Object of the Week, December 4, 2016 - NGC 1530, a remarkable barred spiral

NGC 1530 = UGC 3013 = MCG +13-04-004 = CGCG 327-017 = VII Zw 12 = PGC 15018
RA: 04h 23m 26.7s
DEC: +75° 17' 44"
Type: SB(rs)b
Size: 4.6'x2.4'
P.A.: 17°
Mag: V = 11.5, B = 12.2

German astronomer Wilhelm Tempel discovered NGC 1530 in 1876 using an 11-inch Amici refractor, while working at the Arcetri observatory in Italy. This relatively prominent galaxy was discovered fairly late visually as it was missed by both William and John Herschel, who only made a limited number of sweeps in the far northern sky.

Camelopardalis contains several bright, interesting galaxies including the multi-arm spiral NGC 2403, the giant HII-knot dominating NGC 2366, the "Dusty Hand" structure in NGC 2146, the Super-star clusters in NGC 1569 and more. But NGC 1530, a dramatic twin-armed barred spiral, seems to be rarely mentioned in observing guides despite that it has a classic grand-design barred shape. It's not included in Stephen O'Meara's "The Secret Deep" book and it's missing from Jeff Kanipe and Dennis Webb's new "Annals of the Deep Sky", though it is bright enough to be visible in a 5" scope.

The well-defined thin spiral arms of NGC 1530 break away sharply from the ends of the long prominent bar and extend quite a distance north and south. Interesting they have short opposing lengths, curving inward from the tips of the bar as extensions of the main arms. On optical images the bar contains prominent dust lanes that spiral into the nucleus which contains a mini-spiral! Prominent star–forming regions are visible in the arms near the ends of the bar. Studies have shown that gas is funneled inward by the strong bar, contributing to a prominent star–forming nuclear ring and feeding the central supermassive black hole.


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Through my 24", NGC 1530 is fairly prominent, elongated nearly 3:2 N-S, roughly 3.5'x2.2' with a bright core and fainter bar oriented NW-SE. A low contrast, thin spiral arm is attached on the west side of the bar and sweeps north at the edge of the halo. A similar arm or enhancement is visible on the east side extending due south. The "counter" arms extending inwards were not seen. Two mag 15 stars [22" separation] are superimposed on the NE side [1.1' from center] and a mag 12.8 star lies 2.5' N.


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A month ago I had another view of NGC 1530 through Jimi's 48" and was amazed by the symmetric beauty of this galaxy. Here are my notes at 488x --

Bright showpiece barred spiral! A relatively wide, very prominent bar extends WNW-ENE [PA 122°] and is steeply inclined to the orientation of the core. The bright core, centered on the bar, is elongated N-S and contains a very bright round nucleus that increases to the center. Two relatively bright and very distinctive thin spiral arms extend from the ends of the bar. The western arm is brightest in a region near the root, where it attaches to the bar and contains a small knot. The spiral arm is mostly visible extending north ~1.5' and only slightly curving east. A short, low contrast section of the arm extends south of the bar. A second long thin arm nearly perpendicular to the bar extends south a similar 1.5'. It is also brightest at its origin on the east end of the bar. The arm only extends a short distance and blends into the low surface brightness glow of the halo on the north side. From north to south, the distance between the tips of the arms is at least 3'. Two mag 15 stars are at the NE edge and a collinear mag 15.5 star is off the NW arm.

This time of year we have an opportunity to view the best classic barred spirals in the sky -- NGC 1365 and NGC 1097 in Fornax, NGC 1300 in Eridanus, NGC 7479 in Pegasus and I would suggest adding NGC 1530 in Camelopardalis to this list!

Further reading:
2008 paper by Zurita et al: "Where are the stars of the bar of NGC 1530 forming?"

2004 paper by Zurita et al: "Ionized gas kinematics and massive star formation in NGC 1530"

2000 paper by Perez-Ramirez et al: "Circumnuclear regions in barred spiral galaxies. I. Near-infrared imaging"

GIVE IT A GO AND LET US KNOW!

NGC 1530 was one of my favourite galaxies for many years. I was dreaming about seeing its spiral structure as a child after I saw an old photo in a book. I drew it in 2012 using a 16" Dobsonian. The bar and the almost star-like nucleus were easy to see but the arms were pretty faint.

16", 196x, 2012, Ágasvár, Hungary:
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And an inverted, rotated and cropped version:
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Nice but overlooked spiral Steve, you are right. Perhaps because of the difficult arms for mid size telescopes.
Important to mention the dark lane which reaches in the core from the W. Very similar to NGC 1365 the dark lane was THE positive surprise to me beside the arms and counter arms. From the counter arms the W arm was visible more easily like the E counter arm extensions. With 27-inch all three details looks prominent even under soft seeing but good transparency. In the brighter E arm I could spot two HII regions. What I could not detect was the full, nearly 180° curving of the N arm around the DS.

27", 419x, NELM 6m5+, seeing III-IV
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My only observation of NGC 1530 so far is through Jimi's 48 inch this past October with Steve:

"Nice barred spiral - low surface brightness overall but a distinct spiral shape. 488x, 21.43 SQM."

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I'll note that this was a fairly quick look while the seeing was poor and the sky unusually bright - even so I'm mightily impressed by all the detail Uwe saw!

Further to Steve's comment about this being a great time of year to see the brightest barred spirals, we also looked at NGC's 1365, 1300 and 7479 through Jimi's scope this trip:

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Unfortunately we didn't look at 1097, so I guess that means we'll just have to go back next fall!

Uwe, those details are truly amazing on your 27" drawing!
I think the similar inner structure of NGC 1365 might be easier to detect as I could see it using another 16" scope (from Hakos, Namibia, see the drawing here).
Once we took a look at NGC 1530 in a 20" scope as well but we couldn't detect more details than you can see on my 16" drawing. But the conditions were far from perfect that time (some light pollution, low transparency, NGC 1530 far from culmination).

Howard, that's a beautiful collection of great spiral galaxies!

My observations of Saturday night (25 Feb) from SQM 21.4 skies with excellent seeing:

At 256x, 320x and 427x visible as a faint glow with an oval nucleus. Best seen at 256x. The nucleus points slightly south of the southern component of a faint double star that lies west of the nucleus. A very faint bar runs from south west to north east at an angle of about 120 degrees to the major axis of the nucleus. The bar is brightest at its ends. At the north end an arm runs east and at the south end an arm runs west. Both are thin and the northern arm is brighter than the southern arm.


Clear skies, Wouter