June 2026 - Picture of the Month
Cat’s Paw Nebula (NGC 6334) in Scorpius
This is very small piece of bright nebula NGC 6334, also known as the Cat's Paw Nebula. The whole object is approximately 30 arc-minutes in extent and 4,000–5,800 light-years away from us, nestled amongst the abundant clouds of Scorpius and the Carina-Sagittarius arm of the Milky Way.
This nebula has featured in Picture of the Month before as part of a fabulous and very widefield mosaic view of the centre of the Milky Way by Robert Gendler which really shows the richness of this part of the sky. That was the article for July 2016, nearly ten years ago! In that image there were sections of at least three different constellations; in sharp contrast this James Webb Space Telescope (JWST) image is only about 6 arc-minutes across.
NGC 6334 contains some of the most active sites of massive star formation in our Galaxy, which the whole region appears to be undergoing an accelerated rate, possibly due to a collision of molecular clouds 1.
Of course, given that it's a JWST near-infrared image, we can see features that are normally completely hidden in the dense clouds that fill the region, in particular those massive O-type stars etching bubbles in the surrounding cloud and compressing dense knots of dust and gas where protostars are protected around their edges. You can clearly see the fiery glow of stars forming within the dust in the centre of this image.
At the top of the right side of this image is a bright orange-red flare which is part of NGC 6334-I, the densest star-forming region in the area. However the same location looks like empty space above the most northern part of the Cat's Paw in optical images (celestial north is broadly to the right in this image) such as this fabulous example from 2007 taken with the Mosaic-2 imager on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory.
It was in NGC 6334-I that the Atacama Large Millimeter/submillimeter Array (ALMA) was used to study water vapour jets issuing from a massive protostar in 2018, a fascinating radio-frequency image, and the chemical richness of the environment around these forming stars. ALMA data was also used to investigate star formation in the area around NGC 6334-I, finding that nearby NGC 6334-E contained the most evolved HII region, whilst clusters to the north were less developed 2, thus still heavily shrouded in the molecular cloud.
In fact, outside of optical wavelengths NGC 6334 displays a filamentary structure that can be seen in a wide infrared image from ESO's VISTA in 2010 extending for some 100pc (326 light-years), which doesn't look all that paw-like anymore. NGC 6334-I and E can also be seen in this image as the bright emission region. Our JWST view is aligned with one of these filaments, NGC 6334 M, the very one that was studied with ALMA, which runs between those obvious blue reflection regions broadly from the lower left corner to the top right of this image.
So with all of those links I suppose that this has become Pictures of the Month in a sense, but multi-wavelength observation is the theme of this article.
This object is going to be tricky of more northern visual observers, being less than a couple of degrees above the horizon from most of the UK. However The Night Sky Observer's Guide Volume 4 suggests that it's accessible to very modest telescopes and enhanced with a UHC filter in larger ones.
James Whinfrey - Website Administrator.
References
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Yasuo Fukui, Mikito Kohno, Keiko Yokoyama, Kazufumi Torii, Yusuke Hattori, Hidetoshi Sano, Atsushi Nishimura, Akio Ohama, Hiroaki Yamamoto, Kengo Tachihara,
Molecular clouds in the NGC 6334 and NGC 6357 region: Evidence for a 100pc-scale cloud–cloud collision triggering the Galactic mini-starbursts
, Publications of the Astronomical Society of Japan, Volume 70, Issue SP2, May 2018, S41, https://doi.org/10.1093/pasj/psy017 - Physical properties of the star-forming clusters in NGC 6334 - A study of the continuum dust emission with ALMA, M. Sadaghiani, Á. Sánchez-Monge, P. Schilke, H. B. Liu, S. D. Clarke, Q. Zhang, J. M. Girart, D. Seifried, A. Aghababaei, H. Li, C. Juárez and K. S. Tang, A&A, 635 (2020) A2, DOI: https://doi.org/10.1051/0004-6361/201935699
