Date:  2024-04-27

Discovery:  Randy carried out some OIII narrowband sky surveys in a low galactic latitude region in Gemini from December 2023 through early-February 2024.  One of those survey fields, after 18 hours of integration time, revealed the first faint OIII signature from this object.  There were no references to a nebulous object at this location in official data sources (HASH and SIMBAD).  Juan and Randy joined forces with their respective imaging rigs and set out to acquire data for a deep integration of this faint object before the imaging window closed in early May.

Data:  With two rigs, we were able to successfully capture enough data to reveal many details of this object, which we believe has never before been imaged.  We captured most of the data through H-alpha and OIII narrowband filters.  Starless mono masters of the emission nebula were created from the narrowband data.  H-alpha was assigned to red and OIII to blue for colorization.  The green channel is a mix of H-alpha and OIII.  Broadband RGB stars were blended into the colorized image in place of the narrowband stars.  Our data collection period was from December 2023 to April 2024.  Our total integration time was 60 hours for H-alpha data, 62 hours for OIII data and 3 hours for RGB broadband stars.  North is up and east is to the left.  Our monochrome images and negatives for the H-alpha and OIII channels are shown in the "Revisions" section.

Equipment:

• Juan used a Sky-Watcher Esprit 100ED with ZWO ASI2600MM camera located under SQM 21.6 skies at Trevinca Skies Telescope Hosting at A Veiga, Spain.
• Randy used a Takahashi FSQ106EDX4 with ZWO ASI2600MM located under Bortle 4 skies in an amateur observatory at Hamilton, Virginia, USA.

Object Morphology:  As we processed early versions of the data, the object gave us the vague impression of having a bipolar morphology with a bright east lobe and a much fainter west lobe.  The brighter east lobe was easy to see from the early stages of integration.  It is oriented as if one were looking into the large end of a funnel.  Bright H-alpha signal defines the outside of the east funnel.  The interior is filled with strong OIII signal.  We could faintly imagine another opposing funnel facing away from us.   The west lobe was much dimmer and lacked a clear form, even to the end of data collection.   Sandwiched between the lobes, there appeared to be a “flat skirt” of H-alpha nebulosity ejected perpendicular to the lengthwise dimension of the opposing funnels.  As we integrated the last of the data into the image, the anticipated west funnel structure did not distinguish itself strongly, if at all, from the background and surrounding interstellar nebulosity.  Based on the final image and central star position/trajectory (described below), our more defensible interpretation of the object morphology is one consisting of a single mature and evolved elliptical structure with interaction between the elliptical shell and the ionized interstellar medium on the west side of the elliptical structure.

Local Field:  A wider view of the field around the object shows that it generally lacks any other significant emission or reflection nebulosity other than the thinly-spread interstellar matter.


Possible Central star:  According to the 2021 Catalog of White Dwarfs (Gentile+), one white dwarf exists in a 10 arc minute radius around the geometric center of the main shell.   This WD is at a superposition that could put it inside the emission shell.  Its coordinates are 6 50 01.73 +34 26 53.80.  Its galactic latitude is +14.68. There is no GALEX coverage of this region.  Neither the Gaia DR3 catalog nor the 2021 WD catalog has any temperature for this WD.  


A likely reason for the CSPN to be offset to the east of the optical center of the shell is simply that the object is an older, evolved PN.  The gathering of the OIII near the possible CSPN is typical of many PNe that we are familiar with.

The WD has a proper motion aspect in the lateral/vertical directions that would lend strong support to the above explanation of its current offset position.  The proper motion statistics from Gaia were used to plot the past 2D positions of the WD at 10,000-year intervals and are shown in the image below.  The vector of past proper motion can place the WD in a more viable superposition that is closer to the shell's optical center and that could explain the evolved shell's present footprint.  This methodology also could provide a measuring stick for determining the approximate age of the shell.


Alternative Theories:  We don’t yet want to give up on the bipolar PN possibility.  It is not out of the question that our orientation to the object could be nearly pole-on and that a further-away lobe is partially obscured — preventing us from seeing it for what it is.  It is also possible that the proper motion statistics for the candidate central star are slightly inaccurate.  The vector of past proper motion, adjusted just a few degrees clockwise, could put the WD in a viable location in the past to support the current footprint of a possible bipolar form.

Next Steps:  We submitted our images and comments to planetarynebulae.net for their feedback.