STROTTNER-DRECHSLER 127 / THE BLUE ICE CUBE NEBULA

Behind each new discovery by the German-French team of Xavier Strottner and Marcel Drechsler is not only an exciting story, but also an exciting object. The 127th entry in the catalog of new discoveries is a probable planetary nebula with a clearly visible central hot star - a white dwarf. What is special about the central star is that it is a binary system discovered by the transit method. Both orbiting stars are responsible for the fact that StDr 127 does not have the classical bubble-like structure of a planetary nebula, but shows bipolar ejection regions along a northeast-southwest axis. It is unknown what kind of companion of the central star it is - probably a very faint, cool dwarf star, or a second white dwarf.

StDr 127 was discovered on December 25, 2020 by Xavier Strottner and Marcel Drechsler during a search of digitized data from the Digitized Sky Survey (DSS), which contains data taken by the Palomar and UK Schmidt telescopes. The candidate was accepted by Pascal le Dû, registered and added to the StDr catalog. Shortly thereafter, StDr 127 was also added to the international HASH database of galactic planetary nebulae.  Since no official spectrum of the candidate has been produced yet, StDr 127 is still considered a PN candidate, even though its appearance leaves no doubt that it is a true planetary nebula.


Constellation: Centaurus
Catalogue designation: StDr 127, PNG 298.2+18.2
Coordinates: 12:26:32.07  -44:21:11.61 (J2000)
Apparent Size ~ 37” x 45”
Type of object: Probable planetary nebula (spectrum still pending)
Distance: approx. 9700 ly (+/- 3500ly)


structure of StDr 127


GATHERING THE DATA
JOHN HAYES: Early this year (2022), I offered some of my telescope time in Chile to help Marcel and Xavier with their search for new objects in the Southern Hemisphere.  Right away, Marcel responded with the coordinates for a potential candidate that was relatively high in the southern sky.  Eager to try it out, I set up the scope to stare at this region to see what I could find.  After stacking 6.8 hours of Ha data, I couldn’t see a thing!  So, I sent the stacked data off to Marcel and he spotted something in the image right away.  I had to defocus my eyes, clear my mind, hyper load on vitamin-A, and isolate in a dark room before I could see what he spotted.  It was extremely faint!  Either way, we agreed that getting a useable image of that object was going to be very difficult/impossible—at least with my equipment in a reasonable amount of time.  Marcel and his team make finding new objects look easy but behind the scenes, it’s not always as easy as it looks!  Sometimes, it’s a bust and that a part of the game.  So, it was time to pick up the pieces and go looking for something else.

By then, we had used up a lot of the stable, clear summer weather in Chile and the conditions were becoming unstable.  Marcel suggested another potential target and right away, I could see that this one held a lot more promise!  It was bright and it was small.  At an apparent size of only 37” x 45”, I could see right away that it would take good seeing to bring out much detail and unfortunately, the weather just would not cooperate.  I started imaging in early May and ended about two months later in early July and during that entire period, the weather was very unsettled. This was just before around 10” of snow fell in early July and we had weeks of cloudy weather.  I gathered a lot of data with FWHM in the range of 3” – 4” and by filtering out the best subs, I was finally able to assemble a collection of subs with an average of a bit over 2” FWHM.  I focused most of the effort on gathering Ha, OIII, and SII narrowband data with only 50 frames using each of the RGB filters.  The average yield across the channels was around 30% using a threshold set at 2.5”.  I calibrated and aligned all of the channels and my initial, quick look at the data revealed a mostly deep blue, nearly rectangular object that I initially dubbed the “Blue Ice Cube”.  Marcel took that collection of masters for each channel and produced the final image that you see here.

Acquistion Dates: 5/10/22 – 7/08/22
Data: R – 30 x 600s / G – 13 x 600s / B – 13 x 600s / Ha – 78 x 600s / OIII – 80 x 600s / SII – 52 x 600s

PROCESSING THE DATA
Marcel Drechsler: As expected from an excellent astrophotographer like John Hayes, John provided us with superb data.  The biggest difficulty was to accurately bring out the fine structures that characterize this object and not inadvertently enhance artifacts, but only real structures. To make the fine and extremely faint halo visible, various techniques were used without affecting the bright core of the nebula. Methods for denoising were used only purposefully and extremely sparingly in order not to destroy any structures.

CONCLUDING WORDS
Marcel Drechsler und Xavier Strottner: Since we discovered StDr 127 at the end of 2020, we were aiming to take a photo of this exciting object. However, since StDr 127 is located in the southern hemisphere, this severely limited our possibilities. Our joy and surprise was immense when John Hayes contacted us in early 2022 and offered to assist us in taking photos with his setup in Chile. It quickly became clear that StDr 127 would be the first real target of our hopefully long and productive collaboration. Our expectations were exceeded - not only in terms of the data, but also in working with such a professional and friendly astrophotographer! We thank John beyond measure for his commitment and trust in our team.