Melotte 15


Melotte 15 – Open Star Cluster in the IC 1805 Nebula

Melotte 15 is a very young star cluster in the IC 1805 nebula, also known as the Heart Nebula. It is comprised of OB stars, approximately 1.5 myr old and is one of the core clusters of the Cas OB6 stellar association.

Surrounding IC 1805 nebula glows bright in the red portion of the visible spectrum as the hydrogen is ionized by ultraviolet light from OB stars. This image captures this H II emission via narrowband filter centered at 656.3 nm wavelength. Clouds of neutral and atomic hydrogen appear as dark streaks and globules.

Image Data

Telescope: 10″ Aries f/15 Maksutov-Cassegrain on Astro-Physics 900GTO German Equatorial
Accessories: Moravian G1-0300 as Off-Axis Guider, 0.67X Astro-Physics CCD Telecompressor
Focal Length and Resolution: 2692 mm, 0.52″/pixel
Instrument: QSI 532wsg at -20 deg. C
Exposures: 3nm Narrowband [H II]: 6.75 hours [O III]: 6 hours, total: 12.75 hours
Filter(s): Astrodon Narrowband and Tru-Balance E-Series
Exposure Date: September 24 to October 2, 2011
Seeing, FWHM: Not Measured
Processing Software: MaximDL, PixInsight, Photoshop
Image Acquisition Software: MaximDL, TheSky6, CCDAutoPilot, FocusMax, PinPoint

Object Data

Constellation: Cassiopeia
Type: Open Star Cluster, type III 3 p n
Distance: 7,500 ly
Dimensions: 21′
Magnitude: ~ 6.5 (V)

Processing Procedure

LRGB Combination (R=[H II], G=[O III], B=[O III])
Histogram Transformation
Split to RGB
ATrousWaveletTransform on G and B channels (K-Sigma Noise Thresholding) to denoise
Generate Star Mask
ATrousWaveletTransform to bring details out (with noise suppression)
Resample to 1600px horizontal (resample mask too)
ATrousWaveletTransform to bring details out (with noise suppression)
Create Grayscale Layer via Desaturate
Overlay Grayscale as Luminosity over RGB Layer
Select stars, expand 5 pixels, feather 5 pixels, invert
Shadows 1%, Width 56%, Radius 300px, Highlights 0%, Midtone Contrast +30
Flatten, Levels (Subjective)
Noise Filter – selective low luminosity (low SNR) parts, Unsharp Mask



1995ApJ...454..151M The Initial Mass Function and Massive Star Evolution in the OB Associations of the Northern Milky Way Massey, Philip; Johnson, Kelsey E.; Degioia-Eastwood, Kathleen; Astrophysical Journal v.454, p.151 Nov 1995
2014ApJS..213....1T The Massive Star-Forming Regions Omnibus X-Ray Catalog Townsley, Leisa K.; Broos, Patrick S.; Garmire, Gordon P.; Bouwman, Jeroen; Povich, Matthew S.; Feigelson, Eric D.; Getman, Konstantin V.; Kuhn, Michael A.; The Astrophysical Journal Supplement, Volume 213, Issue 1, article id. 1, 25 pp. (2014). Jul 2014
1972A&AS....7..355M Photmetry of eleven young open star clusters Moffat, A. F. J.; Astronomy and Astrophysics Supplement, Vol. 7, p.355 Nov 1972
2007AJ....133.1092W Rotational Velocities for B0-B3 Stars in Seven Young Clusters: Further Study of the Relationship between Rotation Speed and Density in Star-Forming Regions Wolff, S. C.; Strom, S. E.; Dror, D.; Venn, K.; The Astronomical Journal, Volume 133, Issue 3, pp. 1092-1103. Mar 2007
1989AJ.....98..611G Reddening and polarimetric studies toward IC 1805 Guetter, Harry H.; Vrba, Frederick J.; Astronomical Journal (ISSN 0004-6256), vol. 98, Aug. 1989, p. 611-625, 745, 746. Aug 1989
2009A&A...502..937M Early-type stars in the young open cluster NGC 2244 and in the Monoceros OB2 association. I. The multiplicity of O-type stars Mahy, L.; Nazé, Y.; Rauw, G.; Gosset, E.; De Becker, M.; Sana, H.; Eenens, P.; Astronomy and Astrophysics, Volume 502, Issue 3, 2009, pp.937-950 Aug 2009
2006A&A...456.1121D Early-type stars in the young open cluster IC 1805. II. The probably single stars HD 15570 and HD 15629, and the massive binary/triple system HD 15558 De Becker, M.; Rauw, G.; Manfroid, J.; Eenens, P.; Astronomy and Astrophysics, Volume 456, Issue 3, September IV 2006, pp.1121-1130 Sep 2006
1965AJ.....70..806V Membership of the open cluster IC 1805. Vasilevskis, S.; Sanders, W. L.; van Altena, W. F.; Astronomical Journal, Vol. 70, p. 806 Dec 1965
2006A&A...454..201G Rotating elephant trunks Gahm, G. F.; Carlqvist, P.; Johansson, L. E. B.; Nikolić, S.; Astronomy and Astrophysics, Volume 454, Issue 1, July IV 2006, pp.201-212 Jul 2006
1970PASJ...22..277I Spectrographic Observations of IC 1805 Ishida, K.; Publications of the Astronomical Society of Japan, vol. 22, p.277 (1970). 1970

Other 110 records retrieved but not showed.

The original query on ADS is available HERE.
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