There is a new paper out called a Recurrent Nova Super-Remnant in the Andromeda Galaxy which is about M31N 2008-12a. You can find the article at this LINK. The article summarizes more of what astronomers have discovered about M31n 2008-12a or 12a as they are calling it. I'll follow suit here. The paper introduces the notion based on observations from the Liverpool Telescope at La Palma and the Hubble Space Telescope of the system. 12a as it is called in the paper, is now shown to be surrounded by a nova super-remnant that is at least 134 parsecs by 90 parsecs, which is larger than all known remnants of supernova explosions we have documented. The Veil Nebula in Cygnus, is about 110 light years in length and 50 light years across. 12a is 436.84 light years in length, and 293.40 light years across. You can see how much more massive the nova super remnant is when compared to the Veil Nebula complex.
To put this into astronomical terms, 1 parsec is equal to about 3.26 light years or 31 trillion kilometers or 19 trillion miles in length. The 134 parces is about the distance from our Sun to the Messier 45, the Pleiades. Look up this winter at M45 and think that is how long the super remnant of 12a is in length! These images from the paper will show that the super remnant is elliptical in shape and brighter on the southwest than on the northeast edge.
Taken by the Liverpool Telescope, The Hubble Space Telescope
Here you can see the location of 12a in the first two images going left to right, and in the first or green image, the blue sources are field stars. The view of the elliptical and closed ring nebula is seen within that white dashed ellipse. The midbdle image is from the HST and is of the same region though all stellar sources have been removed. Here you can clearly see that the nebulosity is not smooth, but that there are filaments and knots interwoven here. It is quite similar to the image below of the Galactic recurrent nova T Pyxidis. The red squares discuss the two regions discussed in the paper linked above. The third image on the far right, in black and white is from the Hubble Space Telescope and is a zoomed in image showing the region withing the large red box in the center image. Here the filaments, knots and viewable separated by 12pc and 5pc.
To highlight the paper, and I am sure to massacre it, but the paper covers 7 major points about M31N 2008-12a. First is that this recurring nova erupts about every 347 +/- 10 days though there is the possibility that there is a frequency of 174 +/- 10 days. The reason for the second figure is that it is quite possible when this event occurs when M31N 2008-12a is near the Sun in March or so and that we cannot observe it as a result.
Second, it is the "fastest optical evolution and the highest ejection velocities, the hottest X-ray source, and the most rapid recurrence cycle of any known thermonuclear nova." When you add these together it equals the most massive white dwarf ever discovered. That covers three through six. The seventh and last point is that based on ground based imaging the images show a ring like structure that is spatially coincident with the nova. This is see above in the images. As the images show, especially in the high spatial resolution from the HST, the out shell is not smooth, but fragmented into filaments and knots as mentioned above.
A spectrum taken of the super-remnant shell shows that here are no bands or findings of neon in the super remnant nova and that may indicate that the white dwarf, that is approaching the Chandrasekhar limit of 1.4 solar masses, is likely composed of carbon and oxygen, indicating that in 20,000 to 40,000 years the white dwarf is likely to go off as a Type Ia Supernova, though we may find that there is a Neon-Oxygen core and that the white dwarf may collapse into a neutron star directly.
The paper then discusses how they developed a model to run to show how the nova super-remnant developed. Actual observations of this nova has occurred over the last decade, but the model shows that M31N 2008-12a super-remnant has been erupting for well over a million years. That is the only way the nova super-remnant could have obtain so much mass and size was for eruptions occurring over a million years.
The model shows that the super-remnant contains three distinct regions. The inner cavity where the recent ejecta effectively undergo free, high velocity expansion while cooling." Next the ejecta pile up where the ejecta from previous eruptions collide, then slow by interaction with the Interstellar Medium or ISM. The third is super-remnant shell, "which consists almost entirely of swept-up ISM that is slowly driven outward by the multiple-ejecta pile up, occurring in its inner edge."
A few other takeaways from the paper. The binary pair is most likely a red giant and it is accreting most of its mass onto the white dwarf via a wind that transfers the mass. Some mass transfer may be occurring via an accretion disk, but most is being transferred via the wind. That is the other finding, that the binary companion is indeed a red giant.
To summarize, the paper reveals that there is an extremely large super-remnant nova around M31N 2008-12a, a white dwarf that is accreting mass from a red giant companion. The red giant is transferring its mass via a wind, and perhaps some mass in an accretion disk. Also the super-remnant nova is massive in size, is made of 3 components where material ejected is speeding out, then impacting with previous ejecta to create the other the super-remnant nova. The nova is not smooth but is comprised of knots and filaments. If M31N 2008-12a ends it cycle as a Type Ia Supernova, then the super-remnant will be destroyed from the resulting supernova. If 12a ends up as a neutron star, the remnant will eventually over time dissipate and blend into the ISM.
This is going to be a long entry in some ways. I went observing Monday night and have over 20 sketches with 35-40 objects sketched in them. So with those I need to take my camera and a photo of each, then bring the image into my file and then upload. So that is a couple of days out. This post will be about my journey of eyepiece and what eyepieces are available.
My first telescope was an Orion XT8. Not a perfect telescope, poor azmuith motions, decent altitude motions, and I had a Telrad and a 9x50 RACI finderscope on it. I loved that scope as it was easy to transport, easy to use and I did my Messier's with that scope. The scope came with two eyepieces back in the day. The first was the 10mm Sirius Plossl:
The 10mm was an okay eyepiece, IF you like tight eye relief and have to put your eyeball right down next to that tiny circle. It did do okay on Jupiter and planets though.
The XT8 also came with the 25mm Sirius Plossl by Orion. This eyepiece was wonderful with plenty of eye relief and good views. This led me to locally purchase from a shop that carried the Orion Sirius Plossls the 32mm, the 17mm and the 12.5mm. The 32mm is the best of the bunch in terms of eye relief, placement and sharpness in the view. I still have this eyepiece though the rest are long sold off.
Here are the measurements based on a 10" f/4.7 Orion XT10 dob which was my next step up.
So this has the eyepiece, the type, size in mm, the scope size in mirror and focal ratio, the magnification x, and true field of view with the exit pupil. The larger the true field of view and exit pupil, generally the better the view.
My next eyepiece was a 9mm Orion Expanse Eyepiece. This eyepiece had blackouts for me, while kidney beaning depending on where I placed my eye, but the 66 degree Field of View was a wonderful increase from the Orion Sirius Plossls. It had 1.25 barrel size, 16mm eye relief (if you observe with glasses you want 20mm of eye relief or more though you may squeeze by with 18mm to 20mm of eye relief). As I shared it had a 66 degree field of view. I really, REALLY liked this eyepiece, and liked it until I gave it away to a student who had gone through a program to get an Orion XT6 and wanted a wider field of view with higher magnification. Agena Astro has a version that is cheaper than Orion's version with all the same elements, design and stats. It can be found here. At Agena they go for $40 to $45, not bad if you don't mind the kidney beaning.
From here I moved into the Orion Stratus line of Eyepieces. I picked the Stratus eyepieces over the Hyperion which are both clones of the LVW eyepieces because I could purchase the Stratus eyepieces locally here for cash, with no shipping.
Here you can see the entire line and at one point, I owned that line. I began with the 21mm and the 13mm as I felt those provided the best views based on reviews and the 10 inch dob I was using at the time. The 21mm was my finder eyepiece or wide field and the 13mm allowed me to get in a little closer. I next added the 17mm and the 8mm which served me well. I could and probably should have stopped there but I went forward and purchased the 5mm and the 3.5mm. I used the 5mm a lot more than the 3.5mm.
The Stratus line served me well as I grew into the hobby, and I am sure the Hyperions would have been just as well. The Stratus line for me taught me what coma was, as I viewed coma in them in my 10 inch 4.7 inch dob. On the 13mm, 17mm and 21mm I would see coma on the outer 15% of the view, about 10% on the 13mm. Stars were bright and tight, though as the moon during lunar observing would fringe on the edge of the longer focal lengths. For the cost, just over a $100 they were not a bad set of eyepieces and they got me observing for several years with them, while I learned the ropes. I major improvement over the Orion Sirius Plossls and the Expanse line. Decent performers but I wasn't content and kept looking.
One evening I had set up my 14" Orion XX14i out at Lakeside, Utah when a fellow club member, Steve Fisher, a most gracious and wonderful person and man, loaned me his Pentax XW's to try out. All I could say was WOW! They blew away my Stratus line and there was no doubt to their quality or that they were a premium set of eyepieces. I knew then I had to have them. They were expensive and as my wife keeps good control on our finances so we can achieve our goals (I am all for that as I tend to spend or can when enabled) I purchased one or two each month as they fit in the budget. I started with what I consider to be probably the best eyepiece I own, the 10mm Pentax XW. Clear to the edge with no aberrations showing, I have seen more using this eyepiece than any other. Contrast is tremendous as are the details it brings out. I then added the two extremely solid eyepieces the 14mm and 20mm and when added to a Paracorr they equal the others. The 14mm and 20mm without the Paracorr will show some field curvature but not enough that I was ever concerned. Next came the 7mm, the 5mm and the 3.5mm. The 30mm and 40mm were out of production and I have had to add them to the line from the used market.
I have to say that the Pentax XW line was my first premium set of eyepieces, and I love them, and openly have a bias to them. My bias I'll admit here, came because one night, out in Utah's West Desert, Steve Fisher trusted me to use his Pentax XW's and they changed the way I observe, the way I sketch, they made me want to improve in the hobby as an observer and in every way. Thanks Steve, not sure if you will read this, but I really do appreciate the gesture and remember it all these years later. I use the Pentax XW's everytime I observe, and they are incredible. The 10mm, 7mm, 5mm and 3.5mm need no Paracorr, though I still use one on them. Too lazy to take it out. All but the 30mm and 40mm are 1 1/4 inch barrells with 70 degrees Field of View. I usually don't loan mine out though, unlike Steve.
Next came a few longer focal lengths for wide field. My first wide field eyepiece was a gift from my daughter. She was in high school and working and the cost of a TeleVue Panoptic 27mm was not something she could just go purchase. She saved up for 6 months to get that for me. I still use the 27mm Panoptic in the field as the weight is great for balance and for me the views are sharp and clear. Some who use this eyepiece say when they scan they get distortions, I have never seen that.
TeleVue 27mm Panoptic: Eye Relief: 16mm; Field of View: 68 degrees; Barrel Size: 2 inches; Weight 1.1 lbs. A quiet sleeper in the Panoptic line and a great alternate for the 35mm Panoptic if the low power and size and weight of the 35mm Panoptic is too much for you.
At this point in my personal eyepiece journey I should have been content with the full Pentax XW line and the 27mm Panoptic. Then I bought in to the kool-aid so to speak. Explore Scientific had come out with several lines and since I really enjoy the 70 degree view, I decided to purchase and compare the 20mm 68 degree and 24mm 68 degree by Explore Scientific. I have to admit upfront that the overall quality in the 20mm 68 degree by ES (Explore Scientific) puts it in the same class as the Pentax XW. I believe the light transmission, contrast and color reproduction is the same as the shorter focal length XW's if used with a Paracorr. The 20mm Explore Scientific's 68 degree eyepiece's only negative to me is the 15.3mm of eye relief. If you wear eye glasses to observe it is just a tad short. If not, the 20mm ES 68 degree for the cost is outstanding. I still own mine though it is seeing less and less time in my personal focuser.
The Explore Scientific 24mm 68 degree I believe is a very good solid eyepiece. Equal to the Panoptic 24mm at the center of the field, while dropping off slightly on the edge performance. It is a great eyepiece to pan the Milky Way or night sky with it. Eye relief at 18.4mm is good for glass wearers with a weight of 11.6oz and a 1 1/4" barrel.
I want to point out again, that here I drank even more eyepiece kool-aid and decided to take a step in the the 82 degree line of eyepieces that Explore Scientific offers. My first purchase in this line was the famed 30mm 82 degree eyepiece.
The ES 30mm 82 degree eyepiece is a stunning winner. With 22mm eye relief, an eye glass wearer can easily use this wonderful and immersive eyepiece. Views have always been sharp and being able to fit the whole part of the Witches Broom/Veil Nebula into the field of view generates a long lasting and enduring memory. It is not an eyepiece that I use on a regular basis, but I do use it and it stays in my eyepiece case. I have compared it to the TeleVue Nagler 31mm and the nod does indeed go to the 31mm Nagler, but the 30mm Explore Scientific is a very, very close second. This was one purchase where I was glad that I drank the eyepiece kool-aid on. Works great with either a good OIII or Narrowband filter
My next eyepiece kool-aid was the 24mm 82 degree Explore Scientific eyepiece. It is large, very large and at 82 degrees gives a wonderfully wide field. The eye relief at 17.5mm is good, and solid for those wearing eyeglasses but I have had a couple of times of having to adjust where to put my eye on the eyepiece. I've kept it, I don't use it hardly at all now and probably need to consider not keeping it except for maybe for use at an outreach event. This is an example of a purchase where I learned about the eyepiece, but I didn't need that experience or paying out the cash for that experience.
Now I wanted to compare the 4.7mm and 11mm Explore Scientific 82 degree eyepieces to my Pentax XW line. Well, for me, the 4.7mm at 13.6mm eye relief was too short and I felt I had to bury my eye into the eye cup in order to take in the view. This eyepiece was no wear near the performance of my Pentax XW 5mm and it lasted in my case all of a month before I sold it on the used market.
The 11mm 82 degree Explore Scientific is a decent eyepiece. The eye relief at 15.6mm is good, and I didn't have a problem with this eyepiece but in the areas that matter to me, it just is no wear near the the Pentax XW 10mm. However, unlike the 4.7mm which I sold quickly, I have kept this one and use it when I do outreach or when teacher younger observers how to observe.
Both the 4.7mm and the 11mm Explore Scientific eyepieces are examples of purchases not needed. Again, I paid for the experience, made my money basically back on the 4.7mm but the 11mm I only use about 4 to 6 times a year, and personally, I don't use that eyepiece myself.
From here I decided after using my friend's Jeff Ethos, and my other friend's Matt Ethos and 100 degree ES eyepieces, to try out the Explore Scientific 100 degree eyepieces.
I first purchased the 9mm 100 degree by ES. I used it in the field and found that there were parts of the experience I liked, many more that I didn't. I had to hold my eyeball sideways to take in all the field, or pan the eyepiece FOV to see everything that was there. I had also, to stick my eyeball almost directly on the glass in order to take in the view. The same occurred on the 14mm and somewhat on the 20mm. I found overall, I REALLY wanted to like and use these eyepieces but I just never could bring myself to like the eyepieces, their eye placement and presentation. I loved the center of the view but after about 6 months of really trying these out, I found that the 100 degree field of view just is not for me. I sold mine to a fellow educator north of where I lived and got some cash back.
Unlike the previous eyepieces I had purchased which were either redundant or not needed as I had found a superior eyepiece already, I don't regret purchasing these eyepieces. They taught me that the 70 to 76 degree range for Field of View is what I like, what I enjoy and that is where I am settled as an observer. I can easily see though why some people purchase these three or the 21mm Ethos, the 13mm Ethos and a higher magnification Ethos and call it good for the eyepieces they have. I'll state I love the 21mm Ethos, and find it immersive and wonderful views, but that 100 degree FOV is just too much for me.
I think you might enjoy this FOV by Explore Scientific that shows what each of their FOV deliver on an object, in this case Messier 42 (I believe).
I can hear it now; "So Jay, was your eyepiece journey complete?" My answer would follow any amateur bitten by the eyepiece kool-aid bug. "Nope." About this time TeleVue came out to their answer to the Pentax XW, the Delos line. Hyped up big and in some cases, veteran amateur's declared these the ultimate eyepieces. Okay, I thought, my bias rose back up and nothing, and I mean nothing could beat my Pentax XW line. But I wanted to know for myself so I purchased the 17.3, the 12mm, the 10mm, the 6mm in this line. At this time I was hoping to prove that the Delos line was not as good as the Pentax XW line and in truth, as I worked out and through observing and comparing, I found that the Pentax XW line from the 10mm, 7mm, 5mm and 3.5mm were equal to the comparable Delos at similar focal lengths (the 14mm and 20mm Pentax XW were also with a Paracorr). Transmission, color, brightness were all right on. I REALLY liked the Delos A LOT so I kept the 17.3mm, the 14mm, the 12mm, the 10mm, the 6mm and the 3.5mm.
I now hear the question "Why?" That is easy enough. I have multiple scopes and sometimes my son goes observing with me, sometimes a friend goes who doesn't have a larger scope so I loan the Delos out to them, while I observe with my beloved Pentax XW. Now there are times when I want to use the Delos over my Pentax XW, but that depends on the object and the scope I am using. So with this set, this IS a redundant purchase and I in no ways needed it, but I am glad I have it.
This was a totally redundant purchase and one I openly admit I made to compare these to both the Pentax XW's I own and the TeleVue Delos. When the Baader Morpheus came out people claimed, like many do when a new eyepiece line comes out, that these were the best thing since lunch meat was invented. Well, I got two the 12.5mm, the 14mm to compare. My review is here on my blgo and my take away was that without a Paracorr, the Baader Morpheus eyepieces show field curvature on the outer 20% of the edge, worse than the 14mm Pentax XW and with a Parocorr, they clean up nicely but the Delos 14mm and the Pentax XW 14mm with Paracorr out perform the Morpheus. They come close to the premium eyepieces, but there is still a distinct difference between the Morpheus line and the Delos and Pentax XW line. I sold these quickly, lost a little money on the re-sell but it proved something. Different people have different experiences with eyepieces, and that just cause a line of eyepieces are new, they are not the best thing since sliced butter. Reviews after mine seem to agree that the 14mm and the 12mm to a lesser extent have field curvature, coma etc.
The next eyepieces I got into were Ortho's. Why Ortho's I hear. I wanted Ortho's to push some planetary detail and double star detail and to really use and push with deep sky objects like galaxies to see if less glass really is more and provides more detail on fainter objects. My answer to that question was yes based on experience with the Orthos.
Up top you can see the full Baader Ortho line. I passed on the 32mm and the 18mm and went only with the 10mm and the 6mm. These are solid performers with tight eye relief but they do provide wonderful details on the objects I mentioned.
My next set of Ortho's were the University Ortho's. Here I did not get the full set, but focused on the 4mm, 6mm, 7mm and 9mm. I wouldn't consider them premium, but very very good and they do a great job at delivering contrast on deep sky objects that are faint.
I touched on this rivalry earlier, but if you have the Explore Scientific 30mm 82 degree, you don't need to spend money on the 31mm Nagler T5, well unless you have the money and want to. Sometimes I take the 30mm ES out with me, sometimes the Nagler 31mm. Just depends, mainly on which eyepiece case I take into the field. You don't lose with either though the 31mm Nagler is the over winner between the two.
Here is one of my most favorite eyepieces of all time. Enough to where it has semi-retired the 20mm Pentax XW with a Paracorr. The 22mm T4 Nagler is my finder eyepiece, except when I get lazy and don't want to switch between a 2" eyepiece and a 1 1/4" (then I use the Pentax XW 20mm). This eyepiece, the 22mm T4 Nagler gives you a true space walk, and is clear and concise in the entire field of view. It is just beautiful to be quite honest. Glad I got it on sale.
This eyepiece was discontinued by TeleVue, the 26mm T5 Nagler. I actually like it better than the 30mm Explore Scientific 82 degrees and the 31mm T5 Nagler. It isn't quite the FOV but the magnification is a little bigger and the views are tremendous. If I want a finder eyepiece that is larger than the 22mm T4 this is it or if I want an eyepiece that shows an excellent wide field of view. So glad I have this.
I am probably missing some eyepieces, like my Tak Abbe Orthos and two Pentax XO's that of course I just LOVE. Perhaps another day. A few take aways from my experience.
1. Premium or non-Premium will depend on your budget. Don't go into debt for scopes or accessories. Buy as you can and pay cash. If you can afford premium look around at reviews, ask around and then buy one eyepiece and try it out. If you use a dob, try the range of 8mm to 12mm as that is a great viewing range and magnification. If you like that line of eyepieces, then one by one add to them. If you have the cash, then go for it. Premium eyepieces like the Pentax XW's, the TeleVue's will retain most of their value.
2. Decide on a brand, or a type of eyepiece and go for that. Love the Pentax XW's? Buy them. Love the TeleVue Ethos? Get those. Love the Baader Morpheus? Buy them. It is easier to buy in one line than to mix and match since focal lengths and eye relief tend to be similar.
3. Get one range and set and be done. You don't need to have what I have to enjoy a scope at a dark site in the field or in your backyard. Do you observe a lot? Say 6 ore more times a month? Perhaps you want more premium level of eyepieces, perhaps not. Only observer once or twice a month? Non-premium like the Explore Scientific which do come very close or are premium in some models might be your answer. Again, check out reviews, ask and explore.
I have what I have now and have not purchased an eyepiece in over a year. Wahoo!!!!!!! There is nothing I want or need right now or that I see coming up except for a clear sky, a new moon period and a collimated scope ready to go to work!
In November I managed to get out on a Friday night to observe. These were at FR006 Juniper Grove Observing location and sorry, it was dark when I got there so no pictures. It was mild that night, around 44 degrees F and that fell down to around 26 degrees F when I got done. I visited some old friends that night and here is what I got.
1. M1 The Crab Nebula. November 17th, 2017 FR006 Juniper Grove: Antoniadi I; 17.5" dob with 10mm & 5mm Pentax XW. Paracorr Type II.
Messier 1 showed to me good structure in the 17.5" dob. A slight brightening in the center was observed and my UHC filter brought out structure on the edge and on the center. My OIII brought out what appeared to me as filament structure. A fun observation tonight, getting the most out of my mirror, my eyepieces and the structure of the object.
2. It's been awhile since I sketched an open cluster so tonight I hopped over the Messier 46 and captured the planetary nebula there NGC 2438 which is round in nature and more ring like to me.
NGC 2438 and Messier 46. November 17th, 2017. FR006 Juniper Grove; Antoniadi I; 17.5" dob with 10mm Pentax XW, 22mmT4 Nagler and 26mm Nagler T5 with Paracorr Type II.
3. Messier 74 a Face on Spiral Galaxy; November 17th, 2017, FR006 Juniper Grove; Antoniadi I, 17.5" dob with 7mm, 10mm Pentax XW and 22mmT4 Nagler, Paracorr Type II.
I love observing this object and its been about 4 years I believe since I last saw it. Spiral structure was easily observed at high magnificaion and even in the 22mmT4 Nagler, I made out easily spiral structure. Again, just a fun galaxy to study.
4. Messier 103, Open Cluster. November 17th, 2017, FR006 Juniper Grove; Antoniadi I, 17.5" dob with 10mm Pentax XW and 20mm Pentax XW and 22mmT4Nagler with Paracorr Type II.
Again, doing some open cluster work this night and here I used colored pastel pencils to place the stars and their colors and focused on blue and orange as my colors. I enhanced these images in GIMPa and their colors, and in the bottom one, added the dazzle affect to try to recreate how this wonderful open cluster looked at the eyepiece.
5. Messier 15, Globular Cluster, November 17th, 2017; FR006 Juniper Grove, Antoniadi I, 17.5" dob, with 7mm, 10mm Pentax XW and 22mmT4 Nagler. Paracorr Type II.
I have never been happy, and still am not with my sketching of Globular clusters. This is improving and I realized that I need to vary my star size and make more of my stars fainter and some more brighter to get that 3D affect. Overall not a bad view and I did again for the second time, capture Pease 1 the PN in Messier 15 and that took up a good share of time. More on that in another post perhaps, but I was pleased to successful have found and observed Pease 1 again.
6. NGC 1360 The Robin's Egg Nebula. November 17th, 2017; FR006 Juniper Grove; Antoniadi I; 17.5" dob with 5mm, 7mm, 10mm Pentax XW and the 22mm T4 Nagler as the finder. Paracorr Type II also.
Two versions of the is planetary nebula. The first one is my finished version with color added in to it and really reflects what I saw in the eyepiece. The bottom one was the sketch without color, and it also gives a really good affect of what you see on this object as well.
7. NGC 1055 edge on Spiral Galaxy in Cetus. November 17th, 2017, FR006 Juniper Grove; Antoniadi I; 17.5" dob with 10mm Pentax XW and 7mm Pentax XW, with 22mmT4Nagler and Type II Paracorr.
NGC 1055 Galaxy in Cetus. It has been 7 years since i visited this galaxy and this time the larger aperture and darker skies than those of Pit n Pole showed and revealed more. The dust lanes are more evident in the sketch than in my observation, I could tell and see they were there Did this one digitally and again, I like my original sketch better.
8. NGC 869 & NGC 884, the Double Cluster; November 17th, 2017; FR006 Juniper Grove; Antoniadi I; 17.5" dob with 22mmT4Nagler & 26mm T5 Nagler with Type II Paracorr.
It has been over 10 years since i tried to sketch the Double Cluster and tonight, I figured why not. The first sketch is the sketch I did while at the eyepiece, and the one below it, I tried to cross the brighter stars which isn't realistic since my 17.5" dob has a curved vane, not a traditional 4 cross vane on its spider. Oh well, a little fun. The top sketch I prefer anyway.
9. NGC 7662 The Blue Snowball, a Planetary Nebula. November 17th, 2017; FR006 Juniper Grove, Antoniadi I; 17.5" dob with 10mm & 5mm Pentax XW and Paracorr Type II.
The blue snowball really showed itself tonight and the color was evident. I tried both a OIII and UHC Narrowband filter and they brought out more of the shape or dimmed it and showed a hint of the outer shell, but the dark site and larger dob brought out the best view without a filter. I always enjoy this object.
10. NGC 256 The Skull Nebula, a Planetary Nebula; November 17th, 2017; FR006 Juniper Grove; Antoniadi I; 17.5" dob with 10mm & 14mm Pentax XW, 22mmT4 Nagler and Paracorr Type II; OIII and Narrowband Filters by 1000 Oaks and DGM.
Fantastic object this night! Central star was easily observed and the PN seems to have a brighter out edge with a lot of fainter material in the central region by the star. Some parts of the central region showed no structure or evidence of structure. This is a large Planetary Nebula that is about 6 light years across and easy to pass by if your not sure what your looking for or for faint DSO's. Fun object to play and tease with. Tried my OIII which brought out some structure and my DGM and 1000's Oaks Narrowband which dimmed it, but brought out some of the brighter portions.
On July 15th, 2015 I wrote a blog entry about RNe M31N-2008-12a, a recurrent nova in our neighboring galaxy Messier 31, the Andromeda Galaxy LINK. Well its fall now, and either in the midst of or past what should be the expected annual or six month outburst for this ever increasing White Dwarf as it feeds mass from it's Red Giant Star companion. This table will show the expected time frames when this binary WD (White Dwarf) and RGC (Red Giant Companion) are expected to have an outburst. The -a after the year is when the first outburst is expected, based on data, though never observed or confirmed by observation yet. The -b are the second or annual outburst that have been observed and recorded since 2008 and also confirmed via archival data from 1992, 1993 and 2001.
You can see here, that based on data gathered by observations made by Chandra, the Kiso
Schmidt Telescope, the Okayama Telescope, the MiyakiArgenteus Observatory, all in Japan; the Xingming Observatory, China; the Ondˇrejov Observatory, Czech Republic; Montsec Observatory, Spain; and the Kitt Peak Observatory, USA, that the observed time between measured outbursts is 351 ± 13 days though the team led by M.J. Darnley believes the true value to be half of this. Thus the reason for the -a listings. This is based on observations of eruptions that were identified starting in 2008, with eruptions having a recurrent period of 347 +/- 10 days (Darnley et al. 2016a). When archival X-ray detections of eruptions in 1992, 1993 and 2001 (Henze et al. 2014) are factored in, the evidence is very strong that the real recurrence period is more likely 174 +/- 10 days or half of what it is currently. One reason we may not see these is Andromeda, M31 is close to the Sun from March through May. If the second occurrence occurs during this time frame, and it seems it most likely would, the Sun is most likely blocking us from seeing the second outburst each year. It does indicate though that the white dwarf is close, really close to the Chandrasekhar limit of 1.4 solar masses. That means a Type Ia supernova or a direct collapse into a neutron star if neon is present in the white dwarf.
Novae are powered by thermonuclear runaway occurring at the base of an acreted layer at the surface of a white dwarf (WD) star. The white dwarf star is formed when a star, between the size of our Sun to 8 or perhaps 9 times the mass of our Sun, ends it life by going through the Red Giant branch of its life. The star ran out of hydrogen to burn and so contracted due to gravity. As fusion again begins to burn, this causes radiation pressure and the star now expands. The outer layers of hydrogen in the star redden and the star assumes more of a red appearance, thus due to the expansion and growth, becomes a Red Giant or RG. That contraction allowed hydrogen around the helium core to ignite It sheds its outer layers via the process As a star like our Sun burns through its hydrogen layer, it begins to contract as the hydrogen fuel is used up. This usually is around 8 to 10 billion years into the stars life. This image reflects this process.
At this point, the helium core of the red giant becomes highly dense to the point that the core cannot expand anymore. As the hydrogen envelope around the core continues to bring heat, the core as being degenerate now cannot respond and temperature becomes high enough that the helium nuclei begin to fuse into carbon via the Triple Alpha process.
Image Credit: Borb/CC
The carbon can then fuse with helium nuclei to become oxygen and neon. As stated for many of these red-giant stars, the core will not change its size nor will it cool. The most common red giants are stars on the red-giant branch (RGB). RGB stars are still fusing hydrogen into helium in a shell surrounding an inert helium core. Other red giants are the red-clump stars in the cool half of the horizontal branch, fusing helium into carbon in their cores via the triple-alpha process (see above); Finally we have the asymptotic-giant-branch (AGB) stars with a helium burning shell outside a degenerate carbon–oxygen core, and a hydrogen burning shell just beyond that. Stars less than about 10 times the mass of the Sun become asymptotic-giant branch stars - red giants with inert, degenerate carbon/oxygen cores, which are fusing helium in the shell around the core. This helium fusion causes the star to become unstable and the envelope is ejected as a planetary nebula. This LINK provides a good overall view of the process of converting a Sun like star into a Red Giant.
A cataclysmic variable or CV novae occur in close binary systems, perhaps roughly the size of the Earth-Moon system, maybe slightly larger or smaller. The White Dwarf or WD accretes material for its companion, usually via an accretion disk around the WD. The companion can be a Sun like star to a Red Giint Star. Here our WD has already gone through the stages of a stellar like star like our Sun, evolved, ascended up the Red-Giant branch and thrown off its envelope with only the white dwarf (WD) left behind. The companion in M31N 2008-12a is now a Red-Giant itself, have evolved to that point and via a stellar wind is sharing or accretting mater unto the white dwarf. As the material builds, it reaches a point where an the carbon and oxygen begin to fuse so quickly that this causes an eruption. That eruption Since this CV novae has such a short recurrence period, this infers that the WD in M31N 2008-12a must be a high mass, perhaps the highest mass WD yet found in a CV system. The unveiling of the super soft source or SSS X-ray emission after each eruption of just six days, again points to a low ejected mass combined with the short duration of the SSS of about 19 days, further supports the notion that this is a high mass WD. As a result the work of Tang et al. (2014) and Kato et al. (2015) indicates that the mass of this WD will reach the Chandrasekhar mass of 1.4 solar masses in less than 1 million years (1 Myr).
Whether this system ends up as a SN Type Ia or ends up as a neutron star will be determined by the composition of the WD. An oxygen neon white dwarf will result in a neutron star when the WD reaches the Chandrasekhar mass of 1.4 solar masses, and the WD will collapse right into the neutron star. If the WD is composed of carbon and oxygen then it will result in a SN Type Ia when it reaches the Chandrasekhar mass of 1.4 solar masses. The work of Hillman et al. (2016) shows that a carbon oxygen white dwarf can grow from its initial formation mass of < 1.1 solar masses to the Chandrasekhar mass of 1.4 via a long series of hydrogen flares (novae) interspersed with helium flashes or He-novae with little to no tuning of the system parameters or accretion rate. This has significantly strengthened the case for novae contributing to the SN Ia progenitor population.
The companion to the WD based on compelling evidence from the spectral lien development, to the coronal emission lines, to the Raman emission band and the photometric behavior of each eruption point to red giant with wind accretion in this system. Further, the distance from the RGC (Red Giant Companion) to the WD is most likely short, resulting in an accretion disk that survives each eruption, allowing for the WD to accrete mass very shortly after the eruption. The accretion disk must be particularly massive, with a Red Giant donor with a high mass accretion rate and accretion disk luminosity,. With at least one annual and most likely two eruptions every year occurring in M31N 2008-12a since at least the early 1990's, astronomers have raced to find the missing eruptions. This has led to the Liverpool Telescope or LT led by Steele et al., observing and discovering a shell like elliptical nebula centered on the nova. It is large, very large, measuring 130 pc along the major axis and 90 pc across the minor axis.
To show how large that is, we know that a parsec is roughly 3.26 light years or 19 million miles (31 trillion km). At 130 pc that means 2.47 billion miles or the distance from Earth to the planet Neptune. The minor axis would be 1.71 billion miles or the distance from the Sun to Uranus. Darnley et al. (2015) proposed this extended nebulosity is the super-remnant of many thousands of past eruptions from M31N 2008-12a. Hydrodynamic simulations of the formation of such a phenomena are underway and support this hypothesis. Ten orbits of the Hubble Space Telescope Cycle 24 time was awarded to study the structure and possible formation pathway of the super remnant and this was to have taken place in December of 2016.
The key remaining determination is the composition of the WD itself. Is the WD composed of Oxygen and Neon, leading to the formation of a neutron star when the Chandrasekhar mass limit of 1.4 is reached. Again, if the WD is composed of Oxygen and Carbon then the final destination will result in a SNe Type Ia when the Chandrasekhar mass limit of 1.4 is achieved. Regardless, M31N 2008-12a is the leading candidate for a pre-explosion SN Ia progenitor. If confirmed, the super-remnant nebula that is around M31N 2008-12a may exist around all RNe (recurrent novae) and may be a glaring sign that points to a SNe Ia and thus lead us to an avenue of identifying the progenitor type of Type Ia supernova, or a collapse neutron star WD scenerio.
M31N 2008-12a has been compared to RN V745 Sco, a Recurrent Novae in our galaxy perhaps M31N 2008-12a closest cousin. RN V745 Sco has a RG companion and like M31N 2008-12a is fueled by wind accretion from its RG companion. Thus it is easy to compare the two. RN V745 Sco has undergone observed/detected eruptions in 1937, 1989 and most recently 2014. This results in a period of 25 years between eruptions. It is assumed based on the fact that peak luminosity reaching only 10th magnitude that some eruptions may have been missed on RN V745 Sco.
RN V745 Sco has a faster SSS turn-off and the shortest SSS phase of any observed nova so far. It appears that the SSS phase only lasts until day 10 for RN V745 Sco vs day 18 for M31N 2008-12a and shows that less matter is ejected in RN V745 Sco than M31N 2008-12a and that a smaller amount of hydrogen is needed in RN V745 Sco to trigger an eruption, making the mass of the WD there more massive than the WD in M31N 2008-12a. However the WD in M31N 2008-12a would be accreting more mass during its eruptions and moving more rapidly toward the Chandrasekhar mass of 1.4. Bottom line though the WD in RN V745 Sco is most likely gaining mass and is yet another good candidate for a SN Type Ia progenitor.
V745 Sco and M31N 2008-12a are two extreme RNe that share several observational characteristics. They are:
Both objects low mass ejecta appear to interact strongly with the stellar wind from the RG companion, slowing significantly in the process and producing high temperature shocks.
Their SSS spectra extend to high temperatures and appear to feature strong, variable emission lines.
While the WD in V745 Sco may be more massive, the WD in M31N 2008-12a appears to have the higher accretion rate, providing the unique opportunity to observe at least one eruption per year, most likely two.
Assuming that V745 Sco has a 25 year cycle in eruptions, the next eruption in V745 Sco will occur around 2039, which means that astronomers will have studied M31N 2008-12a sufficiently to provide detail predictions on the variations on the eruption properties of V745 Sco.
So, I have quoted a lot from the articles and will now attempt a layman's explanation of why M31N 2008-12a is so important in our understanding of Recurrent Nova (RNe) and progenitor of Type Ia SNe. Discovered in 2008 with an eruption from the WD in the system, this RNe has erupted every year since 2008. Archival evidence points to eruptions in 1992, 1993 and 2001, while pointing to a huge elliptical nebula around the WD that measures from the Earth to Neptune on the minor axis and from the Sun to Uranus in its major axis. Here is that visually:
That is a significant size nebula which has resulted from thousands of eruptions and the wind coming off the Red Giant companion. A large accretion disk exists centered around the WD with material coming from the companion Red Giant from the wind put off by the RGC. This mass accretes unto the WD until it erupts, at least once a year, most likely twice a year. The accretion disk survives the eruption and the WD in M31N 2008-12a rapidly begins to acquire mass, hurtling it to a cataclysmic day of reckoning sometime within the next 1 million years. This nebula may be a leading reoccurring feature of RNe that are progenitors to a Type Ia SN explosion as we can see in M31N 2008-12a's cousin, RN V745 Sco. M31N 2008-12a is the best identified progenitor for a Type Ia SN in Messier 31, the Andromeda Galaxy that has been identified to this point. Whether M31N 2008-12a ends up as a Type Ia SN or becoming a Neutron Star will depend on its composition. If the WD in M31N 2008-12a is an Oxygen Neon composition, we will end up when the WD reaches 1.4 solar masses, with a neutron star. If the WD is a Carbon Oxygen composition, then when the WD reaches 1.4 solar masses, we will end up with a SN Type Ia supernova.
Either way, the science behind and the journey of identifying the evolution of this white dwarf, and its final destination is perhaps the most enjoyable aspect of what is occurring here. Would I love in some future fall day, at new moon or other, to point my 24" or 17.5" up at Messier 31, the Andromeda Galaxy and observe a Type Ia Supernova going off in the location where M31N 2008-12a exists? Absolutely. However, a million years is very short time period in terms of Astronomical Units and measurement, in a human lifespan, that is forever. It may be up to some future astronomer and perhaps an amateur astronomer to discover this system when and if it goes Supernova. However it is fun to point to the sky to the general location, to take a peak even if you can't see it in your telescope at mag. 17 to 21, but knowing what is going on, what has gone on, what will most likely occur should make this object enjoyable when it does go off.
I've made two sets of drawings digitally to show the system and what could occur. Realize no details are meant to be exact and the images are made for my blog, are owned and copyrighted by me. So here we go.
Above is M31N 2008-12a with the Red Giant companion feeding material to the White Dwarf via a solar wind and a very large nebula and accretion disk forming around the White Dwarf.
Above shows the White Dwarf, having accreted mass, going into eruption and shedding that mass from the accretion disk. Some of that matter will remain increase the mass of the White Dwarf and sending it further on its way to the Chandrasekhar limit of 1.4 solar masses.
Here the WD is now in full eruption/outburst and the brightness dims the nebula and accretion disk which does survive.
The eruption begins to fade and the system begins toward "normal."
Back where we stated.
Some future day we head to what appears to be another eruption . . .
In reality, the White Dwarf in M31N 2008-12a has exceed the Chandreasakar limit of 1.4 solar masses and being composed of Oxygen and Carbon, the White Dwarf explodes into a Type Ia SN.
Here is the second set of images.
Here is the Red Giant with the White Dwarf accretion material and I have tried to make a wind visible in the image.
Here is how I have made the eruption appear off the White Dwarf.
Again, one day the White Dwarf, composed of Oxygen and Carbon exceeds that Chandrasekhar limit of 1.4 solar masses and explodes into a SN Type Ia.
The SN Type Ia occurs
For affect, and realize the SN Type Ia would have faded I am sure by this time, but I wanted to show the companion Red Giant being hurled away from the SN Type Ia with material (X-ray) that was stripped off of its surface out in front and a debris shadow. The Red Giant companion would be heading in a direction to the upper right or lower left with the material and debris shadow in this case heading to the lower right.
I published before what I believed was the location but using Simbad and the tools there I believe I have a much closer location. Here are those images.
1. The purple cross hairs show in the Andromeda Galaxy, M31 the location of M31N 2008 12a or RX J0045.4+4154 as it is known on charts.
2. This next image sows a similar view but now we are starting to move in on the objects location.
3. Here I use an online free tool called Greenshot to insert some lines to show some possible star hoping points to get in close to M31N 2008 12a.
4. Stars and hops 1 & 2 are the two larger stars below and to the left of M31N 2008 12a in the image right above. Now I have zoomed in even more, identifying M31N 2008 12a's location and provided a star hop to the general area.
4a. Another view of the star hop to get closer in to this object. Note the double stars (I haven't looked them to confirm if they are a double pair) and then the hops to the two stars, 2 and 3 and then you can go to 4 and 5 and down or work your way up from 3. Your choice!
5. Below you can see the close in section and location of M31N 2008 12a. You can see the triangle of brighter stars to the upper left, two stars in a somewhat off angle line below and slightly to the left, and a bright star with two faint stars above it to the right and slightly down. In 20,000 years or so if math and science are correct, we will observe a Type Ia Supernova if this is a Carbon Oxygen White Dwarf, or a White Dwarf Collapse to a Neutron Star if this is a Neon Oxygen White Dwarf. So far I think it points to a Carbon Oxygen WD as no signs of Neon have been detected in the Spectra but we may not be picking it up, so all bets are off to the final object that is created from this.
6. Here I have put in some green lines that angle and could help someone get closer in to where this object is if they are wanting to do that.
There is a lot more on this object and if you search the net, you'll find it. I intend to keep following the object and see what science learns from observing it as it is fascinating to me.