Astronomy:Sh 2-174

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Sh 2-174
Nebula
Planetary Nebula
File:300px
Sh 2-174 imaged by Nicholas U. Mayall Telescope
Credit: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOIRLab/NSF/AURA)
Observation data: epoch
Right ascension 23h 45m 2.27s[1]
Declination+80° 56′ 59.6″[1]
Distance980[2] ly
DesignationsSH 2-174, LBN 598, PK 120+18 1, PN G120.3+18.3[1]
See also: Lists of nebulae

Sh 2-174 (also known as Valentine Rose Nebula) is a planetary nebula located in the constellation of Cepheus. It is one of the northernmost objects in the Sharpless catalog and has been the subject of debate regarding whether it is a planetary nebula interacting with the interstellar medium or an emission nebula ionized by a hot white dwarf.[3]

Discovery

Stewart Sharpless cataloged the object in 1959 as part of his Sharpless catalog of H II regions, based on red-sensitive photographic plates from the Palomar Observatory Sky Survey.[4] He described it as a faint irregular nebula with a maximum diameter of about 10 arcminutes.[4]

Observations

The white dwarf was catalogued as GD 561 (WD 2342+806).[5] It was first identified by American astronomer Henry L. Giclas in 1970.[6] In 1993, R. Napiwotzki and D. Schönberner's observation of GD 561 showed similarities to the central stars of other known planetary nebulae such as Sh 2-216 and the Helix Nebula.[7] In 1994, R.W. Tweedy and R. Napiwotzki confirmed the physical association between the planetary nebula and white dwarf GD 561 and found the white dwarf was outside the planetary nebula.[2]

References