Sh 2-27

Sharpless 2-27
Emission nebula
H II region
	Sh 2-27 (pink) embedded within molecular clouds (green and blue), imaged by the Northern Sky Narrowband Survey.
Observation data: J2000 epoch
Right ascension	16h 35m 56s
Declination	−12° 43′ 05″
Distance	440 ly
Apparent magnitude (V)	17.3
Apparent dimensions (V)	10° x 15°
Constellation	Ophiuchus
Physical characteristics
Radius	78 ly
Dimensions	480' x 480'
Designations	LBN 24, Gum 73, Cobold Nebula, Zeta Ophiuchi Nebula
	See also: Lists of nebulae

Sh 2-27 (also known as the Cobold Nebula or the Zeta Ophiuchi Nebula), is an emission nebula in the constellation Ophiuchus. It is ionized by the star Zeta Ophiuchi, which lies near its center. The star is a runaway that produces a notable bow shock.^[6]

The nebula is embedded within the Rho Ophiuchi cloud complex and can be classified as an H II region. Its distance of only about 440 light-years, determined from Gaia parallax measurements of Zeta Ophiuchi ^[2], makes it one of the closest known emission nebulae. This proximity is also the reason for its large apparent size of approximately 15° × 10°, even though the nebula itself is relatively faint.

References

↑ "SIMBAD query result".
1 2 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
↑ "Sharpless (Sh2) - Astrobasics". 13 September 2022.
↑ "Sharpless 27".
↑ "CCD Images of the Sharpless Catalog".
↑ "Sh 2-27".

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[1] "SIMBAD query result".

[GaiaDR3-2] 1 2 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[3] "Sharpless (Sh2) - Astrobasics". 13 September 2022.

[4] "Sharpless 27".

[5] "CCD Images of the Sharpless Catalog".

[6] "Sh 2-27".

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v t e Gum Catalog
Colin Stanley Gum
Gum 1 Gum 2 Gum 3 Gum 4 Gum 5 Gum 6 Gum 7 Gum 8 Gum 9 Gum 10 Gum 12 Gum 13 Gum 14 Gum 15 Gum 16 Gum 17 Gum 18 Gum 19 Gum 20 Gum 21 Gum 22 Gum 23 Gum 24 Gum 25 Gum 26 Gum 27 Gum 28 Gum 29 Gum 30 Gum 31 Gum 32 Gum 33 Gum 34 Gum 35 Gum 36 Gum 37 Gum 38 Gum 39 Gum 40 Gum 41 Gum 42 Gum 43 Gum 44 Gum 45 Gum 46 Gum 47 Gum 48 Gum 49 Gum 50 Gum 51 Gum 52 Gum 53 Gum 54 Gum 55 Gum 56 Gum 57 Gum 58 Gum 59 Gum 60 Gum 61 Gum 62 Gum 63 Gum 64 Gum 65 Gum 66 Gum 67 Gum 68 Gum 69 Gum 70 Gum 71 Gum 72 Gum 73 Gum 74 Gum 75 Gum 76 Gum 77 Gum 78 Gum 79 Gum 80 Gum 81 Gum 82 Gum 83 Gum 84 Gum 85
See also: Gum Nebula, RCW Catalogue