VBRC-7 Planetary Nebula

Also catalogued as Wray 16-191 and ESO 225-3

Wonderful Description from Sakib Rasool

Situated not too far from the more well known Shapley 1, the obscure planetary nebula VBRC 7 is much less known. Consisting of a circular shell with a size of about 2 arcminutes, it contains both Ha and OIII emission. Also catalogued as Wray 16-191 and ESO 225-3, it is located in the constellation of Norma. VBRC 7 is the last of the seven planetary nebulae to be catalogued by the astronomers Sidney van den Bergh and Rene Racine in 1973.

However deep Ha exposures reveal a large outer structure with a size of approximately 17x21 arcminutes. This structure was discovered by the Galactic Planetary Nebula Halo Survey (GPNHS) team in May 2016. This was first verified to exist in an image released by the Atacama Photographic Observatory in July 2017 and was the first image to show this outer Ha cloud: https://www.atacama-photographic-observatory.com/page_photo.php?id=79

https://www.atacama-photographic-observatory.com/page_photo.php?id=91

However, their widefield image only showed the brightest part to the left and a deeper followup was needed. An unreleased private Ha image taken by the amateur astrophotographer Mike Keith in April 2021 showed the full circular structure for the first time. This image was a serendipitous coincidence, which was the result of Mike's photographic exploration of obscure and mostly unphotographed southern planetary nebulae.

This new image processed by Mark Hanson is not only the third image to show this large outer Ha structure but for the first time it shows a previously unknown and unrecognised inner OIII halo! VBRC 7 represents the first target given to Mark to photograph after joining the GPNHS team in April 2026 following the excellent results obtained on the GPNHS halo discoveries around Longmore 8 and Longmore 5.

The large Ha structure surrounding VBRC 7 was first discovered by the Galactic Planetary Nebula Halo Survey (GPNHS) team in May 2016 and the smaller inner OIII halo was first discovered by the Galactic Planetary Nebula Halo Survey (GPNHS) team in May 2026 using this image, exactly 10 years later!

The nature of both extended outer structures are completely different. The large Ha cloud is likely to be an ISM-type halo, something that is found around other planetary nebulae such as NGC 3242 and HDW 2. This arises as UV radiation from the ionizing central star of the planetary nebula leaks out of the optically thin shell and happens to ionize any ambient unrelated material in the surrounding area. One of the largest of this category is the 8 degree halo around Abell 36, which was discovered by the professional astronomer Peter McCullough who also discovered a mostly undocumented ISM halo around Abell 15.

The inner OIII halo has a size of 3.5 arcminutes and is revealed for the first time in this image. This is very likely to be an AGB-type halo and represents matter ejected by the central star during its asymptotic giant branch (AGB) phase of its evolution. The AGB phase represents the endpoint of the evolutionary stage in the lifetime of low to intermediate mass stars, which is usually in the range of 0.5-8 solar masses. Stars that have entered the AGB phase experience heavy mass loss due to extreme radiation pressure. AGB haloes contain information about this mass loss history of the star and since they represent an earlier phase of evolution that precedes the ejection of the planetary nebula, not only are they older than the main planetary nebula shell but also much fainter with an extremely low surface brightness.

As a consequence of this, many haloes remain undetected due to lack of deep images. However, some of these unknown haloes are beginning to be revealed with long exposure amateur astrophotography with one of the most notable examples of recent times being the discovery of the spectacular halo surrounding IC 5148 by the amateur astrophotographer Don Goldman in 2013. It is likely that many more predominantly OIII haloes await discovery around planetary nebulae that have been unexplored photographically and currently lack deep images.

The presence of a large outer Ha ISM structure and inner blue OIII AGB halo makes VBRC 7 a previously unknown analogue to the much more well known NGC 6894. The Ha structures surrounding NGC 6894 have already been documented in the professional scientific literature but the OIII halo around NGC 6894 has not been studied by professional astronomers but has been revealed in amateur photographs.

Astrophotographers with an imaging setup with a field of view of at least 50 arcminutes wide could produce a dazzling image of two planetary nebulae in a single image, Shapley 1 and VBRC 7 together if an image is centred on the following coordinates: 15 53 16.45 -51 26 01.6

For astrophotographers who have a telescopic setup with a field of view of 1.2 degrees, a third planetary nebula could be included in an image centred directly on VBRC 7. Further to the left is PN G329.7+01.4, which has a size of 1 arcminute making a rare trio of planetary nebulae in a single image.

Imaged in RGBHa on a Planewave CDK 24 at Observatorio El Sauce, Chile. Taken Moravian C5. 36 x 300sec for each R-G-B, 72 x 600 for each Ha-OIII and 36x600 for SII

SWOS Group, Mazlin, Forman, Magill, Hawn, Stafforini, Hanson

Description from Sakib Rasool

Enjoy, Sakib, Mark and SWOS group.