Note: For the latest Hubble processing, try my Flickr gallery. My website is updated less often.
This is one of those beautiful clouds of dust with stars peeking out, forming, and interacting with it in various ways. It’s a small cloud located about 2° NW of Aldebaran. For context you can see the cloud in this image on the right. It is the first dark reddish puff of dust closest to the bright yellow star in the lower right corner.
If you could watch it over many years, you would see that red jet emanating from HL Tauri in the upper center blow onwards, pushing around the dust with it. You’d notice the T Tauri variable stars XZ Tauri on the left flare violently. Dual jets would continue to flow from the interesting object in the lower right. Over thousands of years, perhaps the dust will disperse to reveal a small cluster of young stars.
This polarized version of HL Tauri was put together so that I could use a sliver of it to help fill in the chip gap on this. I did that and I also interpolated (read: made up) data for the rest of the chip gap. Hubble processing woes.
This is reprocessed data of an image I already did which won 3rd place in the Hidden Treasures contest which spawned this hobby of mine. See previous version here.
Red filter (F625W) was placed into all three channels to form a grayscale image. Upon that, H-alpha data was overlaid in red, orange, and yellow hues. I think this looks more realistic than my previous version which simply used a red, pseudogreen, and blue scheme, though it was probably easier to differentiate the H-alpha from the red light in that version.
Red: HST_9863_01_ACS_WFC_F625W_sci +HST_9863_01_ACS_WFC_F658N_sci
Green: HST_9863_01_ACS_WFC_F625W_sci +HST_9863_01_ACS_WFC_F658N_sci
North is NOT up. It is 30.1° counter-clockwise from up.
I’m not totally sure what the intended target for these observations was. Probably none of these galaxies. What was being looked for here were protocluster galaxies (Proposal 10404) and what eventually came out of it was the aptly named Spider Web Galaxy. The Spider Web Galaxy is actually a few arcminutes north of this little group, which reminds me of one of our famous stellar asterisms otherwise known as constellations. It could be a galactic version of Delphinus. The asterism is actually pointing almost due north (to the left).
A widefield, north up version is available.
Red: F775W ACS/WFC
Green: F606W ACS/WFC
Blue: F435W ACS/WFC
North is NOT up. It is 69.5° counter-clockwise from up.
NGC 1783 (Hubble Processing)
Intermediate age globular cluster in the Large Magellanic Cloud. I tried to guess a little better at what color this thing should be overall instead of going about it in a wholly arbitrary way but it’s still just a guess, even though I tried to use some math. I should probably find someone to ask for a clue on this because there must be a way to process things more accurately.
It looks a bit yellowish. If I had done this the way I usually do globular clusters, I would have made the overall color be as close to neutral as possible. Some especially red stars are almost invisible in the blue channel, shining most strongly in the near-infrared wavelength (F814W). There is a small group of blue stars at the lower edge of the frame. A tantalizing spiral galaxy is peeking out from behind a couple of bright stars near the middle right edge of the frame.
Conveniently, three wideband channels of color were available which is invariably more pleasant to look at than a two channel image with an interpolated green channel.
These data were collected by the Hubble Space Telescope as part of Proposal 10595 - A Reference Database for Accurate Ages and Metallicities of Globular Clusters in the Magellanic Clouds
North is NOT up. It is 37.6° clockwise from up.
NGC 3818 (Hubble Processing)
Looking over this elliptical galaxy in preview at the archive, at once I was struck by the sheer desolation of it. A casual observer will pass over this as just another boring elliptical. It lacks the personality of a spiral galaxy. It has few “friends” in the field, either in actual close proximity to it pretend friends from our Milky Way to occupy the field. This isolation is good. Without all the clutter, subtle details about the galaxy emerge. Nearly every fuzzy little white dot in the halo around this galaxy is part of the galaxy—ancient and mysterious globular clusters. The galaxy is not as smooth anymore. It does have tiny friends. Where did they come from? Why didn’t they smooth out with the rest of the galaxy? Are they in any special arrangement?
Visually, there is not a lot to occupy one’s mind. I thought of other things. These data are beautiful. The quality of Hubble data is almost always high but often in this telescope’s frantic lifetime there is no time for negligible details. A minimum of four separate exposures is required to easily eliminate most cosmic rays. Quite often, this simply does not happen. A minimum of two separate filters must be used to generate a color image. Happily, this bit is usually satisfied. The exposures must be dithered in a certain way to ensure the chip gap is covered. Depressingly, this does not happen often because there isn’t enough time to do enough exposures. This is all just satisfactory for scientific analysis. Hubble and its operators can’t be blamed.
We need more telescopes like Hubble and we need more professional observatories taking the extra effort to release their data to the public in a way that is easily accessible. We just celebrated the arrival of ESA’s Rosetta at comet 67P/Churyumov–Gerasimenko. Last night NASA’s MAVEN joined the Mars family of science instrument in orbit and on land. One of these missions will return raw data which will, within one year, be released for mass consumption by an eager public of amateur astronomers and space enthusiasts. The other is bogged down by petty politics. You can’t just complain about people being uneducated and ignorant if their access to data is stunted. Why are there so many athletes and sports fans? Well, it’s because there are thousands of stadiums built around the world. Virtually every kid has access. “If you build it, they will come.”
I am not delusional enough to think astronomy as a profession or hobby will ever be as popular as sports, but I do think there are improvements that could be made by scientists and organizations. If you release the data and encourage people to get involved with it, some more astronomers might just be born. NASA’s open policy is admirable. ESA’s leaves much to be desired and they’re not alone in that regard. I might be in a minority opinion on this and I’m not the one footing the bill on any of these expensive observatories but I’m very thankful that Hubble is operated by NASA in partnership with ESA and that means that it is part of NASA’s policy to release any proprietary data within one year. It’s a great thing. Science shouldn’t be reserved for the privileged. Not in this century. Not with the Internet and computers as accessible as they are. All I wanted to do was create some pretty pictures at the beginning but it’s grown into much more than just that.
These data were collected for Proposal 10554, “Globular Cluster Systems of Elliptical Galaxies in Low Density Environments
HST Proposal 10554”
North is NOT up. It is 25.5° clockwise from up.
NGC 45 (Hubble Processing)
This could be the poster child of low surface brightness galaxies if the Triangulum Galaxy (M33) didn’t take that place already. I find it to be exceptionally diffuse, even more so than M33, but it also has a clear spiral structure and is also large enough that amateurs can also easily observe it. A lot of LSBs are simple irregular dwarfs amounting to nothing more than the faintest of nondescript smudges. See: Rob Gendler’s, James Foster’s, and Bernd Flach-Wilken’s. There are more but I just picked the first three in the result list. Hubble’s version provides a lot of detail but the amateur images are perhaps more pleasant to view, capturing the whole galaxy and not being riddled with cosmic rays and noise like this image.
I actually tried working on these datasets a long time ago thinking it was some glorious, missed spiral galaxy in the archive because the thumbnails at the HLA (Hubble Legacy Archive) are deceptively bright. When you open the FITS file expecting this grand design to illuminate your screen, it’s a pretty big letdown to be confronted with this strange, dim creature. Now that I understand low surface brightness galaxies a little better, I am interested in them and I want to share them with everyone so it was time to revisit the data. It’s still a bit ugly but it’s not the galaxy’s fault. There just aren’t enough exposures to easily remove the cosmic rays and it’s really quite noisy as well because of this. There’s not much that can be done to fix the noise and I got rid of the CRs as well as I could.
These data were acquired for Proposal 9774 “Young Massive Clusters in Spiral Galaxies and the Connection with Open Clusters”
Chip gap filled with some WFC3 / UVIS data from Proposal 13364.
North is NOT up. It is 60.8° clockwise from up.
Leo A (Hubble Processing)
An important dwarf galaxy that you’ve probably never heard of said to be made of the primordial stuff of galaxies. Taken straight from the proposal (10590) for this image:
“Leo A is the best nearby candidate to be a redshift zero analogue to the major building blocks of the Milky Way.”
So, there you have it. If you want to study galaxy formation, I assume that it helps to have data on stuff like this.
I only wish that the composition and chip gap had a more satisfactory solution. The edges of the galaxy didn’t quite fit on the detector and some older WFPC2 data was available to fill the chip gap but only half of it. It’s hard enough to get people interested in what is most likely the commonest type of galaxy in the Universe without these aesthetic insults to hamper attempts at it.
Still, these data were quite comprehensive and with no less than 8 sets available for both channels, an incredibly smooth and cosmic-ray-free result is possible with minimal effort. It’s give and take in the world of limited Hubble time.
Red: Median stack of 8 ACS / WFC F814W panels
Blue: Median stack of 8 ACS / WFC F475W panels
Chip gap filler:
North is NOT up. It is 12.4° clockwise from up.
NGC 3516 (Hubble Processing)
There are two reasons why this galaxy is interesting aside from the fact that it is one of those neat, geometric lenticular galaxies. First, as a Seyfert I type, it has an active nucleus. Rick Edelson has an easy to read article on that aspect and its variability here. If you want something harder to read, you might try X-ray Characteristics of NGC 3516: A View Through the Complex Absorber by T. J. Turner et al, which I think also mentions the second interesting thing which is easily seen in this picture. There are some blue clouds of gas to go along with those darker strands of dust near the nucleus.
I’ve learned that if you see something glowing blue in space, it’s probably doing that because of ionization. Given the crazy amounts of energy being output by the active nucleus, it’s not surprising that it happens, but I admit that it seems crazy that it is able to have this effect reach so far out from it. Anyway, I don’t understand it very well, so take my explanation with a grain of salt.
Smallish dots of light scattered around I presume to be globular clusters associated with the galaxy. They are conspicuous given how otherwise smooth the galaxy appears.
Note that though the blue clouds were only visible in the blue channel (F450W) they appear bright and almost white in my image. I did this to make them easier to discern. Anytime something is present only in the blue channel it tends to get lost against the background.
Another thing to note is that I aggressively sharpened the dust and these blue features. They are easy to see in reality but increasing their contrast allows us to see the fainter parts much more easily.
Furthermore, only the center of this image is in color as the nucleus was imaged in 1998 by Hubble’s WFPC2 as part of a study on barred bulges of lenticular galaxies. Later on, the whole galaxy was captured by Hubble’s WFC3/UVIS instrument in a subsequent study to measure the bulge luminosities of AGNs. Combining these two datasets, color can be generated for the center and the whole galaxy structure can be included in black and white which is ok because there really is not a lot of color away from the nucleus, anyway.
Green: WFC3 / UVIS F547M (ib5e02010_drz)
North is up.
NGC 339 (Hubble Processing)
Just a quick globular cluster. This one is in the Small Magellanic Cloud. Some background galaxies are scattered between the stars. The most prominent one is an elliptical galaxy in the upper left but there are a lot of spiral and lenticular disks peeking through as well.
This was part of a study on star clusters in the SMC measuring ages of stars and a bunch of other stuff I will not attempt to paraphrase because I’ll probably get it wrong. See for yourself here*. Thanks, people who did proposal 10396!
North is NOT up. It is 43.8° counter-clockwise from up.
This is a very young star cluster located within the Carina nebula. These are newly formed stars and we are peering at them through a reddening nebula of dust and gas. The longpass near-infrared filter cuts through much of the nebula and reveals many apparently dimmer stars as reddish pinpricks of light. I have adjusted the colors so that the brighter, whiter stars and their surroundings appear bluer because this is a young cluster. In reality, they are at least a little reddened.
Another interesting view of this cluster was done using the Very Large Telescope at the European Southern Observatory. I think it is a great example of the power of adaptive optics. You can use that funny string of six stars in the middle right to help orient yourself.
There is an interesting arc of cloud at the bottom edge of the frame. A paper discussing its possible nature is available.
Many long hours were spent carefully removing charge bleeds to the best of my ability. The closeness of the stars to one another meant that there was much overlapping of diffraction spikes and charge bleeds which compounded the situation. Not the hardest thing in the world to deal with but it is tedious and I found it difficult to concentrate for long periods of time on the task. Cosmic rays are easier. I can throw on some music and zone out while dotting them away. There were a few very nasty filter ghosts that had to be dealt with. I ended up using the Ha data, which had no such problems, to compensate for these large anomalies in the green and blue channels. This is not an ideal solution but it is better than nothing and it is also a little better than what I usually do, which is to manually darken them with a masked curves adjustment layer. The problem is that the Ha of course looks very little like an f550m or f435w filter except for the placement of the stars and some vague details of the nebula. In particular, it was very helpful in clearly revealing that nice, dark globule which was severely compromised. Anyway, I did the best that I could.
This image is possible thanks to the collective efforts of individuals involved with proposals 10602 and 10241.
Red: HST_10602_a1_ACS_WFC_F850LP_sci + hlsp_carina_hst_acs-wfc_14_f658n_v1_sci_sci
North is NOT up. It is 31.2° counterclockwise from up.
I have updated this to remove Gomez’s Hamburger, which is not a planetary nebula but rather a protoplanetary disk. The picturesque Hen 2-437 has taken its place. See previous version of the collage, now renamed “99 Planetary Nebulas” (I could put “And a Protoplanetary Disk” as a subtitle, hehe!) here. If you would like to download larger sizes, including a 10000 pixel wide lossless PNG, click here. Larger versions are always available for download at my Flickr gallery.
Also, Flickr seems to be allowing me to upload the 10000 pixel wide version now. The previous one was uploaded at half that size. It was bugging out or something last time I tried.
Here is a copy of the original description for your convenience, since it still applies:
Inspired by insect illustration posters, this is a large collage of planetary nebulas I put together bit by bit as I processed them. All are presented north up and at apparent size relative to one another—I did not rotate or resize them in order to satisfy compositional aesthetics (if you spot any errors, let me know). Colors are aesthetic choices, especially since most planetary nebulas are imaged with narrowband filters.
How many of them can you identify?