Picture of the Month for 2022

• December 2022 - Picture of the Month

  Hubble’s Variable Nebula (NGC 2261) in Monoceros

  

  I've chosen an object that will be much more familiar to most of you than last month's. Many of you will have observed NGC 2261 both visually and with a camera.

  R Monocerotis is a massive Herbig Ae/Be star with a T Tauri type companion. It has recently formed from the dust and gas onto which this nebula is projected, and probably possesses a circumstellar disc. It is also the source of the light that's reflect in our direction, resulting in this nebula which is about a light-year across at a distance of 2,500 light-years.

  Considering the pair of variable stars at it's core, it's perhaps unsurprising that the form of the nebula is also is highly variable. The best explanation of this behaviour is that the form of the reflection nebula is determined by the passage of dense clouds of dust, and possibly the circumstellar disc, as they interfere with the light as it is cast onto the distant backdrop of dust. If true, the morphological changes in the nebular tell us something about the conditions near R Monocerotis itself: not easy data to come by for young stellar objects like these. This is an object that will certainly reward periodic observation.

  This image from Capella Observatory is an great close-up of the beautiful patterns of shadow and light that R Monocerotis throws onto the clouds of dust and gas that surround it. It's a snapshot in time, so don't expect it to look like this when you image it.

  James Whinfrey - Website Administrator.

• November 2022 - Picture of the Month

  Messier 37 and IPHASX J055226.2+323724 in Auriga

  

  This month's choice of image was brought about by Owen Brazell: he posted it recently on our mailing list. Peter Goodhew spoke at our Annual Meeting in 2022, he's part of a team doing some amazing pro-am astronomy, and this result is part of that.

  The name of this recently discovered planetary nebula doesn't trip off the tongue, IPHASX J055226.2+323724, but the open cluster in this image must be familiar to all amateur astronomers. I've no idea how often I've observed Messier 37, with binoculars and telescopes of varying size, and never suspected that this huge object was hiding there.

  IPHASX J055226.2+323724 is about 70,000 years old, and that's a long time to become sparse and faint. Peter Goodhew and Sven Eklund have combined nearly 84.5 hours of imaging time to make it visible in colour: this is not a visual object.

  The most exciting aspect of this discovery is that the planetary nebula is associated with Messier 37, so this is the result of the death of one of the cluster's stars, and this is apparently only the 3rd example of such an association in the catalogue. It's also this association that makes this image so fascinating for me.

  James Whinfrey - Website Administrator.

• October 2022 - Picture of the Month

  The Andromeda Galaxy (Messier 31)

  

  It's fair to say that this month's choice is not at the 'obscure' end of objects for Picture of the Month. Messier 31 has probably been observed by most amateur astronomers, and imaged by many.

  Our neighbour covers a patch of night sky about 3° in length and 1° wide, and at a distance of about 2¼ million light-years, it's about 150,000 light-years in diameter. It also has another two familiar galaxies literally in tow, M32 and M110, and that bright star cloud, NGC 206, to observe too. Binoculars are a good may to observe it, and astrophotographers might struggle to capture the whole field.

  It's my choice because some sights are taken for granted.

  I think that Patrick's image captures this particular sight beautifully: pulling out far more detail than the eye, but without making those dust clouds too harsh, or blowing out the galaxy cores. Patrick has much more detail about this image, his methods, and his journey to this version–it's his third attempt–on his blog. I enjoyed reading it.

  James Whinfrey - Website Administrator.

• September 2022 - Picture of the Month

  Stephan’s Quintet (Arp 319) in Pegasus

  

  I thought it was about time a galaxy had Picture of the Month, and when I noticed that Stephan's Quintet crosses the northern meridian at a sensible hour in September, and that I'd never featured it before, it was time to choose this image of six galaxies by Adam Block.

  A quintet suggests five, but NGC 7320C on the right isn't a member of the group, being closer to us at about 35 million light-years. However several hundred million years ago it certainly was, as is plowed through group colliding with NGC 7319 in the process.

  Of course, even if it seems central, NGC 7320 isn't a member either. It has to be admitted that it looks very different from the rest of the group with all that blue star formation and its clumpy HII regions. It's also much closer, like NGC 7230C, and is visually the brightest galaxy here at 13.2V magnitude.

  The other four galaxies in this image form a physical group in the process of coalescing at around 300 million light-years from us. This is most obvious in NGC 7318, both the A and B halves of it, but NGC 7319 also shows significant disturbance and tidal tails extending towards NGC 7320C. Only NGC 7317 seems quiet, down there in the bottom right.

  This galaxy group has been well imaged with professional scopes, including the Hubble and recently the Webb Space Telescopes, and it is a but popular visual target, but I was surprised how few amateur images I could find.

  James Whinfrey - Website Administrator.

• August 2022 - Picture of the Month

  Weinberger 1-10 in Cygnus

  

  I've chosen a planetary nebula (PN) that, despite rising high in the northern night sky this month, definitely isn't one for the visual observers. It's that small bluish circular object near the centre of the image: Weinberger 1-10.

  Weinberger 1-10 was discovered during a search of the Palomar Observatory Sky Survey (POSS) photographic plates. It was one of twelve that would be published in New planetary nebulae of low surface brightness (Astronomy and Astrophysics, Suppl. Ser., Vol. 30, p. 343 - 348) by Ronald Weinberger in 1977. He had good eyes as a young man of 29. I can't see much on the Digitised Sky Survey (DSS) images, and this was one of the most obvious PNs that he spotted.

  Weinberger 1-10 is a reasonably large object at 190 arc-seconds in diameter, but is indeed low surface brightness. As you can see in Jens' image, this PN is almost hidden by the surrounding bright nebula (LBN 381) which is itself not particularly bright. The PN's central star is 18.7 magnitude.

  And yet, this image shows detail around the edges of that faint bubble. I chose this image of Weinberger 1-10, and there aren't many, because the composition conveys the tenuousness of this structure, nestled on the edge of that Hα emission in the dense star fields of Cygnus. A challenge indeed.

  James Whinfrey - Website Administrator.

• July 2022 - Picture of the Month

  The Great Peacock Globular (NGC 6752) in Pavo

  

  We're still down in the southern hemisphere, but we've moved about 20 degrees north this month to find another fine globular cluster. In fact it's the fourth brightest in the sky, so I couldn't overlook NGC 6752 since it's peak observing season for this object, and Mariusz happens to have recently captured this wonderful image.

  NGC 6752 is not only brighter, by nearly five magnitudes, than IC 4499 from last month but it also displays a condensed core, being classified as Shapley–Sawyer VI. It's also much closer to us at 13,000 light-years (4 kpc). Hubble has also imaged this globular, whilst surveying white dwarves, and discovered a galaxy hidden behind it.

  As well as a spectacular imaging target, NGC 6752 is unlikely to pose problems for visual observers either: it's apparently a naked eye object and I expect it looks fabulous in binoculars or a telescope.

  Unfortunately for me, southern observers have a virtual monopoly on those four bright globulars: from the UK Messier 22 scrapes the horizon this month in Sagittarius, and the others are only visible from much further south. I hope they appreciate them 😉

  James Whinfrey - Website Administrator.

• June 2022 - Picture of the Month

  Globular Cluster IC 4499 in Apus

  

  This month I wanted to head south because of the short nights in the northern hemisphere. I ended up as far south as any globular cluster in our galaxy would permit, with this image by Steve Crouch of IC 4499 in southern Apus.

  This is a halo globular that lies about 65,000 light-years (20 kpc) from us, although high reddening in its direction make this measurement tricky. It's sparse for one of its kind, hence the Shapley–Sawyer classification of X–XI, and has a magnitude of 10.1V. Consequently Annals of the Deep Sky Vol. 1 claims that it's an easy object with a 12in telescope, although unimpressive due to the lack of a condensed core.

  IC 4499 was thought to be unusual: the metallicity of an old globular cluster, but a surprisingly young age derived from a photometry study of its population of RR Lyrae stars. This caused speculation about the origins of this object, was it a recent capture?

  However new photometric observations with the Hubble have demonstrated that IC 4499 has a much more conventional age for a galactic cluster of around 12 billion years. Hubble also produced another spectacular image of IC 4499 in the process.

  James Whinfrey - Website Administrator.

• Messier 102 (NGC 5866) in Draco

  May 2022 - Picture of the Month

  

  When I saw this Hubble Space Telescope (HST) image again, and given that Messier 102 (NGC 5866 if you prefer) is high in our May sky, I just had to feature this galaxy. But try as I might to find an amateur image to do it justice I kept coming up blank. So I'll admit it, I cheated and use the venerable HST image you see above.

  Obviously what makes this galaxy so spectacular is that filigree dust lane that, because we're viewing it edge-on, is superimposed on its bright disk of blue stars and its core. The HST image shows it off beautifully, but it's even more impressive in the full resolution images. I love the contrasting clean glow from the outer halo too.

  Given that Messier 102 is classed as a lenticular galaxy a dust disk like this is unusual. On the other hand it might be a misclassified spiral that we're looking at, and the mystery goes away. It's hard to be certain from this angle. There are also signs that the dust disk has been disturbed, perhaps as the result of a merger?

  From the ground

  Clearly even elderly space telescopes have an edge when it comes to resolution, so in addition to the featured image from orbit I wanted to show you an image taken with professional equipment from the Kitt Peak observatory back in 1995. Some of that detail in the dust lane is still visible.

  

  But equipment and techniques have moved on, and in 2019 I received this image from David Davies, duly adding M102 to our Observations section. I've included a cropped of that image that I've rotated to the same orientation of the one above.

  

  Pretty close I think you'll agree, better in many regards. And not take at altitude, but from near sea-level with murky jetstream washed skies on some of our shortest nights. If you read David's notes you also discover that he was using a 203mm aperture scope and not the 900mm of Kitt Peak.

  So why is it so hard to find other good amateur images of this impressive edge-on galaxy when other Messier objects are so frequently imaged I wonder? Now is a good time to put that right 😁

  James Whinfrey - Website Administrator.

• April 2022 - Picture of the Month

  Longmore-Tritton 5 (LoTr 5) in Coma Berenices

  

  A planetary nebula that, unlike last month's, was was discovered photographically on the plates of the UK Schmidt Telescope by A. J. Longmore and S. B. Tritton, hence the designation LoTr 5.

  As you might expect from a photographic discovery, this is a large (~500 arc-seconds in diameter) and faint planetary nebula. It's about 1650 light-years from us and at that distance its angular diameter converts to 3.6 light-years.

  No problem spotting the central star in Bernhard's image. It's that nice bright yellow one (HD 112313 or IN Com) at magnitude 8.8V. IN Com a rapidly rotating variable of interest in its own right, but a yellow G-type star wouldn't normally ionise a nebula like this one. As it turns out, this is a binary star with an O-type white dwarf secondary that lights up the nebula in O-III.

  LoTr 5 has been found to be a bipolar planetary nebula, a structure which is common in nebulae with a central binary star. The axis of the bipolar 'hour-glass' shape is angled at about 17° here, and may provide a view of the edge of the far lobe on the right of this image.

  So this month we have a terrific image of a planetary nebula, a binary star, and a variable star as well.

  James Whinfrey - Website Administrator.

• March 2022 - Picture of the Month

  The Southern Owl Nebula in Hydra

  

  As Patrick is concentrating on The Owl Nebula (M97) in Ursa Major is month, I thought that I'd visit its lesser known cousin in Hydra which you can see in this wonderful image by Steve Crouch.

  ESO 378-1 (PN K1-22) was spectacularly imaged by ESO's Very Large Telescope (VLT) in 2015, but the Southern Owl Nebula gained its informal name back in 1999 due to its similarity to M97 in the eyepiece. The NASA Astronomy Picture of the Day featured a side-by-side comparison of M97 and ESO 378-1 by Don Goldman in 2010.

  There is a strong family resemblance: both are planetary nebulae about 2,000 light-years away, they're about the same physical size, and have very similar morphology. However ESO 378-1 is a much fainter object with a visual magnitude of 17.4 as opposed to M97's 9.9.

  So not a visual target then? It seems that it has been visual observed in telescopes as small as 8-inches of aperture, though I suspect excellent skies are required for that. ESO 378-1 does appear on the Astronomical League Planetary Nebula Observing Program southern list though, which suggests this size telescope as a minimum. Unfortunately for northern observers, the Southern Owl, at below -34° of declination, barely clears the horizon.

  James Whinfrey - Website Administrator.

• Dwarf Galaxy Holmberg II in Ursa Major

  February 2022 - Picture of the Month

  

  Back to galaxies for February and a member of the M81 group in Ursa Major that lies only about 10 million light-years from us. Holmberg II is a dwarf irregular galaxy, and I don't think it's too hard to see why, on the edge of its galaxy group safely away from the gravitational effects of the larger members. All the same, it is forming plenty of young massive blue stars which can be seen in David's image as the blue regions, giving the galaxy a knotty appearance.

  This galaxy's low mass and quiet neighbourhood allow structures created by generations of stars to survive for a relative long time, giving the Hubble Space Telecope (HST) a chance to image them. This it duly did, in a spread of wavelengths from the visible to near-infrared, revealing huge bubbles in its interstellar medium created by a succcession of solar winds of massive stars and supernovae. Sequential star formation has inflated these bubbles to 300–5,500 light-years in diameter.

  Holmberg II is also home to an ultraluminous X-ray source, the location of which David has indicated in a crop of this image on his website. The source itself is at the intersection of three gas bubbles. This may be an intermediate mass black hole that's drawing on the abundant gas around it.

  There are some reports of observing Holmberg II visually, but it would need a large aperture telescope and dark sky.

  James Whinfrey - Website Administrator.

• The Jellyfish Nebula (IC 443) in Gemini

  January 2022 - Picture of the Month

  

  I don't have many supernova remnants (SNR) in Picture of the Month, the last was over three years ago, and it's a shame because they're spectacular objects. But I have a great example in the bottom-right of Sara's image: IC 443, also known as the Jellyfish Nebula because of those billowing folds.

  IC 443 is about 5,000 light-years from us and is between 3,000 and 30,000 years old, spawned in a Type II supernova that also created pulsar CXOU J061705.3+222127. The nebula's distinctive shape is the result of interaction with an interstellar molecular cloud, whose variable density dictates the local structure and composition of the SNR. It's become something of a case study for shock chemistry in molecular clouds.

  Positioned between μ and η Geminorum (at the extreme left and right respectively) it is easy to find the right location, but not so easy to see despite being 50 arc-minutes in diameter.

  The section of IC 443 to the North-East is the brightest, and visual observation is possible, with an O-III or UHC filter being helpful. I've seen reports of success with telescopes from 8 inches and up, but to see much, bigger is definitely better. However success depends primarily on the quality of the sky: this is not a visual target for light polluted skies.

  It is a splendid imaging target, though long exposures are necessary, and probably a good candidate for Electronically-Assisted Astronomy (EAA). This is especially true when combined with the glowing reflection nebula in the top-left corner of this image: IC 444 and its associated dark nebulae.

  James Whinfrey - Website Administrator.