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IC 59, IC 63, Cassiopeia

IC 59, IC 63, Cassiopeia

530 mm f/5 16 hours, October 2012, Photograph

Gamma Cassiopeiae — The B0.5IVpe erratic variable subgiant star Gamma Cassiopeiae is a unique X-ray source with a spectrum composed of short term flares superimposed on a background with long term variations. A rapid rotation of 300 km/s combined with a high luminosity of 55,000 Lsolar has caused an ejection of matter that forms a hot circumstellar gaseous disc. The X-ray flux and optical emission variations are thought to be driven by a cyclical magnetic dynamo within the inner part of the circumstellar disc. Magnitude range +2.20 to +3.40, mass 19 Msolar, radius 14 Rsolar, temperature 30,900 K, distance 190 pc, age 8 Myr. From Robinson et al., "X-ray and Optical Variations in the Classical Be Star Gamma Cassiopeia: The Discovery of a Possible Magnetic Dynamo", The Astrophysical Journal, 575(1):435-448, 2002 August.

IC 59 and IC 63 — The nebulae IC 59 and IC 63 are collectively part of the larger 2 degree, 6.5 pc diameter HII region Sh 2-185 illuminated and ionized by Gamma Cassiopeiae. IC 59 is less dense and slightly cooler at 590 K than IC 63 at 630 K. The nebula spectra contain emission lines of polycyclic aromatic hydrocarbons (PAH). Neither nebula shows evidence of embedded star formation. The contrast in appearance between the nebulae is due to the difference in distances and variations in temperature and density. From Karr et al., "A Multiwavelength Study of IC63 and IC59", The Astronomical Journal, 129(2):954-968, 2005 February.

WR 2 — The Wolf-Rayet star WR 2 is the only spectral type WN2 star cataloged in our Galaxy. Its spectrum is dominated by recombination lines of nitrogen and helium formed by an optically thick stellar wind. The high velocity wind at 3,200 km/s from WR 2 and its progenitor has created a hot and highly evacuated bubble in the interstellar medium of size 22 by 32 pc. WR 2 is a member of the Cassiopeiae OB1 association. Magnitude +11.33, distance 2.5 kpc, age 1.2 Myr. From Arnal et al., "The Interstellar Medium Around Galactic WN Stars: WR 2, WR 128 and WR 151", The Astronomical Journal, 118(4):1798-1805, 1999 October.

OX Cas — OX Cas is a B2V+B2V main-sequence eclipsing binary system of the Algol type. Magnitude range +9.39 to +10.35, period 2.5 days, primary/secondary star mass 7/6 Msolar, radius 5/4 Rsolar, temperature 24,000/23,000 K, distance 2.1 kpc, age 8 Myr. From Crinklaw et al., "A Photometric Analysis of the Eclipsing Binary OX Cassiopeiae", The Astronomical Journal, 98(4):1418-1426, 1989 October.

NGC 381 — NGC 381 is an intermediate-age open cluster with a Trumpler class of III1m. The cluster appears to contain no giant stars. Distance 1.1 +/- 0.2 kpc, age 320 +/- 80 Myr. From Ann et al., "BOAO Photometric Survey of Galactic Open Clusters. II. Physical Parameters of 12 Open Clusters", The Astronomical Journal, 123(3):905-914, 2002 Feburary.

Coordinates: RA 1h 2.5m, Dec +61° 1’, PA +0° 53’
Field of view: 1° 56’ x 1° 28’
Image scale: 4.2” / pixel

Date: October 2012
Location: Santa Lucia Range, California
Exposure: 24 x 40 minutes (16 hours), binned 2 x 2 at -20° C

Zenith SQM: 21.1 mag / "²
Guiding error: 0.5" rms
Star FWHM: 4.2", histogram
Star eccentricity: 0.34
Camera noise: 14 e- rms
Background noise: 25 e- rms
Subframe location: 329 e-
Subframe scale: 53 e-

Telescope: Takahashi FSQ-106EDX 530 mm f/5
Camera: Quantum Scientific Imaging 683wsg
Filter: Astrodon H-alpha, 3 nm bandwidth
Focuser: Spike-a Bahtinov Mask
Guider: Santa Barbara Instrument Group ST-i
Flats: Alnitak Astrosystems Flat-Man
USB: Icron Ranger 2122, Moxa UPort 404
Mount: Takahashi EM-400 Temma2M
Acquisition: Diffraction Limited MaxIm DL, CCDAstro Temma, ASCOM Platform
Processing: Pleiades Astrophoto PixInsight, MathWorks MATLAB, IHRP Platform