IC10 is a dwarf galaxy undergoing a lot of star formation. These are always interesting to look at because of the glowing gas clouds commonly associated with such activity. The nebulas in my picture this time are two different colors because I only had partial coverage for the narrowband H-alpha filter. So the places where the fluffy clouds are red were included, but the places where they are greenish were excluded. Maybe it was strange of me to do this, but I take what I can get from the archive.
Easily visible within the galaxy are numerous clusters of bright, young, blue stars. Some are surrounded by relatively denser hydrogen gas, while others seem to exist independently from it already, forming sparkling open clusters. A number of older, more densely packed balls of stars called globular clusters are also readily apparent, with individual stars easily resolved within each. Another thing that makes this image beautiful are the few Milky Way stars populating the foreground. These are easy to spot because they are apparently brighter and larger, and often form noticeably cross-shaped diffraction spikes.
Of note during processing, those foreground stars sure did make life difficult for me. Nearly every one of them had charge bleeds that had to be cleaned off. The chip gaps were variously missing one channel or two. I worked with what I had to avoid cloning data, but in places where only F435W was available, I did create some noise texture to assist with blending and avoid visual distraction. This is easily noticeable at close inspection, but harder to detect in the broader image. This is something I do intentionally so that interested observers can make the distinction between areas of complete and incomplete data while maintaining and aesthetically pleasing image. There is also a small bit of missing data in the lower left corner I did not crop off because I did not want the aspect ratio to be so wide.
Data from the following proposals was used:
Intermediate Mass Stars and Unusual Stellar Mass Limits in a Starburst Galaxy
A Chandra and HST Study of IC 10: The Nearest Starburst Galaxy to the Milky Way
Red: ACS/WFC F814W + WFPC2 F656N
Green: ACS/WFC F606W
Blue: ACS/WFC F435W
North is NOT up. It is 59.8° clockwise from up.
Tags: starburst dwarf galaxy HST H-alpha near infrared red blue ACS/WFC WFPC2 F814W F606W F435W nebula 6406 9683
Left side: Titan in natural colors with wideband Red, Green, Blue, and UV filters in their respective channels with Blue and UV sharing the blue channel.
Right side: Using narrowband data to peek through Titan's haze. Red is infrared and green and blue are two methane bands (MT1 and MT2, respectively). I also applied the infrared data as luminosity to further enhance the visibility of Titan's surface features.
Compositional inspiration for side-by-side views came from Val Klavans's wonderful work.
These data were acquired by Cassini on 2013 January 05.
Left
Red: RED 650W
Green: GRN 568W
Blue: BL1 451W + UV3 338W
Right
Red: CB3 938N
Green: MT2 727N
Blue: MT1 619N
START_TIME >= 2013-01-05 04:17:54.0
START_TIME <= 2013-01-05 04:27:28.0
Instrument = ISS
Tags: Titan Saturn Cassini Haze Atmosphere Surface Clouds PDS Planetary Image Atlas polar vortex
It's easy to see why this bipolar nebula is called the Retina Nebula. It is one of the most detailed in the archive. Because it's so close, fine details which might otherwise be lost are visible.
The reticulated pattern of dust, which appears to form a toroidal shape around the star puzzles me since it is not quite like anything else. There are dust structures in other bipolar nebulas, just not quite like this. They remind me of NGC 7027 but with finer structure and not in the form of dual rings. The NGC 7027 image has the advantage of near infrared data from NICMOS, which makes it much easier to see its dust structures. Knowing that makes me wonder what an Infrared image might reveal in IC 4406.
Also visible is a faint arc above the core which is also present below but less well defined. I didn't notice it in many other images of this nebula because it's so faint and easily lost to the background.
Both pc and wf data was combined from two different years (2001 & 2002).
Red: f658n
Green: f656n
Blue: f502n
North is up.
Tags: planetary nebula IC4406 IC 4406 retina nebula HLA Hubble
STIS is Hubble's spectrograph. It usually doesn't make images*. Sometimes, though, it does, and I feel lucky when I find them, because they can really be quite good. The colors are cobbled together from a variety of sources other than STIS. Some from WFPC2, others from WFC3. Color data wasn't available for the whole frame, so the top corners are monochrome. Still looks pretty good. Even got some H-alpha data in there.
There is a lot of dust in this nucleus, and apparently a lot of star formation going on. We can easily see the pink fluffs of clouds which are associated with the processes of star formation.
*Phil Plait tells me it makes a lot of images. I must be missing something when browsing the archive. I will try to be more watchful in the future.
Data from the following proposals were utilized:
archive.stsci.edu/proposal_search.php?mission=hst&id=...
archive.stsci.edu/proposal_search.php?mission=hst&id=...
archive.stsci.edu/proposal_search.php?mission=hst&id=...
Color channels are generally:
Red: F814W and F658N
Green: F675W
Blue: F555W
Luminosity: Broadband optical light from STIS
North is 140.3° clockwise from up.
Tags: STIS Hubble galaxy nucleus spiral dust halpha
This is a followup to Proxima. This time, I am not pretending to know French or be cultured.
I would like to thank Nitpicker for helping me muddle through calculating the necessary mirror size. That's not his real name of course but he'll know who he is if he ever reads this.
To create the fake image of a star on the right I took a real Hubble exposure of Neptune and simply brightened the planet's disc to a flat white.
"A single Hubble PC1 pixel is 0.046” wide and Proxima Centauri has been measured to about 0.001” in diameter. Proxima Centauri is therefore only 2% of the width of a single pixel in the image to the left. Hubble’s mirror would have to be over a kilometer wide to achieve this resolution."
Tags: Proxima Centauri angular resolution Hubble HST HLA star PSF point spread function
