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Martin Meredith

Vorontsov-Velyaminov interacting galaxies

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Posted (edited)

Here are three highlights from a tour of the VV galaxies in Delphinus and Aquila (7 in Del and 2 in Aql). Conditions were not good.

VV 102 (UGC 11672) in Del. This is a pair of spirals that are coalescing (given PC designation), about 460 million lyrs away.

329235258_VV10210Aug20_10_49_50.jpg.fce12a568fdfe33206220140d0d0f244.jpg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VV 773 (UGC 11564) in Del. This pair have a bridge between them and are about 240 million lyrs away. Sort of got a hint of the bridge.

2007770410_VV77310Aug20_10_51_01.jpg.75213daa643f4c99de0dd7d73fb77669.jpg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VV 621 (NGC 6926) in Aql. It has the designation of N, meaning 3 members interacting. But is it just one large spiral that is being disturbed by gravitational interactions with ??? See link: https://www.webbdeepsky.com/galaxies/object?object=NGC6926

 

1409207669_VV62110Aug20_10_52_33.jpg.a0d8fb8627b106d49dc1523c949063c7.jpg

Edited by Mike JW
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Posted (edited)

Hi folks,

Now we all know Equuleus is a waste of space visually!!!! but there some gems to take a look at using the EEVA technique.

VV 476  (UGC 11680) - a mag 15 galaxy with a satellite companion at the end of an arm. Conditions were poor last night (light haze, high humidity but steady skies) but nice to be out there in shorts. It was daft to go for this target but you never know what might be seen. Is the galaxy at the end of the lower arm a line of sight ?  red shift suggests not. So quite likely the satellite is interacting with the main galaxy.

1026175351_VV47612Aug20_09_06_55.jpg.b6b3251613c7793b91eaadbef8d828b8.jpg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VV 508 - also a mag 15 but this time classified as 'Ch'  - meaning a chain.  First glance it was tempting to think it was a chain of 3 galaxies and maybe one offset, making a total of 4 but then maybe two galaxies and two stars. So off we go to Aladin/NED data. It really is 3 galaxies in a row and the offset fuzz is a star. Close inspection of Aladin indicates various other very faint galaxies (mag 18) which coincide with fuzz spots on this shot (could be be noise  that happens to be in the right place). There are various brighter galaxies in the shot -see  ST4 screen shot to help locate them.

Mike

1942037912_VV50812Aug20_09_20_31.jpg.8ca597571fb2e02d5458069ed3f9c47f.jpgimage.png.29a0a88c943d150bd513f09ff4319ad0.png

 

 

 

 

Edited by Mike JW
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Posted (edited)

Fascinating shot of VV 508. It shows that the VV catalogue is full of surprises. So is the offset star in the ST4 shot?

Martin

[Edit: dug into my archives and found this shot of VV 508 -- I thought the configuration looked familiar! I see my stars are not as round as they ought to be... ]

661969197_VV50812Aug20_20_56_23.thumb.png.b4b3a96b79bf9de30835b93189153e8f.png

Edited by Martin Meredith
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Posted (edited)

And I obviously had the same idea as I also have this one of VV 476, stretched relentlessly with about 6m of exposure in 10s subs. The companion is very faint.

234363937_Screenshot2020-08-12at21_02_40.thumb.png.3367f13026e20519dff3d202461c3e77.png

 

 

 

`

Edited by Martin Meredith
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Hi Martin,

Great to able to compare your results as well, which I think are better as far as galaxy details go. Conditions were rubbish last night - so much humidity. VV 476 is definitely better than mine. The central part of the galaxy has a ring like feel to it - fascinating.

Mike

 

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Tried again last night with VV 476. No real improvement in the detail observed but I enjoyed the revisit. I need to wait until we have a colder, transparent night. Mike

799311507_VV47613Aug20_09_12_56.jpg.b2a18c5b1310feeb0e6b1eaf4505a669.jpg

 

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August 18th - transparent skies and warm (too warm for an uncooled camera?). Two VV galaxies in Capricorn.

It is easy to always post shots of interesting objects, so here are two boring ones! but pleased to continue my VV galaxy journey.

VV1889 - pair of spirals in contact and disrupted (PKdf ), mag 15.5                   VV 1907 A spiral and an elliptical galaxy that have coalesced (PC), mag 14.5. NGC 7030

1479523714_VV188919Aug20_08_04_05.jpg.da740e553f56f307adbb2ad742fbce7d.jpg512387513_VV190719Aug20_08_05_01.jpg.148e6d5219864e9f08d53e42b38568df.jpg

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Hi Mike

Good to see some galaxies in Capricorn, not a constellation I have visited much myself. Glad you had transparent skies -- I was out last night with the opposite... but since I was mainly looking at open clusters it wasn't so bad. I will post a few later.

Regarding cooling, I may be missing a whole world of high fidelity captures but I have never found its absence a big problem for this style of observing (tonight it is predicted to be 27 C at 9pm so maybe I will eat my words). The key seems to me to be automatic hot pixel removal rather than darks. Any failures in that department are easily noticeable when using colour! Here's an example from part of M16 last night with and without hot pixel removal: 

900651956_Screenshot2020-08-19at13_23_39.png.702ebd95ec4c5859d564cae3b7186edd.png

I don't see many/any hot pixels in your captures so I imagine it is working correctly. I do notice that at this time of year the number of bad pixels reported is somewhat higher (a quick check showed about 70 in a January capture versus about 130 last night).

Martin

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Hi Martin, thanks for the technical info. I always have the hot pixel removed box ticked in Jocular. The buzz last night was using the EEVA technique to get a view of these low down targets - no way could I have reached them with a big Dob.

Mike

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BTW hot pixel removal in Jocular is based on co-occurence in multiple subs (three at present, but configurable). So if you do see the occasional hot pixel it is quite possibly a cosmic ray... which I think we can get away with as astrophysically-interesting event rather than an artefact. (Still annoying when using colour filters though!)

Martin

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In Mike's spirit of let's look at because we can... here's a first foray into Microscopium for me. This pair, VV 1895, transits at a dizzying 18 degrees (I observed them at about 16 degrees). South for me is right into the village streetlamps and general murk (leading to diffuse star shapes) so is never ideal for capturing low-lying objects but even so they are recognisable as spirals. The northern member is IC 5007, a mag 13.1 type Scd galaxy, while the lower galaxy is IC 5039, mag 13.2 type Sbc.  There is a mag 17.4 galaxy at the N tip of IC 5039 that is just about visible. They are also listed in the Arp Madore catalogue with the description 'wide pair of bright spirals and companions' (the latter referring to a scattering of mag 16-18 galaxies in the vicinity).

1643826776_VV189520Aug20_22_22_13.png.2e20e3a2e0eba359dc7ed5e404960e57.png

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Hi Martin, this VV is one I shall never see. VizieR classifies it as M.  Mike 

image.png.10bccc595f0bb2ad8eb7f2af1237d2ae.png

 

 

image.png

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5/09/20. As well as Arp 46 (VV 314) I fancied a VV galaxy so I went for VV 400, (NGC 7698)  It is a lovely elliptical but is classed as MMM = satellite lies on the bridge connecting the components. That classification defeats me - I see no companion or a bridge.

However to compensate for this lack of companions note the galaxies at top right - several LEDA galaxies. Note also a small diamond shape of four fuzz spots approx 12 o clock from 7698 - another group of galaxies?

Mike

1747398679_VV40006Sep20_15_57_02.jpg.3a32ffed8f283499c297ffda196f33d0.jpg

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This is a group I came across by accident last night in Lacerta. There are two VVs here.

710784391_NGC724210Sep20_14_18_34.thumb.png.d8d5695de3b95ee333b012299c18696e.png

VV 1935 is classified as PC = 'pair of coalescence'. It is hard to see which are the galaxies here due to the field stars, but I see two small oval candidates (aligned 10 o'clock and 2 o'clock), each seeming to emerge from behind an accompanying star...

VV 1936, also classified as NGC 7240, is M-type, meaning M51-type with one satellite. The M51 galaxy is quite clear but what isn't obvious is whether the satellite is the block just above it, or the slight nodule on what looks like a very thin spiral arm at the S of the galaxy.

The other galaxy in this shot is the mag 15.4 SBb-type IC 1441 (it looks elliptical here).

I spent quite some time on this pair, not just to look for the details, but because they are part of a very interesting wider field (which also helps put the apparent size of the VVs into content):

 

1337683253_NGC724210Sep20_14_09_39.thumb.png.8aa4c5f672678a6763f496c0ff383891.png

This is a part of the sky (near the border with Cygnus and Pegasus) where the stars are still quite dense which I think adds to the interest. NGC 2742 is the bright galaxy just above the centre. This is a mag 14.0 elliptical. It is more interesting than many ellipticals that I've observed with a very extensive halo. There are some lovely edge-on galaxies here too (hence the framing). The one to the right is UGC 11963, a mag 14.9 S0-a type with a dense core and flying saucer shape. Looking somewhat similar, at 8 o'clock is PGC 68466, a mag 15.6 Sab-type. 

I'm not sure if this group has a designation but does seem to be regarded as a group. The earliest reference I can find to it is a 1920 paper by Pease http://articles.adsabs.harvard.edu/pdf/1920ApJ....51..276P which talks about 20 members. Distance estimate are in the range 250-320 MLyrs so it is possible that some of these are physically-linked.

cheers

Martin

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Hi Martin,

I looked at these in August but never got round to reading up about them. Wonderful area to explore and thanks for the info.

Mike

732041571_VV1935193610Sep20_16_06_40.jpg.17e371e98947a4b118991fad8ad60e29.jpg

1282509506_VV1935193610Sep20_16_07_08.jpg.3870974582dda437c27d8b0a7af37b04.jpg

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Here's a very fine and maybe under-appreciated group from the VV catalogue: VV84.

This was a chance encounter from last night. I took one look at this and started searching for alternative designations. Surely this must also be an Arp? a Hickson?  VV84  strongly resembles Hickson 79 -- Seyfert's Sextet (or is it Septet?). But no.

Here's a wide field (well, 0.4 degrees!) shot which shows just how compact this group is.

1754082230_VV8411Sep20_11_11_32.png.56303f45843ae899fda42a29b4c26f5c.png

And here is a closeup of the group, oriented N

 

1251888972_VV8411Sep20_10_51_47.thumb.png.8ea05d1fa222603ae9e5fdb30aa01014.png

 

 

[EDIT: Looks like I mislabelled a galaxy here: PGC 70012 is actually NGC 7433 (mag 14.0 Sbc). It appears PGC 70112 is the same galaxy, but it is odd that it has different listed magnitude]

I couldn't find much information online. One of the few references http://articles.adsabs.harvard.edu/pdf/1989ApJ...345..176L regards VV84 as a triple system but there are more than 3 galaxies involved to my eyes, with 6 having reported distances around 350 MLys. I read that the main elliptical, NGC 7436, contains a supermassive black hole, and one report suggests that it contains little or no dark matter https://arxiv.org/pdf/0906.4448.pdf. The pair NGC 7435/7436a are partially overlapping and have been used to study light absorption of background by foreground galaxies https://arxiv.org/pdf/astro-ph/0007361.pdf

There are other interesting groups in the wider shot, including the 3 edge-ons (one bright, 2 faint) to the lower right. 

Its an intriguing side-question to consider why VV 84 didn't make it into the Hickson catalogue, or given an Arp designation. After all, some Hickson groups are also Arps and VVs, some VVs are Arps, etc. Hickson's paper is well worth a read was it goes a little into the chronology of compact group discovery and of course lays out his selection criteria.  http://articles.adsabs.harvard.edu/pdf/1982ApJ...255..382H In this case it might be that the bright edge on to the lower right (UGC 12274) is regarded as part of the VV84 group -- it has a similar distance estimate -- and maybe then the group as a whole fails the compactness criterion. Opinions?

cheers

Martin

Edited by Martin Meredith
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Hi Martin, What a great find this one is. It is on my list of Pegasus VVs but as I am working through them logically using RA co-ordinates it is way down my list - 23 to go before I reach this one. I think I might do a quick detour on the next occasion.

I would agree with your thoughts re why it is not a Hickson (but I would have to point out my lack of knowledge/understanding.....)

Vizie R classifies it as NNNP = triple with a tight pair. I assume the VV 84 is actually the row 3 horizontal crosses below and to the left of NGC 7433, and not 7433 or/and 7435

Below is the Aladin screen shot - left cross has redshift of 0.024600, middle cross has redshift of 0.024610 and the right hand cross has redshift of 0.025347.

NGC 7433 has redshift of 0.025311. I have tried using a converter to find out the distances.

Left cross = 337mlyrs, middle cross = 340mlyrs, (therefore close to each other = NGC 7436). NGC 7436A - right hand cross = 350 mlyrs.

 NGC 7433 = 349 mlyrs and thus is close to the right hand cross (NGC 7436A)

The redshift distance  of 0.027272 for NGC 7435 is 376 mlyrs - so not an immediate  neighbour.

As to UGC 12274 (not on my aladin image) I came across a distance of aprrox 300 mlyrs so somewhat nearer to us.

Very interesting to muse on this image - thanks Martin for posting.

Mike

2088798590_AladinVV84.png.367a5a434000af9e4a41ad9f37419dea.png
 

 

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Thanks for this info Mike. Aladin (and Vizier and Simbad) really are wonderful resources and we are so lucky to have access to all this literature. Good luck with your VV trawl. It is definitely a good approach in terms of spotting treasures like this. I am more haphazard but if something looks interesting on the charts I sometimes strike lucky. I never look at Aladin first though -- that really would be cheating!

Tonight is another clear one -- so tiring 🙂 I still have another 20 or so Berkeley OCs to observe but this means dragging the scope out to the back of the house and it is a bit of a wind tunnel on a breezy day like today, so it is likely to be more Pegasus for me tonight...

Martin 

 

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Here is my result from the 15/ultrastar set up. Mike

930729608_VV8411Sep20_21_46_56.jpg.1bab9aab862d702707ea16ca726a20fb.jpg

1547113939_VV8411Sep20_21_46_28.jpg.3ed47ea3c7d88c8ad0bbc180e30e3e48.jpg

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14/09/20

It is always a temptation to post the obvious 'wow' views we get via EEVA. So here is a 'boring' view but actually on close inspection it holds interest.

VV 1958 in Pegasus - UGC 12280. Mag 15.5 pair of galaxies in contact (PK), 500 million lyrs away, both spirals.

The close up shows they are angled to each other as they interact and there is a hint of disruption - see Aladin view.

Just after I started the subs for this target my neighbours came out and I showed them the planets and totally forgot I was running the camera, hence the 11 mins of subs (actually it was over 13 minutes but I dropped some of the unsteady subs). This length of time is hardly 'live' in the EEVA sense but the result is of interest.

Mike

 

1281584632_VV195815Sep20_09_07_53.jpg.bfd55f62867f5c00fc1648941d27cd78.jpg113611247_VV195815Sep20_09_10_11.jpg.6b7d01ba92221b3c211b722140d25b82.jpg

image.png.114fee19868221166044b18e1e85c508.png

 

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I think they're all interesting especially with a bit of a back-story.

I have similar thoughts sometimes about the observation length, but on the other hand I can easily be spending up to 20 minutes on a particularly faint or compelling object so if that ends up with a smoother image, all the better. I occasionally go longer still. Very faint but rich Abell-Corwin-Olowin galaxy clusters are amongst my favourites as I love seeing them appear like fireflies, growing in number as stacking proceeds; and this can take some minutes before more than a few are visible. I think the longest I've spent (so far) has been on a faint quasar that (at the time) had an estimated redshift that put its light in the first billion years of the universe. I've since found that the redshift was overestimated.... so that is a personal challenge I still have. And the other occasion was (at the other distance extreme) trying to spot a very cool star (a brown dwarf called DENIS something :-). Longer observations are sometimes necessary and have their place as the only practical way to see certain things with an 8" piece of glass.

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