RCW 15
Also called
Sh 2-310, Gum 8Coordinates: (237.25°, -6.5°)
[ Catalog | Explorer | SIMBAD ]
This vast nebula, one of the largest single HII regions known in the Milky Way, is ionised by two multiple star systems (Tau Canis Majoris and UW Canis Majoris) each made up of several O-class stars. This image shows only the brightest part of the enormous Sh 2-310 complex.
The intense radiation from the Tau Canis Majoris and UW Canis Majoris star systems has created a cavity in the molecular clouds at the centre of Sh 2-310, which is located beyond the upper right of the image.
Avedisova places Sh 2-310 in the star formation region SFR 237.25-6.50 with 62 components, including 4 masers, 14 infrared sources and the dark nebulae LDN 1660 and LDN 1664.
At least one scientific paper notes the "arrow-shaped bright rim" shown in this image. Perhaps Sh 2-310 should be known as the Arrowhead nebula?
The intense radiation from the Tau Canis Majoris and UW Canis Majoris star systems has created a cavity in the molecular clouds at the centre of Sh 2-310, which is located beyond the upper right of the image.
Avedisova places Sh 2-310 in the star formation region SFR 237.25-6.50 with 62 components, including 4 masers, 14 infrared sources and the dark nebulae LDN 1660 and LDN 1664.
At least one scientific paper notes the "arrow-shaped bright rim" shown in this image. Perhaps Sh 2-310 should be known as the Arrowhead nebula?
The extremely luminous red supergiant VY Canis Majoris is located in the direction of the bright rim. (This incredible star is green in this false colour image because of the infrared radiation emitted by the large dust cloud it ejects.)
You can see the full extent of the nebula in this false colour hydrogen-alpha image and this black and white SuperCOSMOS image. The F8Ia supergiant Wezen (Delta Canis Majoris) is visible towards the bottom of the nebula, but this is a foreground object.
Tau Canis Majoris, which may be one of the brightest stars in the Milky Way, is sometimes called the "Mexican jumping bean star", allegedly because of the way it moves around in the eyepiece of amateur telescopes. It is the hottest star within the NGC 2362 star cluster.
Tau and UW CMa are located in the centre of Sh 2-310. The O stars Tau CMa, UW CMa and the B1p star HD 58011 are all possible sources for the ionisation of Sh 2-310. The young red supergiant VY CMa is located near the bright rim of Sh 2-310. [1]
Radio parallax measurements of VY Canis Majoris give a distance estimate of 1140 (+110/-90) parsecs. [2]. This implies that either Sh 2-310 is closer than usually estimated or that VY CMa is a foreground object.
The green (infrared) star on the bright rim is VY CMa. The bright star (purplish) at the top of the rim is the B5III star HD 58612 (this has a visual magnitude of 5.781 and so presumably is much nearer than this nebula). [SIMBAD]
You can see the full extent of the nebula in this false colour hydrogen-alpha image and this black and white SuperCOSMOS image. The F8Ia supergiant Wezen (Delta Canis Majoris) is visible towards the bottom of the nebula, but this is a foreground object.
Tau Canis Majoris, which may be one of the brightest stars in the Milky Way, is sometimes called the "Mexican jumping bean star", allegedly because of the way it moves around in the eyepiece of amateur telescopes. It is the hottest star within the NGC 2362 star cluster.
Tau and UW CMa are located in the centre of Sh 2-310. The O stars Tau CMa, UW CMa and the B1p star HD 58011 are all possible sources for the ionisation of Sh 2-310. The young red supergiant VY CMa is located near the bright rim of Sh 2-310. [1]
Radio parallax measurements of VY Canis Majoris give a distance estimate of 1140 (+110/-90) parsecs. [2]. This implies that either Sh 2-310 is closer than usually estimated or that VY CMa is a foreground object.
The green (infrared) star on the bright rim is VY CMa. The bright star (purplish) at the top of the rim is the B5III star HD 58612 (this has a visual magnitude of 5.781 and so presumably is much nearer than this nebula). [SIMBAD]
Notes
1. ^ Lada, C. J. & Reid, M. J. (1978). "CO observations of a molecular cloud complex associated with the bright rim near VY Canis Majoris", The Astrophysical Journal, Vol. 219, 95-97. [1978ApJ...219...95L]
2. ^ 2008PASJ...60.1007C
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Most of the sources used to create these nebula descriptions are listed in the
notes section for each description. In some cases,
for example the Avedisova, Humphreys and Reed catalogs, the source is used extensively and is not listed in the
individual nebula descriptions. See this catalog overview
for more information on the catalogs and the general sources used
to create these descriptions and this introduction to HII regions
on the general history of this area of astronomy.
This image was created using the POSS-II/UKSTU data of the Digitized Sky Survey and SuperCOSMOS using the process described here.
According to my correspondence with the Royal Observatory Edinburgh and the Space Telescope Science Institute, I am allowed to use the POSS-II/UKSTU data to create and display images for non-commercial purposes so long as I include this fine print for the SuperCOSMOS data:
Use of these images is courtesy of the UK Schmidt Telescope (copyright in which is owned by the Particle Physics and Astronomy Research Council of the UK and the Anglo-Australian Telescope Board) and the Southern Sky Survey as created by the SuperCOSMOS measuring machine and are reproduced here with permission from the Royal Observatory Edinburgh.
and this acknowledgement taken from the DSS site:
The Digitized Sky Surveys were produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions.
The Second Palomar Observatory Sky Survey (POSS-II) was made by the California Institute of Technology with funds from the National Science Foundation, the National Geographic Society, the Sloan Foundation, the Samuel Oschin Foundation, and the Eastman Kodak Corporation.
The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council (later the UK Particle Physics and Astronomy Research Council), until 1988 June, and thereafter by the Anglo-Australian Observatory. The blue plates of the southern Sky Atlas and its Equatorial Extension (together known as the SERC-J), as well as the Equatorial Red (ER), and the Second Epoch [red] Survey (SES) were all taken with the UK Schmidt.
The "Second Epoch Survey" of the southern sky was made by the Anglo-Australian Observatory (AAO) with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the ST ScI. The digitized images are copyright ? 1993-5 by the Anglo-Australian Observatory Board, and are distributed herein by agreement.
The "Equatorial Red Atlas" of the southern sky was made with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the ST ScI. The digitized images are copyright ? 1992-5, jointly by the UK SERC/PPARC (Particle Physics and Astronomy Research Council, formerly Science and Engineering Research Council) and the Anglo-Australian Telescope Board, and are distributed herein by agreement.
The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright ? 1993-1995 by the California Institute of Technology and are distributed herein by agreement. The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright ? 1993-1995 by the California Institute of Technology and are distributed herein by agreement.