Object of the Week - October 20th, 2019 Arp 223

[obrazell]

Arp 223
NGC 7585

Galaxy

Aquarius

R.A.: 23h18m01.2s
Dec.: -04°39'01" (2000)
Magnitude: 12.40 B
Size: 2.6'x 2.0'

In some ways I am surprised this object has not made it to the OOTW already given the focus on interacting galaxies.
This nice pair of galaxies NGC 7585 and 7576 in Aquarius was first discovered by William Herschel. He found NGC 7585
in September 1784 and NGC 7576 a year later in October 1785. The Arp designation only applies to NGC 7585 where
he included it in his class of galaxies with amorphous spiral arms. The galaxy is classified as a lenticular but deep images
suggest to me that it shows shells of material suggestive of a collision with another galaxy, although there is no obvious
candidate for this so must have been a long time ago and the colliding galaxy must been completely absorbed. NGC 7585
is classified as S0-a. NGC 7576 is also interesting is it appears to be a ring galaxy although the pair are not suggested to
have interacted despite lying at a similar distance of 151 million light years as there are no tidal features associated with
either galaxy. NGC 7576 is also classified as a lenticular but with a ring (SA0 +r). Using the near Infra-Red NIC camera on
Hubble appears to a show a strong bar in NGC 7585. For those looking for something more challenging there is the faint
galaxy NGC 7592 a short distance away, although this is also a William Herschel discovery in the same sweep he found
NGC 7585 so it cannot be that faint. There is also a quasar listed as 2315-049, also known as VCV 2001 or NGC 7585 UB1
with a redshift of 1.4, listed on Megastar about 1.4’ SE of the NGC 7585. It has a listed magnitude of18.7 but maybe fainter.
This may be a target for some of the larger scopes on this forum. None of these objects is exciting enough to make any of
the AL’s Herschel 400 lists.

arp223.jpg


And as always,

give it a go and let us know!

[lamperti]

Back in 1992, with a 13" both were seen as a small even glow.

[wvreeven]

My notes with my 20" on September 19, 2015:

NGC 7585: At 320x is see a large, round spot with a bright stellar nucleus. The edge of the galaxy appears to be ring shaped. But the ring disappears at 545x.
NGC 7576: At 320x and 545x I see a fairly small, compact, bright patch of light without much further structure. I get the hint of a dark spot but I am not sure about it.
NGC 7592: At 320x I see a small oval smudge without any further details.

[Steve Gottlieb]

NGC 7592 is actually an interacting contact pair with tidal plumes! It's also catalogued as VV 731, in Vorontsov-Velyaminov's category of "coalescent pairs". The western galaxy has a Seyfert nucleus and the separation is only 13" (measured on ALADIN) from the eastern nucleus. NED actually lists NGC 7592 as a triple system, but the blue southern component is probably a large HII clump in NGC 7592E.

Here are my notes from 5 years back in my 24" at 375x --

The highest surface brightness component is the core of the eastern galaxy (NGC 7592B = 7592E), with most of the glow extending southwest (NGC 7592C = 7592S), creating an asymmetric appearance. The nucleus of the western galaxy (NGC 7592A =7592W) appeared faint and extremely small, perhaps 5" diameter. The arm or wing to its north was not seen with confidence.

NGC 7592.jpg

[Uwe Glahn]

Found two entries to the objects.

NGC 7585
27", 293x-419x, Seeing II-III, NELM 7m0+: very bright, 5:4 elongated, outer halo without any structure

NGC 7592
27", 419x-586x, Seeing II, NELM 7m0+: several knots with different sizes and brightness, N arm easy visible as an arc, extensions to the S fainter and only suspected
NGC7592.jpg

[Ivan Maly]

I have seen all three before. Here is a new sketch of NGC 7592. 20", 150-570x, SQM 21.1 (strong diffuse aurora), seeing 2-4 arcsec.

NGC 7592 2019-10-23 Nup 400w.jpg

[Clear Skies]

NGC7585 - Arp 223

10 September 2015, 1:16, southern France, SQM 21.19, 14" SCT @ 168x/29'
A round glow with a bright nucleus that is visible without AV but is less bright than the nucleus of NGC7576. Using AV the galaxy is slightly oval shaped, subtly elongated WNW to ESE. Gradually brighter in the middle.
To the NNW is a notable meandering Y-shape of mag. 9 and fainter stars with the "V" in the Y-shape on the NNW side.
Almost 1/2 FoV to the SW is the smaller and fainter galaxy NGC7576. Just over 1/2 FoV to the NNE is the galaxy NGC7592.

14 October 2007, the Netherlands, 8" SCT @ 113x/34'
A faint patch, slightly elongated ENE to WSW, the nucleus is very faintly discernible. Close to the north is a mag. 11 star, 1/4 FoV to the NNW is a white mag. 8 star (SAO146621).

1.jpg

2.jpg

3.jpg

NGC7576

10 September 2015, 1:16, southern France, SQM 21.19, 14" SCT @ 168x/29'
Quite bright, slightly elongated north to south, round without AV. Gradually brighter in the middle with AV. The bright nucleus is clearly visible without AV.
Almost 1/2 FoV to the NE is the larger and brighter galaxy NGC7585 (Arp 223).


NGC7592

10 September 2015, 1:16, southern France, SQM 21.19, 14" SCT @ 168x/29'
Individual galaxies can not be discerned: a round glow, gradually brighter in the middle with a bright nucleus that is suspected to be in the eastern galaxy (the nucleus is east of the center, no nucleus is visible west of the center).
Just over 1/2 FoV to the SSW is the galaxy NGC7585 (Arp 223).