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Форум » Досуг » Космос » NGC 2
NGC 2
ingvarr
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Дата: 26.10.2015, 11:27:28 | Сообщение № 1
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NGC 2 — спиральная галактика в созвездии Пегас.

Галактика была открыта ирландским астрономом Лоуренсом Парсонсом 20 августа 1873.

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ingvarr
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Дата: 11.09.2016, 13:47:07 | Сообщение № 2
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NGC 2 (= PGC 567)
Discovered (Aug 20, 1873) by Lawrence Parsons, 4th Earl of Rosse
A magnitude 14.2 spiral galaxy (type SABbc?) in Pegasus (RA 00 07 17.1, Dec +27 40 42)
Historical Identification: Per Dreyer, NGC 2 (= GC 6246, 4th Lord Rosse, 1860 RA 00 00 06, NPD 63 06.0) is "very faint, small, south of GC 1" (GC 1 being NGC 1). The position precesses to RA 00 07 17.8, Dec +27 40 46, within 0.2 arcmin of the center of the galaxy listed above, and the galaxy is south of NGC 1, so the identification is certain.
Historical Notes: GC 6246 is an addendum to Dreyer's 1877 Supplement to the GC, and the description and position in the NGC are exactly the same as in that publication. The Supplement also notes that (as shown in Lord Rosse's 1878 paper), the appearance and position of the nova was verified by an observation at Birr Castle on Oct 29, 1877.
Physical Information: Based on a recessional velocity of 7560 km/sec, a straightforward calculation indicates that NGC 2 is about 350 million light years away, in reasonable agreement with widely varying redshift-independent distance estimates of 260 to 400 million light years. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was about 340 million light years away at the time the light by which we see it was emitted, about 345 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of 1.0 by 0.45 arcmin, it is about 100 thousand light years across. Note: Although close in the sky (see the wide-field image of NGC 1), NGC 1 and 2 are at very different distances; if stars, they would be called an "optical double".

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