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RCW 88
RCW 88 is an emission nebula in the southern constellation of Circinus that first appeared in the 1960 astronomical catalogue by Rodgers, Campbell & Whiteoak (RCW) of Hα-emission regions within the southern Milky Way.[4] Earlier observers, like James Wray in 1966, misclassified this as a likely 12.0v magnitude planetary nebula,[5] but later spectroscopic investigations revealed this as a diffuse nebulae.[6] RCW 88 was then to be identified by the infrared satellite IRAS as an HII region. Deep red images reveal that the inner nebula is divided into two parts by a central dark lane, and there is evidence of a larger halo of fainter nebulosity extending perhaps out to 10 arcmin. The RCW catalogue states the Hα image size is 3'×2.[4] RCW 88 is located about 3300 parsecs (10,000 light years)[1] from us, though other estimates place this at a closer 1800±300 pc.[7] or 1800±200 pc.[8] Assuming the former distance and the diameter as 5'-6' across, finds by simple trigonometry the true size subtends a minimum of 5±1 parsecs (16±3 light-years.) This small emission nebula shows a mean radial velocity of −18 km.s−1,[7] and is also a faint radio source that was identified by Lloyd Higgs in 1971.[3] Due to the large distance from us, astronomers have made few studies into the nature of RCW 88. Field StarThere is a 10.8v magnitude star identified as TYC 8702-56-1 positioned at RA : 15h 07m 25.1s Dec. : –57° 48' 32" (2000),[9] place 137 arc seconds southwest of the centre of the bright nebulosity.[10] It is unlikely that this star is associated with the nebulosity being probably a field star. References
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