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Carbon Star - AW Cygni
A red giant whose spectrum is dominated by strong absorption bands of carbon-containing molecules. The Swan bands of C2 are especially prominent, with absorption by CN, CH, C3, SiC2, and C aII present to varying degrees, with often a strong sodium D line.
Carbon stars, also known as C stars, have carbon/oxygen ratios that are typically four to five times higher than those of normal red giants and show little trace of the light metal oxide bands that are the usual red giant hallmark. They resemble S stars in their relative proportion of heavy and light metals, but contain far more carbon in their upper layers. The carbon is likely the dredged-up ashes of nuclear helium burning in the stellar interior. Carbon stars lose a significant fraction of their total mass in the form of a stellar wind which ultimately enriches the interstellar medium – the source of material for future generations of stars.
Carbon stars were previously classified as stars of spectral type R (hotter, with surface temperatures of 4,000 to 5,000 K) and N (up to 10 times more luminous but cooler, with a temperature of about 3,000 K). They are typically associated with some circumstellar material in the form of sooty shells, disks, or clouds.
www.daviddarling.info/encyclopedia/C/carbon_star.html
Distance: ~32,615 light years, Magnitude Range: +7.1 to +8.5, Colour Index B-V: +3.9, Period: 340 Days, R.A. & DEC: 19 28 47 +46 02 38, Spectral Type: C4 (N3)
Image details: Date: 17th March 2016
R-Bessell Photometric Filter: 20 seconds x5 exposures, flat fielded, aligned and median combined
G-Bessell Photometric Filter: 39 seconds x5 exposures, flat fielded, aligned and median combined
B-Bessell Photometric Filter: 86 seconds x5 exposures, flat fielded, aligned and median combined
B-V-R folder images were then aligned and stacked to give Master B, V and R images; these were then colour combined in CCDSoft v5
Cherryvalley Observatory (MPC/IAU Code: I83)
CCD Operating Temperature: -37 Degrees Centigrade, Field of View: 46 x 37 arcmins, Pixel Array: 1280 x 1024Pixel Size: 16um x 16 um, Plate Scale: 2.17 arcsec/pixel, 0.2-m SCT+SBIG STL 1301E CCD, f/ratio: 7.6
Date: 17th March 2016
Carbon Star - AW Cygni
A red giant whose spectrum is dominated by strong absorption bands of carbon-containing molecules. The Swan bands of C2 are especially prominent, with absorption by CN, CH, C3, SiC2, and C aII present to varying degrees, with often a strong sodium D line.
Carbon stars, also known as C stars, have carbon/oxygen ratios that are typically four to five times higher than those of normal red giants and show little trace of the light metal oxide bands that are the usual red giant hallmark. They resemble S stars in their relative proportion of heavy and light metals, but contain far more carbon in their upper layers. The carbon is likely the dredged-up ashes of nuclear helium burning in the stellar interior. Carbon stars lose a significant fraction of their total mass in the form of a stellar wind which ultimately enriches the interstellar medium – the source of material for future generations of stars.
Carbon stars were previously classified as stars of spectral type R (hotter, with surface temperatures of 4,000 to 5,000 K) and N (up to 10 times more luminous but cooler, with a temperature of about 3,000 K). They are typically associated with some circumstellar material in the form of sooty shells, disks, or clouds.
www.daviddarling.info/encyclopedia/C/carbon_star.html
Distance: ~32,615 light years, Magnitude Range: +7.1 to +8.5, Colour Index B-V: +3.9, Period: 340 Days, R.A. & DEC: 19 28 47 +46 02 38, Spectral Type: C4 (N3)
Image details: Date: 17th March 2016
R-Bessell Photometric Filter: 20 seconds x5 exposures, flat fielded, aligned and median combined
G-Bessell Photometric Filter: 39 seconds x5 exposures, flat fielded, aligned and median combined
B-Bessell Photometric Filter: 86 seconds x5 exposures, flat fielded, aligned and median combined
B-V-R folder images were then aligned and stacked to give Master B, V and R images; these were then colour combined in CCDSoft v5
Cherryvalley Observatory (MPC/IAU Code: I83)
CCD Operating Temperature: -37 Degrees Centigrade, Field of View: 46 x 37 arcmins, Pixel Array: 1280 x 1024Pixel Size: 16um x 16 um, Plate Scale: 2.17 arcsec/pixel, 0.2-m SCT+SBIG STL 1301E CCD, f/ratio: 7.6
Date: 17th March 2016