Sh2-140 in Cepheus




© Velimir Popov & Emil Ivanov 2020
Size: 2000 px
Sh2-140 is an emission nebula in the constellation of Cepheus. It is part of the large star-forming region of the Cepheus molecular nebula complex. The nebula is located in the central-southern part of the constellation, about 5 ° north of the star ζ Cephei. It is located on the edge of a vast dark complex and can be taken in long exposure photographs on large amateur telescopes. Inside there is a group of young stars of ninth and tenth magnitudes, dominated by HD 211880, a white-blue star of main sequence of spectral class B0.5V with a magnitude of 7.74. The central region is completely invisible in the optical images, while from the near infrared images and in the radio waves it is evident the presence of a very concentrated cluster of stars.
Sh2-140 is an H II region located on the southwestern edge of the dark nebula LDN 1204, in the Cepheus Bubble, at a distance of about 900 parsecs (2900 light years) from the Sun. The star responsible for ionizing the nebula's gases is HD 211880 , a blue star on the main sequence; the temperature of the powders would be just 35 K, while its mass would be 600 M☉.
Several observations at multiple wavelengths were conducted on this nebula, centered above all in the bright region on the edge of LDN 1204 and on the infrared sources located behind it. The observations on the whole infrared band were conducted mainly in order to identify any young stars present in the region; as a result of these studies, a first catalog was prepared including all the young stellar objects of Sh2-140, consisting of three infrared sources, IRS 1, IRS 2 and IRS 3, to which two other sources were discovered which were later discovered . From the spectral indices of the first three sources it was deduced that they originate from a weak H II region ionized by photons from a single class B main sequence star.
From the observation of the protostar, however, a simplified model of the region was developed which was used to obtain the physical conditions of the dust and gases present here; the IRS 1 source appears surrounded by a dense disk of dust, illuminated in part by photons emerging from its polar regions together with the inner edge of a molecular gas envelope. The model developed from these observations is able to explain the diffuse distribution of light intensity; the blue color of the surrounding regions then implies the existence of a radiation field with relatively low temperatures,of ca900 K.

Image details:


Center of field RA 22:19:17 (h:m:s)
Center of field DE +63:16:38 (deg:m:s)
Size 75.6 x 57.9 (arcmin)
Pixel scale: 2.27 (arcsec/pixel)
Orientation: Up is 1.07 degrees E of N
Charts and image details obtained from
Optic(s): ASA 12" Astrograph @ f/3.6 (Newton)
Mount: ASA DDM85 Standard
Camera: SBIG STL 11000 M
Filters: Luminance, Red, Green, Blue, Astronomik filters
Dates/Times: 30.Oct.2011
Location: IRIDA Observatory, BG, longitude: E 24 44' 18", latitude: N 41 41' 42"
Exp. Details: L:6x10min;R:6x10 min, G:6x10 min, B:6x10 min; Ha:6x15. Bin 1 Total exp.time: 330min 5:30 hrs
More details: Dark and flat frames reduction
Processing: PixInsight / PS
Copyright: Velimir Popov and Emil Ivanov 2020. All Rights Reserved
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