularly easy to see in this picture. The globular cluster is also home to exotic x-ray binary star systems.
[https://apod.nasa.gov/apod/ap080826.html]
NGC 362 is another globular cluster in Tucana with an apparent magnitude of 6.4, 27,700 light-years from Earth. Like neighboring 47 Tucanae, NGC 362 is a Shapley class III cluster and among the brightest globular clusters in the sky. Unusually for a globular cluster, its orbit takes it very close to the center of the Milky Way- approximately 3,000 light-years. It was discovered in the 1820s by James Dunlop. Its stars become visible at 180x magnification through a telescope:
Star cluster NGC 362 from Hubble
If our Sun were near the center of NGC 362, the night sky would glow like a jewel box of bright stars. Hundreds of stars would glow brighter than Sirius, and in many different colors. Although these stars could become part of breathtaking constellations and intricate folklore, it would be difficult for planetary inhabitants there to see- and hence understand- the greater universe beyond. NGC 362 is one of only about 170 globular clusters of stars that exist in our Milky Way Galaxy. This star cluster is one of the younger globulars, forming likely well after our Galaxy. NGC 362 can be found with the unaided eye nearly in front of the Small Magellanic Cloud, and angularly close to the second brightest globular cluster known, 47 Tucanae. The featured image was taken with the Hubble Space Telescope to help better understand how massive stars end up near the center of some globular clusters.
[https://apod.nasa.gov/apod/ap171011.html]
Located at the southern end of Tucana is the Small Magellanic Cloud:
Taken under the ‘wing’ of the Small Magellanic Cloud
The tip of the ‘wing’ of the Small Magellanic Cloud galaxy is dazzling in this new view from NASA’s Great Observatories. The Small Magellanic Cloud, or SMC, is a small galaxy about 200,000 light-years way that orbits our own Milky Way spiral galaxy.
The colors represent wavelengths of light across a broad spectrum. X-rays from NASA's Chandra X-ray Observatory are shown in purple; visible-light from NASA’s Hubble Space Telescope is colored red, green and blue; and infrared observations from NASA's Spitzer Space Telescope are also represented in red.
The spiral galaxy seen in the lower corner is actually behind this nebula. Other distant galaxies located hundreds of millions of light-years or more away can be seen sprinkled around the edge of the image.
The SMC is one of the Milky Way’s closest galactic neighbors. Even though it is a small, or so-called dwarf galaxy, the SMC is so bright that it is visible to the unaided eye from the Southern Hemisphere and near the equator. Many navigators, including Ferdinand Magellan who lends his name to the SMC, used it to help find their way across the oceans.
Modern astronomers are also interested in studying the SMC (and its cousin, the Large Magellanic Cloud), but for very different reasons. Because the SMC is so close and bright, it offers an opportunity to study phenomena that are difficult to examine in more distant galaxies. New Chandra data of the SMC have provided one such discovery: the first detection of X-ray emission from young stars, with masses similar to our sun, outside our Milky Way galaxy.
[http://www.nasa.gov/mission_pages/spitzer/multimedia/pia16884.html]
Though the Small Magellanic Cloud probably formed as a disk shape, tidal forces from the Milky Way have distorted it. Along with the Large Magellanic Cloud, it lies within the Magellanic Stream, a cloud of gas that connects the two galaxies:
The Magellanic Stream
In an astronomical version of the search for the source of the Nile, astronomers now have strong evidence for the origin of the Magellanic Stream. This composite image shows the long ribbon of gas, discovered at radio wavelengths in the 1970s, in pinkish hues against an optical all-sky view across the plane of our Milky Way galaxy. Both Large and Small Magellanic Clouds, dwarf satellite galaxies of the the Milky Way, are seen near the head of the stream at the right. Data from Hubble’s Cosmic Origins Spectrograph were used to explore abundances of elements along sightlines to quasars that intersect the stream. The results indicate that most of the stream’s material comes from the Small Magellanic Cloud. The Magellanic Stream is likely the result of gravitational tidal interactions between the two dwarf galaxies some 2 billion years ago, the Small Magellanic Cloud losing more material in the encounter because of its lower mass.
[http://apod.nasa.gov/apod/ap130815.html]
Tucana Dwarf by HST
[https://en.wikipedia.org/wiki/Tucana_Dwarf]
The Tucana Dwarf galaxy, which was discovered in 1990, is a dwarf spheroidal galaxy of type dE5 that is an isolated member of the Local Group. It is located 870 kiloparsecs (2,800 kly) from the Solar System and around 1,100 kiloparsecs (3,600 kly) from the barycentre of the Local Group- the second most remote of all member galaxies after the Sagittarius Dwarf Irregular Galaxy.
In 1998, part of the constellation was the subject of a two-week observation program by the Hubble Space Telescope, which resulted in the Hubble Deep Field South. The potential area to be covered needed to be at the poles of the telescope’s orbit for continuous observing:
A Deep Field in the Southern Sky
This new deep view of the cosmos is the sequel to the 1995 hit Hubble Space Telescope Deep Field. Billed as the Hubble Deep Field South, it was produced by pointing the space telescope toward a patch of sky in the southern constellation Tucana. Over a period of 10 days, many separate exposures were accumulated and combined to reveal progressively fainter galaxies. The original deep field was constructed by observing a piece of sky in the northern constellation Ursa Major. Both stare down 12 billion light-year long tunnels to far-off and still mysterious times when young galaxies inhabited an infant universe. Hubble Deep Field South observations were released to an enthusiastic audience on November 23, 1998.
[https://apod.nasa.gov/apod/ap981202.html]
SXP 1062 is a pulsar within a supernova remnant in the Small Magellanic Cloud:
SXP 1062: Celestial bauble intrigues astronomers
Astronomers have found evidence for a pulsar within a supernova remnant in the Small Magellanic Cloud. X-rays from Chandra and XMM-Newton show that the pulsar is rotating remarkably slowly- only once every 18 minutes. This object, known as SXP 1062, lies near a spectacular star-forming region of dust and gas (seen in optical light).
With the holiday season in full swing, a new image from an assembly of telescopes has revealed an unusual cosmic ornament. Data from NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton have been combined to discover a young pulsar in the remains of a supernova located in the Small Magellanic Cloud, or SMC. This would be the first definite time a pulsar, a spinning, ultra-dense star, has been found in a supernova remnant in the SMC, a small satellite galaxy to the Milky Way.
In this composite image, X-rays from Chandra and XMM-Newton have been colored blue and optical data from the Cerro Tololo Inter-American Observatory in Chile are colored red and green. The pulsar, known as SXP 1062, is the bright white source located on the right-hand side of the image in the middle of the diffuse blue emission inside a red shell. The diffuse X-rays and optical shell are both evidence for a supernova remnant surrounding the pulsar. The optical data also displays spectacular formations of gas and dust in a star-forming region on the left side of the image. A comparison of the Chandra image with optical images shows that the pulsar has a hot, massive companion.
Astronomers are interested in SXP 1062 because the Chandra and XMM-Newton data show that it is rotating unusually slowly- about once every 18 minutes. (In contrast, some pulsars are found to revolve multiple times per second, including most newly born pulsars.) This relatively leisurely pace of SXP 1062 makes it one of the slowest rotating X-ray pulsars in the SMC.
Two different teams of scientists have estimated that the supernova remnant around SXP 1062 is between 10,000 and 40,000 years old, as it appears in the image. This means that the pulsar is very young, from an astronomical perspective, since it was presumably formed in the same explosion that produced the supernova remnant. Therefore, assuming that it was born with rapid spin, it is a mystery why SXP 1062 has been able to slow down by so much, so quickly. Work has already begun on theoretical models to understand the evolution of this unusual object.
[http://chandra.harvard.edu/photo/2011/sxp1062/index.html]
[https://en.wikipedia.org/wiki/Tucana]
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