NGC 5430, a Wolf-Rayet galaxy

[Menno555]

It's been a while that I've been able to capture but there was an unpredicted very clear night (finally!!)

And again with a more illuster "smaller" target: NGC 5430. I really do like the "underdog" objects over the big(ger) spectacular ones
NGC 5430 sits at around 130 million light years and has a magnitude of 12. At first look I thought it was a pair of interacting galaxies but it turns out to be a barred spiral galaxy.
It also has Wolf-Rayet stars in it, hence the term Wold-Rayet galaxy. These kind of stars are very rare. Not because they are big and very hot (which they are), but because they have no hydrogen. For more info, see https://en.wikipedia.org/wiki/Wolf–Rayet_star

Of course not visible here as individual stars but they are in a blueish "knot".
See the annotation version below (knoop is the Dutch word for knot )

The full 2600x1866px versions can be found here:
RGB: https://i.ibb.co/Xs7HNTh/NGC-5430-RGB.jpg
Annotations negative: https://i.ibb.co/NZLnYds/NGC-5430-annotation.jpg

Menno

NGC 5430_RGBsm.jpg (241.18 KiB) Viewed 4290 times

NGC 5430_annotationsm.jpg (247.41 KiB) Viewed 4290 times

Bortle 6/7
Meade LX200 8" f/10 ACF OTA
Ioptron CEM25EC mount (no guiding)
Baader IR/UV Cut filter
Zwo ASI071MC Pro camera

Captured with SharpCap Pro @ -10 Celsius / White balance R50 B50
35 x 180sec / Gain 90 / Offset 4
Darks + (dark)flats

Stacked with SiriL (m.b.v. SiriLic)
Processed with SiriL and Photoshop

[admin]

Hi Menno,

lovely images and an informative write-up too. It makes you wonder about what happened to create so may Wolf-Rayet stars that they can be clearly seen from such a distance!

cheers,

Robin

[Menno555]

Thanks Robin

I found a NASA/ASP paper from 1982 that suggests that this knot (which also contains a lot of O-stars) is caused by a collision of a irregular dwarf galaxy with the disk and bar of NGC5430. That would also explain the somewhat odd shape of the upper arm (this is my own thought).
It also says that if the WR-stars there are like the ones found in our own galaxy, there could be up to 30,000 WR-stars in that knot.
Which is kind of mind boggling since they only discovered a couple of hundred WR-stars in our own galaxy.

Menno

[timh]

How interesting! I like imaging the WR stars in our own galaxy - or rather the nice OIII- bright nebulae that they tend to slough off and illuminate around themselves. You are good at digging up these little gems of information Menno. thanks Tim

[Menno555]

Thanks Tim!
Because of NGC 5430, I now know about WR-stars
And it's actually not so hard to find information (I think ). If I look for information on lets say M51, I get tons and tons of pages with info. And that makes it hard to search for remarkable things.
But for the (more) unknown objects, there are just a few (or way less) pages and information stands out more.

Menno

[kaymann]

I tried NGC 5430 last night and was no where near as good as your photo - fantastic photo!!

[Menno555]

Thanks Randall!
Don't know how many captures you made or what your staking and processing process. Or the sky quality: this night was very good with very low seeing.

Menno