- Art by Judy Schmidt

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Note: For the latest Hubble processing, try my Flickr gallery. My website is updated less often.

NGC 1569: Realm of Starburst (Hubble Processing)

NGC 1569: Realm of Starburst

Here’s something done a little differently. The datasets for this brilliant little galaxy are somewhat awkward to compose an image with. There’s near-infrared, red, some H-alpha, and some old WFPC2 green, H-beta and [OIII] available. Long story short, if you try to put them together it almost doesn’t matter what way you do it—funky colors ensue. There’s not enough blue to balance out the image even if you stack all the old WFPC2 imagery together, which I did. In the end, I made those lovely clouds H-alpha purple. I think it looks pretty good. It’s not typical at all, but sometimes you just have to throw out conventions to solve a puzzle. Once I decided to ditch red as an option for the H-alpha, everything fell together quite nicely.

If you prefer a more “natural” treatment of the colors, check out the HubbleSite press release image. Maybe you’ll notice the interesting greenish halo around it. That’s what I mean by the filters being hard to work with.

Previously I posted a close-up image of the three superclusters in this galaxy. You can sort of see them in this picture but they’re all blown out from being overexposed at observation so if you want to see the clusters better, head over to the supercluster image for a more detailed look.

Red: HST_10885_01_ACS_WFC_F814W_sci
Green: HST_10885_02_ACS_WFC_F606W_sci
Blue: hst_08133_01_wfpc2_f547m_wf_sci + hst_08133_01_wfpc2_f502n_wf_sci + hst_08133_01_wfpc2_f487n_wf_sci
Violet: HST_10885_06_ACS_WFC_F658N_sci1

North is NOT up. It is 23.3° clockwise from up.

Super Clusters in NGC 1569 (Hubble Processing)

Super Clusters in NGC 1569

A recent thread at Asterisk (this is APOD’s discussion forum) got me looking at this beautiful object and the data in Hubble’s archive. I noticed there was a very intimate look at the center of this starburst galaxy featuring many bright, young stars comprising super star clusters and decided to process it, making sure not to over brighten the star clusters so that as many details would remain preserved as possible.

In the center is Cluster A, which is actually two clusters which are called A1 and A2. At lower left, the next brightest cluster is called Cluster B. To the upper right is Cluster C, which is somewhat enshrouded in nebula.

Other star clusters are also visible as dimmer, soft yellow blobs which almost look like elliptical galaxies because it’s very hard to make out any individual members. I’m not sure what kind of star clusters those are. To me they look a lot like small globular clusters. One may be tempted to conclude that we are seeing the life cycle of globular clusters in some kind of holy grail moment, but something tells me that if that were the case it would have made headlines somewhere. Our knowledge about the formation of globular clusters is murky at best. Does NGC 1569 offer any insights?

This image is possible thanks to the following HST proposal:
Starburst Galaxies and Their Population of Super Star Clusters

Red: HST_10885_06_ACS_WFC_F658N_sci
Green: HST_9300_02_ACS_HRC_F555W_sci
Blue: HST_9300_02_ACS_HRC_F330W_sci

North is NOT up. It is 18.4° clockwise from up.

Lonely Lenticular (Hubble Processing)

Lonely Lenticular

This galaxy was imaged as part of the Coma Cluster survey before the ACS suffered an electrical problem and failed in the middle of this work, leaving the survey only 28% complete. This galaxy is not in the midst of the cluster but rather on the outskirts.

Identified as PGC (principle galaxy catalog) 83677, the symmetrical shape is neither spiral nor elliptical, but rather something in between. Little if any star formation is occurring and perhaps one day this lenticular galaxy will lose its disc shape, rings, and bar to become a smooth, spherical elliptical. It seems very serene to me with its old stars glowing calmly and its lack of close neighbors.

However, not all is quiet. Within the galactic nucleus, an active black hole is likely present, evidenced by its brightness in x-ray and ultraviolet wavelengths.

The saturation of the colors in this image has been increased to make the oranges and cyans more apparent.

This image is possible thanks to the following HST proposal:
An ACS Treasury Survey of the Coma cluster of galaxies

Red: HST_10861_78_ACS_WFC_F814W_sci
Green: Pseudo
Blue: HST_10861_78_ACS_WFC_F475W_sci

North is NOT up. It is 45.1° clockwise from up.

Cosmic Smudge (Hubble Processing)

Cosmic Smudge

This asymmetrical congregation of stars is nearby dwarf galaxy NGC 4789A, seen at a distance of about 4 Mpc or around 14 million light years. The colors here are greatly emphasized and so the galaxy appears quite blue. There does appear to be some star formation going on, so the coloration is not totally misleading. However, some bluish, nebular patches would be much better represented by red, signifying the emission of H-alpha from those clouds. There is no H-alpha data available for me to make that change to the image, unfortunately, so the current processing will have to do.

For this picture I also used a new technique to try to increase the color variation since it is only a bicolor image. Bicolor images are usually presented in orange and cyan, which can otherwise be described as a red and blue channel with the green generated by averaging the red and blue together. I have done just that with this image, but additionally I adjusted the purest cyan and purest orange parts to be more blue and more red, respectively. I think it worked very well, especially for those background galaxies.

The chip gap has been filled with cloned data. It is located horizontally at around the bottom 5th of the image. Several background galaxies intersected it and for three of them interpolated their missing parts by copying and rotating them 180° to complete their missing halves.

My friend’s cat died recently so I named this image after her cat whose name was Smudge. If you would like to see Smudge, a video of her being adorable is available here.

This image is possible thanks to the following HST proposal:
The Dynamic State of the Dwarf Galaxy Rich Canes Venatici I Region

Red: HST_10905_15_ACS_WFC_F814W_sci
Green: Pseudo
Blue: HST_10905_15_ACS_WFC_F606W_sci

North is NOT up. It is 55.4° counter-clockwise from up.

MACS J0717 (Epoch 2) (Hubble Processing)

MACS J0717 (Epoch 2)

This is the final culmination of 154 Hubble orbits of observation for MACS J0717. Not a huge difference from Epoch 1, but it’s deep enough now to see some even fainter details. Plus I think I processed it even better this time. It looks smoother to me. The sinuous blue background galaxies are a little brighter and easier to see.

Looking at the largest elliptical galaxies, almost all of them are perturbed in some way, like they have recently consumed or interacted with a smaller neighbor. The shells which align more or less neatly with the long axis of them are indicative of absorption of a much smaller galaxy, which seems to be the case for all of the interacting ellipticals. One can almost imagine if time were sped up that this cluster would be a roiling ball of activity with the largest galaxies consistently snacking on smaller morsels. Also visible are many lenticular galaxies, seemingly devoid of star formation but still maintaining some semblance of their past spiral selves.

It is difficult to unflatten this image and imagine its depth. If you would like to try, then of course you should place the approximately 11 Milky Way stars in front. Then, imagine that many of the brighter, whiteish, undisturbed spirals are probably in the foreground. They are smaller and your brain would like to think that all smaller things are behind the larger ones, but that is not always the case. If they were in the cluster, they would probably be gravitationally disturbed and if they were behind, they would be strongly gravitationally lensed. It is difficult to differentiate them but this is a good way to do it visually, even if it is not terribly accurate. Next comes the massive cluster itself. One appreciates the massive dimensions of the elliptical galaxies knowing that they are more distant but still just as large or even larger than the foreground spirals. Finally, those hairlike streaks are all behind the cluster. Most of the smaller, dimmer objects are also very likely behind.

I previously posted the Epoch 1 data here.

Datasets can be found here:…

Red: WFC3/IR F105W + F125W + F140W + F160W
Orange: ACS/WFC F814W
Cyan: ACS/WFC F606W
Blue: ACS/WFC F435W

North is NOT up. It is 54.6° clockwise from up.

NGC 4889 (Hubble Processing)

NGC 4889

A dominant member of the Coma Cluster, remarkable elliptical shell galaxy NGC 4889 looms large over its domain. Within the cluster, only NGC 4874 (not shown) is brighter, and only just barely.

The faintly visible shells of the galaxy are evidence that the monstrous galaxy recently merged with a smaller galaxy.

Other details to notice include smaller and/or more distant elliptical galaxies, some of which are ghostly and faint. I have seen them called them fluffy galaxies in this recent press release. The nature of these ultra-diffuse galaxies and specifically how they manage to form as they do is still a matter of speculation.

Very few Milky Way stars are visible within the field. As usual, the ones with four spikes are most likely foreground stars. The hundreds of tiny, fainter point-like objects are globular clusters, many of which are likely orbiting NGC 4889.

Do you think that maybe some background galaxies show a curious alignment? You might not be imagining it. It’s possible that some weak gravitational lensing is going on. Weak gravitational lensing is detectable by taking measurements of all the background galaxies and seeing if they all seem a bit squished in a certain direction.

One final curiosity that I would like to note about NGC 4889: If you measure the brightness of the center of its nucleus, it is actually not as bright as NGC 4886, which is the smaller elliptical galaxy just above it in this image (that one skinny galaxy is kind of pointing toward it). The way some elliptical galaxies have diffuse cores while others have very sharp ones is something that perplexes me. It seems that even though NGC 4889 is much larger than NGC 4886, its nucleus is notably less dense than NGC 4886’s.

Red:  ACS / WFC F814W (jb2i02020_drc)
Green: Pseudo
Blue: ACS / WFC F475W (jb2i02010_drc & jb2i03010_drc)

North is NOT up. It is 43.6° counter-clockwise from up.

UGC 3351 (Hubble Processing)

UGC 3351

This galaxy is contained in what I would call one of the saddest-looking datasets in the archive. It had very little hope of ever making its way out to the public eye because of the chip gap running through it and also because there isn’t enough data available to make a nice, color image.

So anyway, I did what I could with it. I have eked out some color by taking the near-infrared filter in grayscale and overlaying the available H-alpha data on top in red so we can see those little red clouds.

I also sharpened the dust clouds a bit because that is what makes this galaxy visually interesting. It is quite dusty, isn’t it? The dust darkens the galaxy enough that even that nearby dim star easily outshines even the brightest visible part of the galaxy’s slightly bulging nucleus.

The chip gap was filled with cloned data. I can see an entire star and most of one small background galaxy are lost in the infernal chip gap. Alas.

This image possible thanks to the following HST Proposal:
The Nuclear Structure of OH Megamaser Galaxies
(Oh, what in the Universe is an OH megamaser? I should have read that before posting this…)

All channels: ACS / WFC F814W
Red overlay: ACS / WFC FR656N (That’s a ramp filter)

North is NOT up. It is 86.44° clockwise from up.

Impression of a Three Armed Spiral (Digital Painting)

Impression of a Three Armed Spiral

An illustration of a three armed galaxy based on a real one only visible as a faint fuzzy in the background of one of Hubble’s images. The original Hubble image of the galaxy looks like this. We might never see a better picture of it and I wanted to try an illustration. I used textures and other background galaxies from the dataset of MCG+07-33-027. Many small details were hand painted, such as the little pink clouds of H-alpha.

NGC 4278 & 4283 (Hubble Processing)

NGC 4278 & 4283

This is a five panel mosaic of a pair of elliptical galaxies: NGC 4283 on the left and NGC 4278 on the right. Many background galaxies are also visible. In general, the fuzzier, more extended ones are background galaxies while the sharper, more point-like ones are globular clusters encircling NGC 4278. Interloping Milky Way stars are largely absent, but I think I see a few very dim ones.

There were some Chandra observations of NGC 4278 showing that several of the globular clusters are glowing in X-rays. (Yes, that’s Andromeda. The picture of NGC 4283 can be found in the right side column)

The blank corners are the edges of the fields where no data is available. Not too bad except for the upper left where it is extra noticeable next to NGC 4283. Chip gaps were filled with cloned data.

Two HST proposals related to this image are available:
Probing The Globular Cluster / Low Mass X-ray Binary Connection in Early-type Galaxies At Low X-ray Luminosities
Probing The Globular Cluster / Low Mass X-ray Binary Connection in Early-type Galaxies At Low X-ray Luminosities

Yes, they both have the same title. The second finished up where the first left off. I think it got interrupted by the ACS’s electrical problems. Good to be able to pick back up afterward thanks to some nice astronauts. You can see the noise stripes in the upper left field which started appearing after the mission which repaired the ACS. All the others were taken prior to Servicing Mission 4.

Green: Pseudo
Blue: ACS WFC F475W

North is up.

UGC 4879 (Saturated) (Hubble Processing)

UGC 4879 (Saturated)

In the bottom half of the frame here is isolated dwarf galaxy UGC 4879, imaged in wideband red (606 nm) and near-infrared (814 nm) light. Each channel was exposed for nearly 19 minutes each which results in a nice, deep picture of both the relatively nearby dwarf and a good number of pleasant background galaxies.

Along with a fairly raw and conservatively processed image of the galaxy which appears nearly grayscale I have included a color-saturated version so that it is more easy to see the younger, brighter, bluer stars at the center of the galaxy and the older, redder ones spread around the outside.

I was scanning through the papers related to the Hubble proposal for which this galaxy was imaged and was pleased to see that it has a few papers devoted to just it. Oftentimes when things are part of a survey they don’t get special attention unless they stand out. What makes this dwarf special is its isolation from other galaxies. If I understand correctly, the idea here is that if it’s far away from everything then astronomers can look at the life cycles of stars without some other galaxy coming along to confuse things by adding on some extra history to account for. Some very old stars have been found in the outskirts of the galaxy. If that interests you, then check out the ADS links at the proposal page: Resolving the Smallest Galaxies with ACS (HST Proposal 11584)

Red: ACS / WFC F814W (jb3c10020_drz.fits)
Green: Pseudo
Blue: ACS / WFC F606W (jb3c10010_drz.fits)

North is NOT up. It is 22.11° counter-clockwise from up.

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