View source for RCW 88

{{Sky|15|07|08|-|57|48.3|0}}
{{ Planetary nebula |
| image = [[File:Red Cocoon Harbours Young Stars.jpg|300px]]
| caption = Star-forming region RCW 88 taken with the<br>
EFOSC2 instrument on [[ESO]]’s New Technology Telescope.<ref name=eso>{{cite news|title=Red Cocoon Harbours Young Stars|url=http://www.eso.org/public/images/potw1231a/|accessdate=30 July 2012|newspaper=ESO Picture of the Week}}</ref>
| name = RCW 88
| type = [[H II region]]
| epoch = [[J2000]]
| ra = {{RA|15|07|08}}<ref name=simbad>{{cite simbad|title=RCW 88|accessdate=25 February 2017}}</ref>
| dec = {{DEC|-57|48.3|0}}<ref name=simbad />
| dist_ly = 10.000
| appmag_v =12.0
| size_v = c. 5'-6'
| constellation  = Circinus
| radius_ly = c.16±3
| absmag_v =
| notes =
| names = PK 320+00.2, WRAY 16-166, WRAY 16-167, PN ARO 527,<ref name=simbad /> ARO 146<ref name=Higgs1971 />
}}
'''RCW 88''' is an [[emission nebula]] in the southern [[constellation]] of [[Circinus]] that first appeared in the 1960 [[astronomical catalog]]ue by Rodgers, Campbell & Whiteoak ([[RCW Catalogue|RCW]]) of [[Hα]]-emission [[H II region|regions]] within the southern [[Milky Way]].<ref name=RCW1960>{{Citation
|last1=Rodgers
|first1=A. W.
|last2=Campbell
|first2=C. T.
|last3=Whiteoak
|first3=J. B.
|title=A catalogue of Hα-emission regions in the southern Milky Way
|journal=[[Monthly Notices of the Royal Astronomical Society]]
|volume=121
|issue=1
|date=1960
|pages=103–110
|ref=rcw1960
|bibcode = 1960MNRAS.121..103R
|doi=10.1093/mnras/121.1.103|doi-access=free
}}</ref> Earlier observers, like James Wray in 1966, misclassified this as a likely 12.0v magnitude [[planetary nebula]],<ref name=Wray1966>{{cite thesis
|title=A Study of Hα-emission Objects in the Southern Milky Way
|date=25 February 2017
|last=Wray
|first=J.D.
|bibcode=1966PhDT.........3W
|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1966PhDT.........3W&db_key=AST&nosetcookie=1}}
</ref> but later spectroscopic investigations revealed this as a diffuse nebulae.<ref name="Acker1987">{{cite journal
|last=Acker
|first=A.
|author2=Chopinet, M.
|author3=Pottasch, S.R.
|author4=Stenholm, B.
|date=1987
|title=Misclassified planetary nebula
|journal=Astronomy and Astrophysics Supplement Series
|volume=71
|issue=1
|pages=163–175
|doi=
|bibcode=1987A&AS...71..163A}}</ref> 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.<ref name=RCW1960 />
RCW 88 is located about 3300 parsecs (10,000 light years)<ref name=eso /> from us, though other estimates place this at a closer 1800±300 pc.<ref name="Avedisova1989">{{cite journal
|last1=Avedisova
|first1=V.S.
|last2=Palous
|first2=J.
|date=1989
|title=Kinematics of star forming regions
|journal=Bulletin Astronomical Institutes of Czechoslovakia
|volume=40
|issue=1
|pages=42–52
|doi=
|bibcode=1989BAICz..40...42A}}</ref> or 1800±200 pc.<ref name="Avedisova1984">{{cite journal
|last1=Avedisova
|first1=V.S.
|last2=Kondratenko
|first2=G.I.
|date=1984
|title=Exciting stars and the distances of the diffuse nebulae
|journal=Nauchnye Informatsii
|volume=56
|pages=49
|doi=
|bibcode=1984NInfo..56...59A}}</ref> Assuming the former distance and the diameter as 5'-6' across, finds by simple trigonometry the true size subtends a minimum of 5±1 [[parsec]]s (16±3 light-years.)  This small emission nebula shows a mean radial velocity of −18&nbsp;km.s<sup>−1</sup>,<ref name=Avedisova1989  /> and is also a faint radio source that was identified by Lloyd Higgs in 1971.<ref name="Higgs1971">{{cite journal
|last1=Higgs
|first1=L.A.
|date=1971
|title=Catalog of radio observations of planetary nebulae, related optical data.
|journal=Publications of the Astrophysics Branch
|volume=1
|pages=1
|doi=
|bibcode=1971PAB.....1....1H}}</ref> Due to the large distance from us, astronomers have made few studies into the nature of RCW 88.
==Field Star==
There is a 10.8v magnitude star identified as TYC 8702-56-1 positioned at [[Right ascension|RA]] : 15h 07m 25.1s [[Declination|Dec.]] : –57° 48' 32" (2000),<ref name=simbad1>{{cite web| title=Search results for TYC 870-56-1 88|url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%407688161&Name=TYC%208702-56-1&submit=submit|work=Astronomical Database|publisher=SIMBAD|accessdate=25 February 2017}}</ref> place 137 arc seconds southwest of the centre of the bright nebulosity.<ref name=simbad2>{{cite web|title=Search results for TYC 870-56-1 88|url=http://simbad.u-strasbg.fr/simbad/sim-coo?Coord=15+07+08-57+48.3&CooFrame=ICRS&CooEqui=2000.0&CooEpoch=J2000&Radius.unit=arcmin&submit=query+around&Radius=3|work=Astronomical Database|publisher=SIMBAD|accessdate=25 February 2017}}</ref> It is unlikely that this star is associated with the nebulosity being probably a field star.
==References==
{{reflist}}
{{RCW}}
[[Category:Emission nebulae]]
[[Category:Circinus]]
[[Category:Star-forming regions]]
{{Circinus}}