Hemisphere:  Southern  ·  Constellation: Carina (Car)
RCW 58 : a Wolf-Rayet star in Carina, 



    
        

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RCW 58 : a Wolf-Rayet star in Carina

RCW 58 : a Wolf-Rayet star in Carina, 



    
        

            Los_Calvos
Powered byPixInsight

RCW 58 : a Wolf-Rayet star in Carina

Acquisition details

Dates:
Feb. 5, 2021 ·  Feb. 6, 2021 ·  Feb. 7, 2021 ·  Feb. 8, 2021 ·  Feb. 9, 2021
Frames:
Chroma Technology Chroma Blue: 16×300(1h 20′) -20°C bin 1×1
Chroma Technology Chroma Green: 17×300(1h 25′) -20°C bin 1×1
Chroma Technology Chroma Ha 3nm: 94×1200(31h 20′) -20°C bin 1×1
Chroma Technology Chroma OIII 3nm: 39×1200(13h) -20°C bin 1×1
Chroma Red: 10×300(50′) -20°C bin 1×1
Integration:
47h 55′
Darks:
51
Flats:
11
Bias:
200
Avg. Moon age:
25.09 days
Avg. Moon phase:
22.22%
Bortle Dark-Sky Scale:
1.00

RA center: 11h06m13s.924

DEC center: -65°3054.90

Pixel scale: 0.732 arcsec/pixel

Orientation: 1.063 degrees

Field radius: 0.580 degrees

More info:Open 

Resolution: 4040x4032

File size: 79.1 MB

Data source: Own remote observatory

Remote source: Observatorio El Sauce

Description

We continue to process our images in late (feb 2021), this object is a little atypic and not often imaged, in Carina : RCW 58



This beautiful E-type nebula, RCW 58, in the southern constellation of Carina, surrounds and originates from a special type of star, a Wolf-Rayet star, WR40 (HD 96548, WN8).The bright blue star in the middle of the nebula in the above image is WR40. The nebula is referred to as a ring nebula, due to its open appearance. It is elongated north-south 9′ x 5′ based upon the red hydrogen alpha (H-a) data, but the blue-green oxygen (OIII) data extends its width to about 8′ east-west, where north is up. The nebula is expanding at a rate of 87 km/s. It has an unusual appearance with knots and a radial pattern shown by the red H-a data.

These three dimensional bubbles appear as a ring in two dimensions, as seen in this image and represent the stellar ejecta contained in a wind blown bubble.

H alpha and OIII emissions from eight of the most well defined Wolf Rayet ring nebulae in the Galaxy reveal that in many cases the outermost edge of the OIII emission leads the H alpha emission. This suggests that these offsets, when present, are due to the shock from the Wolf Rayet bubble expanding into the circumstellar envelope

WR stars are huge, perhaps as large as 20 to 60+ solar masses. They lose mass as they evolve at an incredible rate, producing very strong solar winds. They are very hot with temperatures ranging from 30,000 to 200,000 Kelvin. There are about 500 of these stars cataloged in our Milky Way Galaxy. They give off a large amount of ultraviolet (UV) radiation that ionizes the surrounding nebula and makes it glow, allowing us to see it. Most of these WR stars are thought to progress to a supernova explosion

The spectroscopic study of emission lines of Hα, [N II], [O III] and [S II] in the WR ring nebula RCW 58 :

By combining high spectral resolution and signal-to-noise ratio with fine spatial sampling, we are able to clarify the complex kinematics of this wind-blown nebula which in previous data appeared chaotic. RCW 58 consists of a shell expanding at 87±3km s−1 from the central star and enveloping slower moving clumps of stellar ejecta, probably produced before the turn-on of the WR wind. We derive an upper bound to the age of the wind-blown shell of 3×104yr. Detailed maps of the different velocity components within the nebula, obtained by profile-fitting of the emission lines, are presented. In an earlier paper (Smith et al.) we suggested that observed UV absorption features arise in a ‘mass-loaded’ shocked stellar wind flow. We find that the expansion velocity of the shell is, as we expected on the basis of our proposed model, in very good agreement with that of the slowest moving absorbing gas observed at UV wavelengths. The linewidths in the shell are superthermal; it is unlikely they result from the superposition of multiple, unresolved components because of the high spatial resolution of the data. We therefore suggest that supersonic turbulence is present in the shell. The observed properties of the clumps, which load the stellar wind flowing past them by losing material to it, are discussed in the context of our model. Constraints on the clump masses imply that they are flattened but the observed velocity structures show that they are remarkably coherent. The velocities, abundances and dust content of the clumps suggest that the progenitor of the central WN8 star HD 96548 was a red supergiant

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RCW 58 : a Wolf-Rayet star in Carina, 



    
        

            Los_Calvos