9 of 12 photos
Thumbnails
 
Sh 2-140, LDN 1204, Cepheus

Sh 2-140, LDN 1204, Cepheus

530 mm f/5 20.7 hours, September 2012, Photograph

Sh 2-140 and LDN 1204 — The HII region Sh 2-140 and the molecular cloud LDN 1204 lie at a distance of 900 pc. Sh 2-140 is illuminated and ionized by the B0.5V main-sequence star HD 211880. The bright arc separating Sh 2-140 and LDN 1204 is a nearly edge-on ionization front. The front traces the outer surface of a portion of LDN 1204 that encases the compact infrared star cluster Sh 2-140IR. The cluster is completely obscured in visible light within LDN 1204. The cluster consists of about 50 protostars, the brightest of which have luminosities of several thousand Lsolar and masses of 5 to 10 Msolar. The material in LDN 1204 is primarily composed of polycyclic aromatic hydrocarbons (PAH), which glow along the ionization front. Extreme ultraviolet (EUV) light from HD 211880 is destroying these molecules and will eventually expose the embedded cluster. From Bally, et al., "The Fountains of Youth: Irradiated Breakout of Outflows in S140", The Astronomical Journal, 124(4):2152-2163, 2002 October.

Sh 2-140 outflows — Two outflows originating in the Sh 2-140 molecular cloud are breaking into the surrounding H II region. These outflows are visible in the rotated and inverted crop of the photograph along the ionization front shown here. The externally irradiated bow shock, HH 617, appears to be a counterflow associated the infrared cluster Sh 2-140IR. A second, larger bow shock, HH 616, indicates another outflow whose as yet undentified driving source lies southeast of Sh 2-140IR. The HH 616 outflow is surrounded by a fainter and larger concentric shell of H II streamers, labeled "Arch". This feature may indicate the extent of the region that has been influenced by the outflow. From Bally, et al., "The Fountains of Youth: Irradiated Breakout of Outflows in S140", The Astronomical Journal, 124(4):2152-2163, 2002 October.

Sh 2-145 — The extended HII region Sh 2-145 is ionized by several hot stars including the O9V main-sequence star HD 213023 and the O7.5V main-sequence star BD+62 2078. From Patel, "Origin and Evolution of the Cepheus Bubble", The Astrophysical Journal, 507(1):241-253, 1998 November.

Cepheus bubble — Sh 2-145, Sh 2-140 and LDN 1204 are located on the periphery of the Cepheus bubble. The bubble is a 10 degree, 120 pc diameter expanding ring-like structure of infrared emission and molecular clouds surrounding the Cepheus OB2 association. The total gas mass in the bubble is estimated to be 400,000 Msolar. The bubble likely originated 15 Myr ago with the formation of a cluster of massive, first generation stars within the open cluster NGC 7160 in a parent molecular cloud. Ionizing radiation and winds from these stars gave rise to a Strömgren sphere surrounded by a thin expanding shell that collected mass as it expanded. After 7 Myr gravitational instability lead to a fragmentation of the shell and the formation of a second generation of stars, those of the Cepheus OB2 association. Secondary expansion from these stars lead to a third generation of stars now being formed in the peripheral regions of the bubble, including Sh 2-140IR. From Patel, "Origin and Evolution of the Cepheus Bubble", The Astrophysical Journal, 507(1):241-253, 1998 November.

Coordinates: RA 22h 21.4m, Dec +63° 26’, PA +180° 29’
Field of view: 1° 56’ x 1° 28’
Image scale: 4.2” / pixel

Date: September 2012
Location: Monte Christo Range, Nevada
Exposure: 31 x 40 minutes (20.7 hours), binned 2 x 2 at -20° C

Zenith SQM: 21.4 mag / "²
Guiding error: 0.5" rms
Star FWHM: 4.4", histogram
Star eccentricity: 0.39
Camera noise: 14 e- rms
Background noise: 23 e- rms
Subframe location: 292 e-
Subframe scale: 66 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