Object of the Week, December 22nd 2024 – M83, the Southern Pinwheel Galaxy

[akarsh]

M83 = NGC 5236 = MCG-05-32-050 = Southern Pinwheel Galaxy
Barred Spiral Galaxy in Hydra
RA: 13:37:01
Dec: -29:51:57
Mag (V): 7.52
Size: 13.8'×12.9'

I know you're asking yourself, how has this not been featured as the Object of the Week before! I was looking over the OOTWs in Hydra on Adventures in Deep Space and was surprised to see it so short and missing M83, so I have seized the opportunity to present a well-known object that is perhaps just a bit neglected due to its southern declination.


STScI-01EVT37HAEB2WGQ0DDR0A67PCY.jpg
M83 from the Hubble Space Telescope


The galaxy was discovered by Nicolas-Louis de Lacaille in 1751, before Charles Messier observed and recorded it as M83¹. It lies about 16 million light-years away from us². It is a grand design spiral galaxy. M83 is obviously very well-studied and the Wikipedia page happens to be well-written. The one interesting thing that stood out to me while reading that page was the potential interaction with NGC 5253, on which see Scott Harrington's OOTW post. M 83 is part of the Centaurus A–M83 galaxy group, which Scott helpfully annotated in his OOTW as consisting of Centaurus A, M83, NGC 4945 (Tweezers), NGC 5102 (iota's Ghost), NGC 5253 etc.

M83_POSSIBlue.jpeg
M83, POSS I Blue Image (it is overexposed on POSSII Blue)

Visually, the striking feature of M83 is certainly its beautiful grand design spiral arms, studded with star-forming knots and its prominent bar.

I first looked at this galaxy on December 27th 2005 from a village south of Bangalore, where I logged it through my ATM'd 8" f/8 as "Terribly faint face-on spiral" and noted that its surface brightness was similar to M 33. Three nights later, we were prospecting a new observing site in a village north of Bangalore where we encountered much better conditions. My logs show a lot of excitement around the sky, and the entry on M83 reflects that: "Significantly brighter! We could probably see the spiral arms!" I vaguely remember having seen it through 10×50 binoculars, but have no log entry.

Those of us who were on the field of Texas Star Party (TSP) 2012 (I spy Jimi, Alvin and others) will remember those special nights. It being my first ever time at TSP, I thought it was just another night and was very very impressed with the views. It certainly wasn't your average TSP night. The reason I mention this is that I still remember being very impressed by M83 that night – great conditions really make a difference. I logged, with my 18", "Bar, lots of spiral arms, mottling! Was not a uniform glow even in 8×50 finder."

My most recent observation was from a SAC site near Phoenix, Arizona. The sketch through my 18" shows a bright core with a bar running SE-NW. The bar gets brighter where it meets the spiral arms, and the galaxy appeared heavily mottled all over. Two tight spiral arms were discerned, going counterclockwise from the ends of the bar. The starting portions of two other spiral arms were also picked up. Here is my sketch:

M83_knots.jpeg
(I renamed A as #1, B as #2, C as #3 below so my designations are not confused with any official designations)

As you can see, I logged three knots, but it's hard to correlate the rough sketch to images and identify exactly which knots on the image correspond to the sketch. My best guess is the following:

Knot #1: 13:36:43.3 -29:52:19 ~ [RK83] 266
Knot #2: 13:37:04.2 -29:49:23 ~ [RK83] 113
Knot #3 (suspected): 13:37:01 -29:54:24 ~ [RK83] 144

M83Knots.jpg
Above knots marked on the POSSII Red image


The designations are HII regions plotted in SIMBAD or NED from Rumstay and Kaufman 1983 that were roughly aligned within the knots. Knot #1 was most prominent followed by knot #2.

Out of curiosity, I looked up the M83 Group in SIMBAD and it lists 13 members. I wanted to know what is the nearest dwarf galaxy towards M83 to see if it was tractable. It happens to be PGC 166170 which I wish you the very best of luck with, because there seems to be nothing visible on the DSS2 imagery! The next closest one seems to be ESO 444-78 which seems to have some hope of yielding.

GIVE IT A GO AND LET US KNOW


References:
1. Courtney Seligman's website on NGC 5236
2. Redshift-independent distances for M83 from NED

[Howard B]

Unfortunately, I have only two observations of M83. The first is from 1993 with my old 20-inch Obsession:

"Large with faint outer area and a fuzzy stellar core. Seemed asymmetrical with a bar going through its central area and into its faint outer area. It was near the horizon in the glow from Portland (Oregon) - would be great in a darker sky! 143x."

The second is from 2013 with Jimi and his incredible 48-inch scope:

"Holy cow, now this is an amazing spiral galaxy. Probably more detail than M51 - spiral arms, knots, streamers, dark lanes, central bar - everything. My goodness, I need to make a BIG sketch of this! 375x, 21.60 SQM."

I also remember how much faint detail there was in between the spiral arms - it was a fantastic sight. Sadly, I haven't sketched M83 yet...

[Raul Leon]

Hi, here's my observation from 5/19/2012: On a night of mediocre seeing, Messier 83 galaxy in Hydra ; mag: 7.6 ; size: 13.8' x 12.9' ; very bright and large ; bright central bar with brighter core ; I used a 10mm Radian at 200x with my 14.5 StarStructure f/4.3
m83.jpg

[Steve Gottlieb]

I've made numerous observations of M83, but I'll highlight three of the more memorable ones from very different locations.

13.1" (2/19/04, Costa Rica): this impressive galaxy was viewed carefully at both 105x and 166x. The overall size including the spiral arms are ~8'x6'. The halo is broadly concentrated then rises sharply to an intense 25" core that increases to the center. Complex spiral structure is quite obvious. A spiral arm is attached on the east side of the core and wraps around the south side of the galaxy in a counter-clockwise direction. A second arm is attached at the south side of the core and winds to the west a bit on the south side. Finally, an arm is attached on the west side and shoots north before gently bending east along the north side of the outer halo. This was using a highly compact 13.1" travelscope that I checked in as my luggage.
---

24" f/3.7 (4/11/08, Australia): M83 resembled the photographic appearance in the 24" at 200x. The bright "bar" was elongated SW-NE and roughly 3'x1' in size with a well-defined bright, round core, 1' in diameter. The first prominent arm is attached at the northeast end of the bar and sweeps south (counter-clockwise) on the east side of the core, wrapping around the southeast side and spreading out a bit as it terminates to the south of the core (~3' from the center). This arm has a high contrast along its outer edge and a couple of faint stars or HII knots are visible near where it attaches to the bar. On the southwest end of the bar a second prominent inner arm emerges and abruptly wraps counter-clockwise around the galaxy on the west side as it heads north. This arm continues to wrap around the north side before spreading out on the northeast side and merging into the outer halo ~3.5' from center on the northeast edge of the halo. A third, more ill-defined arm, also emerges from the core on the south but sweeps more gently to the west (instead of heading north) on the outside of the second arm. It spreads out and fades into the general glow about 3.5' SW of center near a superimposed mag 12 star. Offshoots of the main arms are difficult to trace and contribute to the general background glow of the halo.
---

48" (4/7/13, Texas): During this observation of M83, I focused on the HII regions that light up portions of the remarkable spiral arms that emanate from the 3'x1' central bar. The bar is sharply concentrated with a small, intensely bright, 1' round core. At the NE end of the bar, a high contrast arm begins to sweep counterclockwise along the E side, ending up directly S of the core. Several knotty clumps were visible in the region where the arm is attached. First, at the NE end of the central bar [1.2' NE of center] is NGC 5236:[dPD83] 42, a 10" HII knot. This designation is from a 1983 paper by de Vaucouleurs, Pence and Davoust that includes a map of the 60 brightest HII regions. Close east of this knot is #46, a 20"x10" elongated patch, situated where the arm begins to unfurl to the south [1.7' NE of center]. HII region #54 is another 12" knot a bit further southeast [0.6'] along the arm [1.9' ENE of center].

At the opposite SW end of the bar, a prominent second arm emerges and spirals out counterclockwise along the west side of the galaxy heading north and then spreading out as it curves east. The arm dims noticeably on the NE side of the halo near a mag 13 star and has a low surface brightness as it continues south in the outer halo, heading towards HJ 4599, an 8" pair of mag 8.2/10.7 stars. Several knots are visible in this arm. As the arm emerges at the SW end is #22 and #18, a small 10" knot [1.8' SW of center]. Close north is an elongated clump [2.0' WSW of center], ~25"x10", containing #13 and #15. Another elongated patch, 30"x10", containing #12 and #16, is 1' further north along the arm [1.9' WNW of center]. Additional HII regions were visible at the northern side of the arm; #39 and #43 are a close pair of small knots ~2.5' NNE of center. Further east along the arm [3.3' NE of center] is #56, another elongated patch, 20"x10".

A third, wider and more diffuse arm begins on the south side of the bar. It extends below the brighter arm on the west side, and sweeps more gradually, forming an outer western arm. This arm passes just north of a mag 12 star and ends about 4' W of center at a brighter, elongated patch that includes #2 and #3, as well as a mag 15 star.

[cloudbuster]

During my 2022 Namibia trip I observed and sketched M83. Here the majestic galaxy is almost in zenith when it culminates and it showed! The central bar is easily seen, as well as the inner spiral arms. Together they form the greek letter “Theta”. At the end of the N-arm (under in the sketch) some concentrated nebulosity is seen and from here a soft spiral arm bends up, curling along somewhat brighter stars. On the W-side (left) more arms join, of which the lower one is the brightest. The field at this low magnification is littered with stars, some of them as foregrounds stars on the face of this beautiful galaxy. Sketched with a 16? Dieter Martini dobson @129x.

M83.jpg

[kisspeter]

Drawing M 83 with a 16" in Namibia (Hakos) in 2012 was a turning point for me. This is an absolutely amazing galaxy. I can still remember as the details unfolded in the eyepiece after 4-5 hours of intense drawing. Like the tiny dark regions in the bar. I was in a hurry with the drawing because I had so many other objectives. After the starfield (2-3 hours) drawing the galaxy itself was pure joy for a couple of hours. This was my most detailed and most spectacular drawing at that time.
m83_kisspeter.jpgm83_kisspeter_positive.jpg

In 2016 we took a look at M 83 with the 24" at Hakos, Namibia. The bigger scope showed so much more detail. The view through the eyepiece very much resembled the POSS I photo Akarsh linked above. Just incredible.

I have an earlier observation as well from Hungary, Central Europe. We went on a hiking trip before our high school exam and I also took my little 4" Dobsonian. I could clearly see the bar and the start of the spiral arms, though very faint. No more but I still have good memories from that night of observing in the hills.

[Uwe Glahn]

To M 83 I had two memorable moments.

First night was 18 years ago at the highest accessible road in the Alps (9600 ft) with an incredible transparency this night. We observed M 81 with naked eye this night and the milky way in Scorpio looks like clouds. M 83 rises only around 10° above the horizon and is always heavily soften because of the extinction. But I had my best view from the northern hemisphere.

sketch: 16", 129x, NELM 7m0+
M83.jpg

Second night was on the Gamsberg/Namiba, maybe one of the best observing places on earth. I had the opportunity to use the 28-inch telescope. The use of this heavy parallactic mounted newton was a little bit tricky. I felt like Lord Rosse between his two large walls. But thw view was stunning.

sketch: 28", 312x, NELM 7m5+
M83_28.jpg

[Howard B]

Hey Uwe - wow! What a fantastic sketch with the 28-inch scope!!

[Uwe Glahn]

Thanks, Howard.

Critical I'm always be with my own results, I favor Peter's result over mine. He captured the wider NW arm, I missed because of the two high magnification and too low EP?

[Howard B]

I know what you mean - it difficult to see and sketch everything! Both yours and Peter's sketches are marvelous though.

[ScottH]

"I know you're asking yourself, how has this not been featured as the Object of the Week before! I was looking over the OOTWs in Hydra on Adventures in Deep Space and was surprised to see it so short and missing M83, so I have seized the opportunity to present a well-known object that is perhaps just a bit neglected due to its southern declination."

Um, actually, my first thought was...why should I be looking at this in December!?!

I just poked around and it seems that most sources quote Lacaille having found the galaxy in February 1752. But some do say 1751, so presumably it was in the winter of 51/52?

As far as "large" spiral galaxies go, I've finished tearing into M31, M33, M51, M74, NGC 6946. This spring I hope to finish with M101. I don't know if I will ever be finished with M83 until I've seen it from the Southern Hemisphere. However, I will say that the one star cluster I've seen in my 10-inch is [WCK2011] 46, meaning it's the brightest one.

M83 SSC.jpg

[akarsh]

"I know you're asking yourself, how has this not been featured as the Object of the Week before! I was looking over the OOTWs in Hydra on Adventures in Deep Space and was surprised to see it so short and missing M83, so I have seized the opportunity to present a well-known object that is perhaps just a bit neglected due to its southern declination."

Um, actually, my first thought was...why should I be looking at this in December!?!

I just poked around and it seems that most sources quote Lacaille having found the galaxy in February 1752. But some do say 1751, so presumably it was in the winter of 51/52?

As far as "large" spiral galaxies go, I've finished tearing into M31, M33, M51, M74, NGC 6946. This spring I hope to finish with M101. I don't know if I will ever be finished with M83 until I've seen it from the Southern Hemisphere. However, I will say that the one star cluster I've seen in my 10-inch is [WCK2011] 46, meaning it's the brightest one.

M83 SSC.jpg

Ah! Mr. Extragalactic Knots himself, I knew you'd have something to bring within the galaxy.

Yeah, I picked it after seeing Hydra cut the meridian in my early mornings, but I didn't remember that Hydra is the longest constellation east-west and clearly the head of Hydra may be high up before dawn but looks like M 83 currently transits during nautical twilight. Oops.