Picture of the Month for 2025

• August 2025 - Picture of the Month

  The Spare Tyre Nebula (IC 5148) in Grus

  

  Rather than star formation, I've decided to bring you an image of star destruction for a change. This is IC 5148 in Grus, one of the fastest expanding planetary nebulae of which we're aware that lies about 4,200 light-years (1.3 kpc is the GAIA distance to the central star) away in the southern constellation of Grus. As is so often the case, there were multiple independent discoveries which have resulted in two designations, IC 5148 and IC 5150, for this object.

  The beautiful patterns and the extended halo in this image are the result of expanding and interacting shells of gas. They're ionised by that tiny blue-white dot in the centre, a white dwarf star with an effective temperature of around 130,000K. It's radiation pressure is sufficient to clear the nearby space of gas, thus allowing us to see it despite being only 16^th magnitude. The progenitor star, which was the source for all of this material, would've been relatively ordinary at around 1.5 solar masses.

  Although this excellent image was taken by one half of the International Gemini Observatory, there are a small number of images of IC 5148 by amateurs on the web. Certainly worth mentioning, and a look, we have one by Steve Crouch in Australia and another taken by Capella Observatory from Namibia back in 2003. Both of these images show quite a lot of detail, but it's evident that this is not an object that gets much interest. That's probably because of its location just below the celestial equator and relatively small size, about 2 arc-minutes in diameter.

  Reference

  1. Planetary nebula IC 5148 and its ionized halo, D. Barría, S. Kimeswenger, W. Kausch, D. S. Goldman, Astronomy & Astrophysics 620 (2018) A84, DOI: 10.1051/0004-6361/201833981 (Accessed 29 July 2025).

  James Whinfrey - Website Administrator.

• July 2025 - Picture of the Month

  Emission nebula Sh2-106 in Cygnus

  

  I've chosen a wonderful image of an object from Stewart Sharpless that's high in northern skies this month: Sh2-106 in his catalogue (aka the Celestial Snow Angel). This H-II region lies about 2,000 light-years from us in the constellation of Cygnus and was formed only 3,500 years ago from its parent molecular cloud.

  Sh2-106 is an emission nebula that's ionised by a 15 solar mass O8 type star, S106 IRS 4 (Infrared Source 4), hidden at it's heart in the centre of this image. It's bipolar hourglass shape makes this object look like a planetary nebula, and it's due to a ring of dust and gas in orbit around IRS 4 limiting local radial expansion.

  I particularly like the rippled texture of the nebula's "wings" which is caused by interaction between the high velocity outflows and the surrounding interstellar medium.

  At the other end of the stellar scale, studies of Sh2-106 in the infrared wavelength have revealed hundreds of brown dwarf stars that weight less than 0.1 solar masses and as a result have remained sub-stellar: a cluster of brown dwarves, not massive enough to fuse hydrogen.

  James Whinfrey - Website Administrator.

• June 2025 - Picture of the Month

  NGC6188 (Rim Nebula) in Ara

  

  It must be obvious by now that I've a fondness for dust and star formation. So there should be little surprise at this fabulous image of another region of the night sky that's made for astrophotography.

  NGC 6188 (RCW 108) is an emission nebula sculpted from the edge of a large molecular cloud by the massive stars of the Ara OB1a association, many of which can be found in nearby NGC 6193. A particularly rare and massive star is embedded in the centre of NGC 6164 (RCW 108) on the left side of this image. We're looking at a structure that appears very like a planetary nebula, but it's all created by the radiation from this O-type star, HD 148937, a supernova in the making. Supernovae probably had a lot to do with the structure of NGC 6193 itself, and possibly the initiation of the star formation across this region.

  All of this lies some 4,000 light-years from us, although northern observers will have to use a remote telescope in order to capture this object, or travel south just as Suzanne did. I'll conclude this month with some words from Suzanne's journal of that trip.

  This image of NGC6188 Rim Nebula (a.k.a. The Fighting Dragons of Ara) was captured during my first (to be annual - I just returned in early April 2025 from my second) trip to image from the Atacama Desert in Northern Chile. It was the most amazing trip, in all respects!

  I stayed at the San Pedro de Atacama Celestial Explorations (SPACE) Atacama Lodge…a magical place, whose owner Alain Maury knows the Southern Hemisphere skies like the back of his hand. During that trip, I had six nights of dark, clear skies – something I have never experienced! As a matter of fact, I ran out of preplanned targets, never daring to imagine that I would be able to image every night of the trip!

  I'm very honored to have been selected as the Webb Deep-Sky Society's Picture of the Month. This image also won 1^st prize in the 2024 Astronomical League’s Williamina Fleming Imaging Award competition…dark skies really do make a huge difference!

  James Whinfrey - Website Administrator.

• The star-forming nebula CB130-3 in Serpens Cauda

  May 2025 - Picture of the Month

  

  I had an amateur image lined up for this month, honest. Unfortunately I wasn't able to get the necessary permission to use it. It was a wonderful image of bright and dark nebulae, but now I found myself in need of a professional image as a back-up, and I wanted to stay with the theme.

  So this is what I came up with, it's an image of a dense star forming core, CB 130-3, which is about 1½° west of η Serpentis, and is most easily found by looking for LDN 507. I love that warm glow coming from inside the densest region of this nebula where the core is collapsing into a new star.

  On most of the deep-sky surveys this region is almost entirely blank, as you might expect for dark nebulae, while this HST image is clearly anything but. The contrast is can be clearly seen using the online ESASky tool where I can overlay this image on the PanSTARRS DR1 Survey. Best of all, it's possible to fade the image out to see a few of the brighter stars. The differences in density between regions in this nebulae can just be discerned in the sky survey with the help of this tool.

  James Whinfrey - Website Administrator.

• April 2025 - Picture of the Month

  Supernova remnant ESO 217-25 in Centaurus

  

  I've chosen a supernova remnant (SNR) in the southern constellation of Centaurus this April. I think that this is a fascinating structure, and Martin's done well to catch so much detail. There are relatively few images of it around.

  It's also an elusive target that isn't easy to tease out of many catalogue searches. As far as I can tell, ESO 217-25 designation is mainly used in amateur circles, alongside others like the Mermaid nebula or the Betta Fish nebula, whilst the designation of G296.5+10 more common for professional astronomers, with whom it also goes by PKS 1209-51/52.

  Either way, there's been some recent research interest in this object that sits roughly halfway between δ Cen and ρ Cen. This image appears to show the northern half of the SNR. The whole SNR is axially symmetric in the radio band and contains a compact X-ray source within it's bounds, which is probably a neutron star formed in the supernova event.

  The SNR and the neutron star lie around 14 kpc (4500 light-years) from us on the Carina Arm of the Milky Way. It's estimated to be about 14,000 years old given its mean diameter of 31 pc (101 light-years).

  ESO 217-25 is a large object, at least in the radio it's 90'×65', but I couldn't find a good visual estimate as I'd guess it's not easy to see. The Digitized Sky Survey (DSS) shows it as barely a shadow, but based on that I'd estimate that this image has a width of about 26 arc-minutes.

  James Whinfrey - Website Administrator.

• March 2025 - Picture of the Month

  Open cluster RCW 38 in Vela

  

  RCW 38 lies about 5,500 light-years away in the direction of Vela. It comprises a large and young open star cluster embedded within a nebula of dust and gas from which it formed, probably less than a million years ago. There are thousands of stars in this cluster, of which about 20 are huge O-type stars destined to become supernovae, and most of them are hidden within the nebula.

  I'm guessing that you've probably spotted that this isn't an amateur image, but I have my reasons.

  The European Southern Observatory (ESO) have captured a visible light image of RCW 38 in the past, but I've chosen this one because it was release last month and, most importantly, it's in the infrared so we can see far more stars in this wide field of view. If you'd like to compare the visible and infrared view then ESO have a fantastic slider on their website.

  Of course if it's the stars of RCW 38 itself that you're particularly interested in seeing, then ESO pointed another of their instruments, the HAWK-I camera, at this target for a close look a few years ago.

  

  So I've really got two Pictures of the Month and both are in the infrared spectrum, which is outside of the amateur sphere, at least I think that it is.

  James Whinfrey - Website Administrator.

• Interacting galaxies NGC 2207 and IC 2163 in Canis Major

  February 2025 - Picture of the Month

  

  Unfortunately I didn't manage to get permission to use the image I'd originally hoped to feature, perhaps that object will appear another time. But this image of a pair of merging galaxies from the James Webb Space Telescope (JWST) using its mid-infrared MIRI instrument isn't a bad alternative, is it?

  The Hubble Space Telescope (HST) has previously imaged NGC 2207 and IC 2163 with wonderful results, but this infrared image strips away the obscuring layers of dust and gas to reveal the extent of the star formation in these two galaxies. I think that this lends this image a skeletal feel around the galactic cores, especially when compared with the outrageously colourful HST version.

  It's my understanding that the "senior" partner here is NGC 2207 on the right, and also in the foreground, which has just started the process of stripping the gas from IC 2163 in the upper left. The JWST image above shows the position of bright new star clusters in both galaxies, one of the brightest of which is a starburst region in the lower right, on the end of the outer arm of NGC 2207. Much of this activity has been stimulated by IC 2163's first pass in this merger which is taking place about 114 million light-years away. As a result these galaxies have provided seven supernovae since 1975, five of which have been recorded this century.

  Naturally the HST and JWST images have been combined to provide a highly detailed view of the scene. I particularly enjoyed the "slider" that provides a much better comparison of the action.

  James Whinfrey - Website Administrator.

• January 2025 - Picture of the Month

  Spiral Galaxy IC 342 in Camelopardalis

  

  I thought that it was about time I featured a galaxy, and as luck would have it Capella Observatory have just captured this image of the spectacular IC 342.

  I'm not going to say much about this galaxy because Owen Brazell's already featured it as his Galaxy of the Month way back in September 2012, so you should check out that article.

  As Owen mentions, this galaxy is highly obscured by the gas and dust in our own Milky Way, and in his article he linked to an infrared image of IC 342 taken by WISE pondering how spectacular it might look if where not obscured. In 2012 we didn't have ESA's Euclid near-infrared telescope which captured its own image of IC 342 back in 2023. A great improvement on WISE showing many fainter and bluer star that are the key to studying star formation.

  However this amateur image shows a great deal of structural detail. For example many of the larger star clusters in IC 342 that Euclid observed can clearly be seen here too, especially on Capella's larger version. What I find noticeable in examining the two images is perhaps unsurprising: Euclid shows the spiral arm structure more clearly, but the Capella image makes those dust lanes visible. That's the value of examining objects in multiple wavelengths of light I suppose.

  No doubt that IC 342 is more of an imaging target, perhaps try for those globular clusters, but it is accessible to the visual observer that likes a challenge.

  James Whinfrey - Website Administrator.