Well-known for its similarity to the Milky Way, looking at NGC 6744 is kind of like looking into a cosmic mirror. We will almost certainly never know what our own galaxy looks like from afar, but we can look across the void and try to find something very similar.
Just like we see here, The Milky Way is known to have a central bar full of older, yellower stars, and a bulge. Some say the bulge is peanut-shaped, but I am sure it's more of an X, though I can see how it could also be described as a peanut. I have noted the X feature in the cores of a few other galaxies, and while it seems to be a fairly common morphology, I think it's only visible when viewed edge-on, so we can't see it here.
Moving out from the core, dusty lanes and pink nebulas of star-formation are also evident. When given a wider field of view, two arms a little more than vaguely defined can be seen. Numerous spurs and disconnects give it a halfway chaotic or fluffy, flocculent appearance.
I was gathering a few resources and references here and there to attempt an illustration of the Milky Way and Andromeda paired together from some distant vantage point when I discovered this galaxy was indeed in the Hubble archive. Not only that, but it's got a fantastic set of filters to work with and is part of the wonderful Legacy ExtraGalactic UV Survey (LEGUS) which is chock full of intimate views of a variety of galaxies.
This image is possible thanks to the following two proposals:
LEGUS: Legacy ExtraGalactic UV Survey - HST Proposal 13364
H-alpha LEGUS: Unveiling the Interplay Between Stars, Star Clusters, and Ionized Gas - HST Proposal 13773
Note: Data for this image can be downloaded from the HLA, but the processing is better if you download it from this page: archive.stsci.edu/prepds/legus/dataproducts-public.html
The F657N data is not on the LEGUS page and must be obtained from the HLA as of this writing. 2017/07/14 Additional note - get the drc file from DADS instead of the drz. It won't open with FITS Liberator, but you can open it with SAOImage DS9, resave it, and then use Liberator.
Red: WFC3/UVIS F657N + WFC3/UVIS F814W
Green: WFC3/UVIS F555W
Blue: WFC3/UVIS F275W + WFC3/UVIS F336W + WFC3/UVIS F438W
North is 148.8° clockwise from up.
Tags: Hubble HST Spiral Galaxy dust LEGUS H-alpha ultraviolet near infrared visible 13364 13773
Long have I gazed upon and admired one of the greatest images Hubble has ever taken. It's impossible not to pause and take it all in, even after all these years and all the times I've seen it. Ten years ago this was observed for Hubble's 20th anniversary. We're now approaching the telescope's 30th anniversary, which is guaranteed to be spectacular. Please do look at the original anniversary release to understand the history of this image: hubblesite.org/contents/news-releases/2010/news-2010-13.html
One of the ways I learn to appreciate HST imagery even further is by processing it myself. There's nothing quite like staring at every little detail up close and personal to feel intimately acquainted with some data. I went into this thinking there wouldn't be much different that I could do that others haven't already done... and I was wrong, which was nice.
I learned something new recently that involves subtracting light out of imagery to reveal details that are otherwise lost in a kind of bright glare. It works very well with elliptical galaxies that are very regular in shape and easy to create simple, smooth models of. The idea was still fresh on my mind when I realized that the [O III] data seemed to match up with a bright gaseous fog permeating the landscape around the Mystic Mountain. I tried applying the same technique, and to my great surprise, it worked, and really well at that. The Mountain was deeply revealed in such a way that it became more of a Pillar. Yes, it was always a pillar, but it was hard to see.
There are a few places where subtraction was obviously imperfect (at least, obvious if you flip back and forth between the two) but it doesn't detract from the overall view. I also had to mask off the PSFs (point spread functions) of the stars since subtracting them out doesn't do any good.
Anyway, hope you enjoy it. As always, it's a privilege to get to work with these amazing data.
Data from the following proposal were used to create this image:
20th Anniversary of HST Launch
Note that mosaics are already composed and ready for anyone to download and try for themselves: archive.stsci.edu/prepds/carina/wfc3/
One more note: Subtraction was not linear and applied with varying weight to each filter. It's part science, yeah, but it's also art. This means eyeballing it and adjusting it until it looks "right" to me.
Lavender screen: WFC3/UVIS F502N (I used this to put some of the subtle color variation back into the image after subtraction)
Red: WFC3/UVIS F673N-F502N
Blue: WFC3/UVIS F657N-F502N
North is down.
Tags: HST Hubble Carina nebula mystic mountain gas dust star formation Herbig-Haro jets anniversary pillar subtraction processing narrowband [O III] HH 901 HH 902 HH 901 902
A supernova explosion that happened in Centaurus A. This animation represents about 1.5 years of time, omitting the first frame which is a legacy image from 2010. This all happened a bit more than one month after the initial explosion. What you see here is the fading of the supernova, and then the blueish ring that is a light echo that began to propagate outwards immediately after the initial explosion. Upon closer inspection, a second, fainter light echo seems to appear following the first in the last two frames.
Some processing notes: The telescope never oriented the same way twice when taking observations, resulting in diffraction spikes and the whole PSF of the foreground star being incredibly distracting. I stabilized this quite a bit by both using a stacked median version of the datasets to remove the spikes completely, and then added the 2010 spikes back on to all the frames. Red channel data were missing from the 3rd and 4th frames (second and third brightest images of the fading supernova) so color for that is both guessed and pulled from the 2010 data. I did use a fair amount of clarity and texture filtering from Camera Raw.
Data from the following proposals were used to create this image:
Star Formation in Nearby Galaxies
Light Echoes and the Progenitor of SN 2016adj in Cen A
Light Echoes and the Environments of SNe 2014J and 2016adj
Red: WFC3/UVIS F814W
Green: WFC3/UVIS F547M
Blue: WFC3/UVIS F438W
North is up.
Tags: HST Hubble supernova explosion light echo SN2016ADJ SN 2016ADJ visible dust galaxy Cen A Centaurus A
Wasn't sure how this would turn out when I downloaded the data. I wanted to do something a bit different from other Orion images, so I chose what I would consider a rather challenging set of filters from a large mosaic. The blue color represents Paschen β continuum, which is hydrogen α's near-infrared cousin. The reddish color represents the H2O/CH4 line, which is important to help separate out what astronomers were looking for in this dataset—brown dwarfs in this case.
There are a lot of cool details to see that otherwise would be obscured in this near-infrared view. The mountain-like formation south of the Trapezium stands out way better than a visible light image, and I enjoy the way the layers of gas appear like a gossamer fabric. There are even a few background galaxies visible.
If you looked at this image without saturation adjustments, you'd barely see any color at all. The filters are barely separated, and it shows in the combined image. So I had to increase saturation a lot. I was inspired by Bill's color STIS image I did a little while ago for this. I wanted to take something that had almost no color, and see if I could get some beautiful colors out of it. In addition to the saturation boost, I set both clarity and texture sliders in Adobe Camera Raw all the way to 100 with stars masked. These really help bring out all the wispy details without adding too many artifacts.
So... I spent a *lot* of time cleaning up cosmic rays on this one. Please do download the original size, zoom in, etc.
Right now this is only a two-color image. I might come back later and add a third filter. I kind of like the simplicity of this, though.
Some portions of the image contain J band data from CTIO Blanco's ISPI instrument. Notably, the upper left corner, and portions around the outer edges. I cloned some HST stars and put them in place of the CTIO stars so the whole image looks more cohesive. Color in those areas is approximated. CTIO/ISPI data can be found here: archive.stsci.edu/pub/hlsp/orion/images/ispi/
Data from the following proposal were used to create this image: The Orion Nebula Cluster as a Paradigm of Star Formation
Red-Orange: WFC3/IR F139M (H2O/CH4)
Blue-Cyan: WFC3/IR F130N (Paschen beta continuum)
North is 9.3° clockwise from up.
Tags: mosaic Orion Hubble HST narrowband near-infrared 13826 Prop13826 nebula star formation emission dust foggy proplyd Trapezium gas Paschen β Paschen beta infrared
Another supernova remnant from the Large Magellanic Cloud, seen by Hubble and Chandra in visible, near-infrared, and x-ray light. This time I've overlapped two color images together, because I heard you like color so I put color in your color so you can look at color while you look at color.
Hubble data from the following proposal was used to create the image:
A Search for Surviving Companions of Type Ia Supernovae in the Large Magellanic Cloud
Red: .30-.70 keV
Green: .70-.80 keV
Blue: .80-4.20 keV
(Obs IDs 3876 & 4440)
Red Screen & 30% Luminosity: WFC3/UVIS F656N
Red: WFC3/UVIS F814W
Green: WFC3/UVIS F555W
Blue: WFC3/UVIS F475W
North is 48.38° clockwise from up.
Tags: Hubble HST Chandra CXO x-rays x-ray visible near-infrared SNR supernova remnant nebula emission bubble DEM L 71