SHarpless 293-295 “Falls of Blue”

These spectacles of the universe Sh2-293 and SH2-295 look like blue waterfalls glistening and pouring down.

Imaged in LRGBHA with our PlaneWave CDK 24 at Observatorio El Sauce, Chile.

Image Processing: Mark Hanson

Description: Alexander Zaytsev

Data SWOS: Mazlin, Parker, Forman, Hanson

240 min Lum, 120 min for each RGB and 120 min HA

Enjoy, Mark & Alex

This wonderful and extensive description

by Alexander Zaytsev

The image is showing the region of sky off one of the wings of IC 2177 (Gum 2, RCW 1, Sh2-292, Seagull) [1] nebula located on the border of Monoceros and Canis Major constellations containing two HII regions (as shown on annotated version of the image in Fig. 1):

Sh2-295 (LBN 1035) [2] in the lower left corner of the image, with the bright central star V* FZ CMa (HD 52942, a spectroscopic binary) [3] associated with the reflection nebula VdB90a. The V* FZ CMa itself is surrounded by the reflection nebula GN 07.00.3 [4]. Another reflection nebula VdB90b sitting on the boundary of this HII region is excited by the BD-11 1761 [5] - a star situated in the wing of the Seagull nebula outside of the FOV. The distance estimate to Sh2-295 given in [6, 7] is 2.28 ± 0.65 kly while the distance to V* FZ CMa based on Gaia parallactic measurements is 3.33 ± 0.16 kly.
Sh2-293 (LBN 1030) [8] with bright central star HD 52721 (BD-11 1747, HIP 33868, GU CMa) [9] (a quadruple star system [10] with two other components identified as HD 52721A [11] and HD 5272B [12]) associated with reflection nebula VdB88 (upper right corner of the image). The distance estimate for Sh2-293 given in [6, 7] is 2.45 ± 0.65 kly while parallax based distance estimate to its main ionizing star HD 52721 using Hipparcos astrometric data [13, 14] is yielding 1.45 ± 0.77 kly with is still compatible with Sh2-293 distance estimate given a large systematic error on HD 52721 distance estimate (1.2 mas parallax error even after the reduction [13, 14]).

Both HII regions are ionized by stars belonging to the CMa OB1 star association [15, 16] containing the CMa R1 association of reflection nebulae spanning across the region of the sky 2.5 deg x 1.6 deg across [17, 18].

The CMa R1 is nested in the “CMa shell” likely created by a sequence of supernova explosions that happened 1- 6 Myr ago [19, 20]. Fig. 2 shows the annotated version of the image with parallax data (in units of mas) available from the Gaia DR3 XPSD DB [21, 22]. Taking the distance to the scene at about 3 kly, the horizontal edges of the FOV correspond to 32.3 ly and 24.4 ly of linear distance. The other components of Seagull nebula such as IC 2177 and NGC 2327 are located at a significantly larger distance of 3.65 - 3.80 kly, so both Sh2-293 and Sh2-295 may be overlapping structures with respect to that larger CMa R1 scene.

Great many compact neutral gas clouds can be identified on the background in the FOV: 32 molecular clouds from MWISP survey [23, 24] alone are in it, including [KKY2004] 6 molecular cloud [25] sitting on the right boundary of Sh2-295 HII region and likely responsible for the formation of the multilayer structure of the wall there. Numerous compact neutral gas clouds are also forming a rather complex structure of the wall of Sh2-293 HII region presented here in unprecedented level of details.