Bruger:AstroOgier/Magellanske Skyer

De Magellanske Skyer er en fællesbetegnelse for Store magellanske Sky og Lille magellanske Sky, som er to satellitgalakser til Mælkevejsgalaksen. De er dermed ligesom Andromedagalaksen, Triangulumgalaksen og disses satellitgalakser medlem af den Lokale Hob af galakser. De er iøjnefaldende objekter på den sydlige himmelhalvkugle, men kan ikke ses fra Danmark. De bevæger sig i baner omkring Mælkevejsgalaksen, men om banen er elliptisk (lukket kredsløb) eller hyperbolsk (førstegangs besøgende) er uafklaret på grund af det korte tidsrum, man har kunnet observere dem i.

Data

Egennavn	Katalog- betegnelse	Galakse- type	Afstand lysår parsec	Diameter lysår parsec	Masse solmasser	Rektascension	Deklination	Visuel størrelsesklasse m_vis
Store magellanske Sky^[1]	ESO 56-115	SBm/Irr	163 000 ± 3600 pc 49 900 ± 1100 la^[2]	25 100 la 7700 pc	1·10¹⁰ M_☉	5^h 23^m 35^s	-69° 45′ 22″	0.9 mag
Lille magellanske Sky^[3]	NGC 292	Irr	≈ 209 000 la ≈ 64 000 pc	10100 la 3100 pc	2·10⁹ M_☉	0^h 52^m 45^s	-72° 49′ 43″	2.7 mag

Opdagelseshistorie

De to Magellanske Skyer har Oldtiden igennem været iøjnefaldende objekter for mennesker på den sydlige halvkugle. Den første bevarede omtale af den Store magellanske Sky findes hos den persiske astronom Al Sufi^[4], som i 964 i sit skrift Bogen om fiksstjerner betegner den Al Bakr, den Hvide Okse. Han bemærker, at den er usynlig set fra det nordlige Arabien, Baghdad og Irak (?), men kan ses i det sydligste Arabien ved Bab el-Mandeb-strædet på 12° 15′ nordlig bredde.

Skyerne blev formodentlig også omtalt af Amerigo Vespucci i et brev skrevet på hans tredie rejse omkring 1503-4 som en af "de tre Canopes, to lyse og en mørk"; de lyse menes at være de Magellanske Skyer, medens den mørke velsagtens er den mørke tåge Kulsækken.

Kilde: http://messier.obspm.fr/xtra/ngc/lmc.html

I 1600-tallet blev de omtalt af to italienske skribenter:

Peter Martyr d'Anghiera^[5]:

"Assecuti sunt Portugallenses alterius poli gradum quintum & quinquagesimum amplius, ubi punctum, circumeuntes quasdam nubeculas licet intueri, veluti in lactea via sparsos fulgores per universum coeli globum intra eius spatii latitudinem."
("Portugeserne nåede ud over den femoghalvtresindstyvende breddegraf fra den anden pol [den sydlige himmelpol], hvor man kan se nogle tåger, som kredser omkring punktet [den sydlige himmelpol], spredt væk fra Mælkevejen som lysende pletter rundt om hele himmelkuglen inden for dens rumlige udstrækning [dvs. tågerne synes at ligge i eller uden for Mælkevejens udstrækning på den sydlige himmel].

Andrea Corsali^[6]:

Han beretter, at hans skib passerede Kap det gode Håb ("the cape of Bona Speranza") og befandt sig på 37 graders sydlig bredde, hvorfra han observerede de Magellanske Skyer:

"Here we sawe a marueylous order of starres, so that in the parte of heauen contrary to owre northe pole, to know in what place and degree the south pole was, we tooke the day with the soonne, and obserued the nyght with the Astrolabie, and sawe manifestly twoo clowdes of reasonable bygnesse mouynge abowt the place of the pole continually now rysynge and nowe faulynge, so keepynge theyr continuall course in circular mouying, with a starre euer in the myddest which is turned abowt with them abowte xi degrees from the pole."
("Her så vi en storslået samling stjerner, så at i den del af himlen [som ligger] modsat vores nordlige [himmel]-pol, for at kende position og [bredde-]grad for den sydlige [himmel]-pol, [målte] vi om dagen ved hjælp af solen og observerede om natten ved hjælp af en astrolab, og [vi] så tydeligt to skyer af rimelig størrelse, der drejer sig rundt om positionen for den sydlige [himmel-]pol, bestandigt [veksle mellem] opstigning og nedgang, og således bibeholde deres fortsatte cirkelbevægelse altid med en stjerne midt [imellem dem], som med dem roterer omtrent 11 grader fra [den sydlige himmel]pol.)

Eventually, it was Magellan and his discovery expedition who brought them to our knowledge in 1519.

^[7] ^[8] ^[9] ^[10] ^[11]

Referencer

^ "NASA/IPAC Extragalactic Database". Data for Store magellanske Sky. Hentet 2025-01-22.
^ G. Pietrzyński; et al. (2013). "An eclipsing-binary distance to the Large Magellanic Cloud accurate to two per cent". nature. 495: 76-79. doi:10.1038/nature11878. {{cite journal}}: Eksplicit brug af et al. i: |forfatter= (hjælp)
^ "NASA/IPAC Extragalactic Database". Data for Lille magellanske Sky. Hentet 2025-01-22.
^ "Observatoire de Paris (Abd-al-Rahman Al Sufi)". Hentet 22 juli 2011.{{cite web}}: CS1-vedligeholdelse: Dato automatisk oversat (link)
^
For Peter Martyr d'Anghiera's mention of the Magellanic clouds, see:
- Petrus Martyr de Anghiera (1574) De rebus Oceanicis et Orbe Novo [Concerning the ocean and the new world] (Cologne, (Germany): Geruinum Calenium (Gerwin Calenius), 1574), decade 3, book 1, p. 217. (in Latin) From p. 217: "Assecuti sunt Portugallenses alterius poli gradum quintum & quinquagesimum amplius, ubi punctum, circumeuntes quasdam nubeculas licet intueri, veluti in lactea via sparsos fulgores per universum coeli globum intra eius spatii latitudinem." ("The Portuguese reached beyond the 55th degree of the other pole, where one may observe certain nebulae revolving around the point [i.e., the southern celestial pole], scattered in the Milky Way like luminous patches throughout the whole sphere of the sky, within the breadth of its extent." [That is, nebulae appear in or beside the Milky Way throughout its entire length in the southern sky.])
- Humboldt, Alexander von, with E.C. Otte and B.H. Paul, trans., Cosmos: A Sketch of a Physical Description of the Universe (London, England: Henry G. Bohn, 1852), vol. 4, pp. 340–341.
- For further details of – and other editions of – Peter Martyr d'Anghiera's book De Orbe Novo, see Wikipedia's article: Decades of the New World
^
From 1515 to 1517, Andrea Corsali sailed to the East Indies and China in a Portuguese ship. In 1516, Andrea Corsali sent a letter to Giuliano de' Medici, Duke of Nemours, mentioning the Magellanic clouds. This letter was translated into English by Richard Eden (c.1520–1576) and published in 1555. The relevant part of Corsali's letter (translated by Eden) appears in:
- Richard Eden, with Edward Arber, ed., The First Three English Books on America ... (Birmingham, England: 1885), "Of the pole antarike and the starres abowt the same ... ", p. 279. Corsali said that his ship had passed the Cape of Good Hope ("the cape of Bona Speranza") and was at 37 degrees south latitude when he observed the Magellanic clouds: "Here we sawe a marueylous order of starres, so that in the parte of heauen contrary to owre northe pole, to know in what place and degree the south pole was, we tooke the day with the soonne, and obserued the nyght with the Astrolabie, and sawe manifestly twoo clowdes of reasonable bygnesse mouynge abowt the place of the pole continually now rysynge and nowe faulynge, so keepynge theyr continuall course in circular mouying, with a starre euer in the myddest which is turned abowt with them abowte xi degrees from the pole." ("Here we saw a marvelous arrangement of stars, so that in the part of heaven [that is] opposite our north [celestial] pole, in order to know in what place and degree [of latitude] the south [celestial] pole was, we [measured our position during] the day using the sun, and observed [our position during] the night using an astrolabe, and saw clearly two clouds of reasonable bigness revolving around the location of the [southern celestial] pole, continually now rising and now falling, thus maintaining their continual course of circular motion, with a star always in the middle [between them], which revolves with them about 11 degrees from the [south celestial] pole.")
- See also: Kanas, Nick, Star Maps: History, Artistry, and Cartography, 2nd ed. (New York, New York: Springer Science + Business Media, 2012), § 4.3.2.2 Andreas Corsali, p. 118.
^ Pigafetta et al., with Lord Stanley of Alderley, trans., The First Voyage Round the World, by Magellan (London, England: Hakluyt Society, 1874), p. 66. From p. 66: "The antarctic pole is not so covered with stars as the arctic, for there are to be seen there many small stars congregated together, which are like to two clouds a little separated from one another, and a little dimmed..."
^ Bayer Johann (1603) Uranometria. Augsburg, (Germany): Christoph Mang. Star chart 49. The Large Magellanic Cloud (Nubecula major) appears below the chart's center and just above the fish Dorado; the Small Magellanic Cloud (Nubecula minor) appears to the left and below the chart's center and touches the right side of Hydrus the water snake.
^ Abbe, Cleveland (1867). "On the distribution of the nebulae in space". Monthly Notices of the Royal Astronomical Society (7 udgave). 27: 257-264. doi:10.1093/mnras/27.7.257a. From p. 262: "2. The Nebulae resolved and unresolved lie in general without [i.e., outside of] the Via Lactea [i.e., Milky Way], which is therefore essentially stellar. 3. The visible universe is composed of systems, of which the Via Lactea, the two Nubeculae [sic] [i.e., Magellanic Clouds], and the Nebulae, are individuals, and which are themselves composed of stars (either simple, multiple, or in clusters) and of gaseous bodies of both regular and irregular outlines."
^ Hertzsprung, E. (1913). "Über die räumliche Verteilung der Veränderlichen vom δ Cephei-Typus" [On the spatial distribution of variable [stars] of the δ Cepheid type]. Astronomische Nachrichten (tysk) (4692 udgave). 196: 201-208. Bibcode:1913AN....196..201H. From p. 204: "Zunächst ergibt sich eine Parallaxe der kleinen Magellanschen Wolke. ... und als außerhalb der Milchstraße liegend zu betrachten sein." (First, a parallax of the Small Magellanic Cloud follows. According to the 13 δ Cepheid variable [stars] that are treated above, the absolute brightness (the mean between the maximum and the minimum) of -7.3 m corresponds to a period of 6.6 days. Variable [stars] of the period 6.6 days have in the Small Magellanic Cloud a mean photographic star size of 14.5 m. If one assumes — according to the universal yellow color of the δ Cepheid variables — a color index of + 1.5 m, then the corresponding visual star size will equal 13.0 m. This consideration thus leads to a parallax p of the Small Magellanic Cloud, which is given by 5 log p = -7.3 - 13.0 = -20.3. One obtains p = 0.0001", corresponding to a distance of about 3000 light-years. Since the galactic latitude of the Small Magellanic Cloud amounts to about - 45°, then it would lie — according to the foregoing — about 2000 light-years from a plane [passing] through our Sun [and] lying parallel to the Milky Way and [it] would have to be regarded as lying outside the Milky Way.)
^ Leavitt, Henrietta S.; Pickering, Edward C. (March 3, 1912). "Periods of 25 Variable Stars in the Small Magellanic Cloud". Harvard College Observatory Circular no. 173.

[NED_LMC-1] "NASA/IPAC Extragalactic Database". Data for Store magellanske Sky. Hentet 2025-01-22.

[Pietrzyńskietal2013-2] G. Pietrzyński; et al. (2013). "An eclipsing-binary distance to the Large Magellanic Cloud accurate to two per cent". nature. 495: 76-79. doi:10.1038/nature11878. {{cite journal}}: Eksplicit brug af et al. i: |forfatter= (hjælp)

[NED_SMC-3] "NASA/IPAC Extragalactic Database". Data for Lille magellanske Sky. Hentet 2025-01-22.

[AlSufi-4] "Observatoire de Paris (Abd-al-Rahman Al Sufi)". Hentet 22 juli 2011.{{cite web}}: CS1-vedligeholdelse: Dato automatisk oversat (link)

[de_Anghiera-5] For Peter Martyr d'Anghiera's mention of the Magellanic clouds, see:
Petrus Martyr de Anghiera (1574) De rebus Oceanicis et Orbe Novo [Concerning the ocean and the new world] (Cologne, (Germany): Geruinum Calenium (Gerwin Calenius), 1574), decade 3, book 1, p. 217. (in Latin) From p. 217: "Assecuti sunt Portugallenses alterius poli gradum quintum & quinquagesimum amplius, ubi punctum, circumeuntes quasdam nubeculas licet intueri, veluti in lactea via sparsos fulgores per universum coeli globum intra eius spatii latitudinem." ("The Portuguese reached beyond the 55th degree of the other pole, where one may observe certain nebulae revolving around the point [i.e., the southern celestial pole], scattered in the Milky Way like luminous patches throughout the whole sphere of the sky, within the breadth of its extent." [That is, nebulae appear in or beside the Milky Way throughout its entire length in the southern sky.])

Humboldt, Alexander von, with E.C. Otte and B.H. Paul, trans., Cosmos: A Sketch of a Physical Description of the Universe (London, England: Henry G. Bohn, 1852), vol. 4, pp. 340–341.

For further details of – and other editions of – Peter Martyr d'Anghiera's book De Orbe Novo, see Wikipedia's article: Decades of the New World

[6] Petrus Martyr de Anghiera (1574) De rebus Oceanicis et Orbe Novo [Concerning the ocean and the new world] (Cologne, (Germany): Geruinum Calenium (Gerwin Calenius), 1574), decade 3, book 1, p. 217. (in Latin) From p. 217: "Assecuti sunt Portugallenses alterius poli gradum quintum & quinquagesimum amplius, ubi punctum, circumeuntes quasdam nubeculas licet intueri, veluti in lactea via sparsos fulgores per universum coeli globum intra eius spatii latitudinem." ("The Portuguese reached beyond the 55th degree of the other pole, where one may observe certain nebulae revolving around the point [i.e., the southern celestial pole], scattered in the Milky Way like luminous patches throughout the whole sphere of the sky, within the breadth of its extent." [That is, nebulae appear in or beside the Milky Way throughout its entire length in the southern sky.])

[7] Humboldt, Alexander von, with E.C. Otte and B.H. Paul, trans., Cosmos: A Sketch of a Physical Description of the Universe (London, England: Henry G. Bohn, 1852), vol. 4, pp. 340–341.

[8] For further details of – and other editions of – Peter Martyr d'Anghiera's book De Orbe Novo, see Wikipedia's article: Decades of the New World

[Corsali-6] From 1515 to 1517, Andrea Corsali sailed to the East Indies and China in a Portuguese ship. In 1516, Andrea Corsali sent a letter to Giuliano de' Medici, Duke of Nemours, mentioning the Magellanic clouds. This letter was translated into English by Richard Eden (c.1520–1576) and published in 1555. The relevant part of Corsali's letter (translated by Eden) appears in:
Richard Eden, with Edward Arber, ed., The First Three English Books on America ... (Birmingham, England: 1885), "Of the pole antarike and the starres abowt the same ... ", p. 279. Corsali said that his ship had passed the Cape of Good Hope ("the cape of Bona Speranza") and was at 37 degrees south latitude when he observed the Magellanic clouds: "Here we sawe a marueylous order of starres, so that in the parte of heauen contrary to owre northe pole, to know in what place and degree the south pole was, we tooke the day with the soonne, and obserued the nyght with the Astrolabie, and sawe manifestly twoo clowdes of reasonable bygnesse mouynge abowt the place of the pole continually now rysynge and nowe faulynge, so keepynge theyr continuall course in circular mouying, with a starre euer in the myddest which is turned abowt with them abowte xi degrees from the pole." ("Here we saw a marvelous arrangement of stars, so that in the part of heaven [that is] opposite our north [celestial] pole, in order to know in what place and degree [of latitude] the south [celestial] pole was, we [measured our position during] the day using the sun, and observed [our position during] the night using an astrolabe, and saw clearly two clouds of reasonable bigness revolving around the location of the [southern celestial] pole, continually now rising and now falling, thus maintaining their continual course of circular motion, with a star always in the middle [between them], which revolves with them about 11 degrees from the [south celestial] pole.")

See also: Kanas, Nick, Star Maps: History, Artistry, and Cartography, 2nd ed. (New York, New York: Springer Science + Business Media, 2012), § 4.3.2.2 Andreas Corsali, p. 118.

[10] Richard Eden, with Edward Arber, ed., The First Three English Books on America ... (Birmingham, England: 1885), "Of the pole antarike and the starres abowt the same ... ", p. 279. Corsali said that his ship had passed the Cape of Good Hope ("the cape of Bona Speranza") and was at 37 degrees south latitude when he observed the Magellanic clouds: "Here we sawe a marueylous order of starres, so that in the parte of heauen contrary to owre northe pole, to know in what place and degree the south pole was, we tooke the day with the soonne, and obserued the nyght with the Astrolabie, and sawe manifestly twoo clowdes of reasonable bygnesse mouynge abowt the place of the pole continually now rysynge and nowe faulynge, so keepynge theyr continuall course in circular mouying, with a starre euer in the myddest which is turned abowt with them abowte xi degrees from the pole." ("Here we saw a marvelous arrangement of stars, so that in the part of heaven [that is] opposite our north [celestial] pole, in order to know in what place and degree [of latitude] the south [celestial] pole was, we [measured our position during] the day using the sun, and observed [our position during] the night using an astrolabe, and saw clearly two clouds of reasonable bigness revolving around the location of the [southern celestial] pole, continually now rising and now falling, thus maintaining their continual course of circular motion, with a star always in the middle [between them], which revolves with them about 11 degrees from the [south celestial] pole.")

[11] See also: Kanas, Nick, Star Maps: History, Artistry, and Cartography, 2nd ed. (New York, New York: Springer Science + Business Media, 2012), § 4.3.2.2 Andreas Corsali, p. 118.

[Pigafetta-7] Pigafetta et al., with Lord Stanley of Alderley, trans., The First Voyage Round the World, by Magellan (London, England: Hakluyt Society, 1874), p. 66. From p. 66: "The antarctic pole is not so covered with stars as the arctic, for there are to be seen there many small stars congregated together, which are like to two clouds a little separated from one another, and a little dimmed..."

[Bayer-8] Bayer Johann (1603) Uranometria. Augsburg, (Germany): Christoph Mang. Star chart 49. The Large Magellanic Cloud (Nubecula major) appears below the chart's center and just above the fish Dorado; the Small Magellanic Cloud (Nubecula minor) appears to the left and below the chart's center and touches the right side of Hydrus the water snake.

[Abbe"-9] Abbe, Cleveland (1867). "On the distribution of the nebulae in space". Monthly Notices of the Royal Astronomical Society (7 udgave). 27: 257-264. doi:10.1093/mnras/27.7.257a. From p. 262: "2. The Nebulae resolved and unresolved lie in general without [i.e., outside of] the Via Lactea [i.e., Milky Way], which is therefore essentially stellar. 3. The visible universe is composed of systems, of which the Via Lactea, the two Nubeculae [sic] [i.e., Magellanic Clouds], and the Nebulae, are individuals, and which are themselves composed of stars (either simple, multiple, or in clusters) and of gaseous bodies of both regular and irregular outlines."

[Hertzsprung-10] Hertzsprung, E. (1913). "Über die räumliche Verteilung der Veränderlichen vom δ Cephei-Typus" [On the spatial distribution of variable [stars] of the δ Cepheid type]. Astronomische Nachrichten (tysk) (4692 udgave). 196: 201-208. Bibcode:1913AN....196..201H. From p. 204: "Zunächst ergibt sich eine Parallaxe der kleinen Magellanschen Wolke. ... und als außerhalb der Milchstraße liegend zu betrachten sein." (First, a parallax of the Small Magellanic Cloud follows. According to the 13 δ Cepheid variable [stars] that are treated above, the absolute brightness (the mean between the maximum and the minimum) of -7.3 m corresponds to a period of 6.6 days. Variable [stars] of the period 6.6 days have in the Small Magellanic Cloud a mean photographic star size of 14.5 m. If one assumes — according to the universal yellow color of the δ Cepheid variables — a color index of + 1.5 m, then the corresponding visual star size will equal 13.0 m. This consideration thus leads to a parallax p of the Small Magellanic Cloud, which is given by 5 log p = -7.3 - 13.0 = -20.3. One obtains p = 0.0001", corresponding to a distance of about 3000 light-years. Since the galactic latitude of the Small Magellanic Cloud amounts to about - 45°, then it would lie — according to the foregoing — about 2000 light-years from a plane [passing] through our Sun [and] lying parallel to the Milky Way and [it] would have to be regarded as lying outside the Milky Way.)

[Leavitt-11] Leavitt, Henrietta S.; Pickering, Edward C. (March 3, 1912). "Periods of 25 Variable Stars in the Small Magellanic Cloud". Harvard College Observatory Circular no. 173.

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