Celestial hemisphere:  Southern  ·  Constellation: Serpens (Ser)  ·  Contains:  60 Ser  ·  60 c Ser  ·  HD170493  ·  HD170601  ·  HD170857  ·  LBN 90  ·  Sh2-64  ·  The star c Ser
SH2-64 in the Eagle Rift, Los_Calvos
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SH2-64 in the Eagle Rift

SH2-64 in the Eagle Rift, Los_Calvos
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SH2-64 in the Eagle Rift

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Description

It is on a region that is not very imaged because it is not very bright that we have set our sights...

(Wikipedia) Sh2-64 (also known as Westerhout 40, W40 or RCW 174) is an emission nebula visible in the tail of the constellation Serpent. Although little known, it is one of the closest star-forming regions to the solar system. Sh2-64 is located in the eastern part of the constellation, about 3° northeast of the star η Serpentis and a very short angular distance from the star 60 Serpentis, with an apparent magnitude of 5.39. Its light filters through a slit in the large complex of dark nebulae that make up the Eagle Rift, to the point that no background star fields are observable nearby. Because of this filter, the nebula cannot be viewed optically with any amateur instrument. However, it can be identified in long-exposure photographs taken using appropriate filters.
The best time to observe it in the evening sky is between June and November. Being only 2° from the celestial equator, it can be observed indiscriminately from all populated regions of the Earth, remaining invisible only from the areas immediately surrounding the North Pole.
It is a large H II region that is part of an important star-forming region, associated with the bright radio source W40, from which high-mass stars originate. Despite this, due to its strong darkening by the Eagle Rift, it remained a very understudied region for years. The nebula receives ionizing radiation from some young, massive stars of spectral class B1V, designated W40 OS1a, W40 OS2a, and W40 OS3a, all surrounded by a dense protoplanetary disk1. Estimates of its distance are about 400 pc (∼1,300 al)2 or at most 600 parsecs (1,960 light-years)1. In both cases, the location of the nebula falls on the inner edge of Orion's arm, corresponding to the dense clouds of unlit dust that make up the Eagle Rift.X-ray studies conducted by the Chandra Space Telescope have identified 194 X-ray sources almost certainly associated with W40, coinciding with as many young stellar objects.
The pre-main sequence stars identified in this region number about 600 and are grouped together in a very young, open spherical cluster deeply immersed in the cloud gas and heavily obscured by the dust banks of the Rift. The age of the components of this cluster would not exceed one million years, although it may contain stars of different ages. In particular, 6 of its 8 most massive stars are thought to be part of a second, younger generation, leading to the hypothesis of an extension of the formation processes of high-mass stars3. Stellar components identified by X-rays have a mass greater than 0.2 M☉. Of these, 90% have a mass of less than 2 M and 7 have a mass of 10 M☉☉ or more. The most massive star is W40 OS2a, with a mass of 10 M3☉.
The three ionizing stars form a small OB association.Some of the most notable sources of infrared radiation in the region have been listed by IRAS and bear the initials IRAS 18288-0207 and IRAS 18288-01584. To these is added the source GLRAF 21775. The densest nucleus in the entire region coincides with a molecular cloud cataloged as TGU 279-P7.

There is a bit of reflection in the foreground, under the light part, which is difficult to bring out.
The image is in LHa-HaRGB (No signal is detected in Green and OIII)

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SH2-64 in the Eagle Rift, Los_Calvos