Well as I have posted, on December 31st, 2017, Recurrent Nova M31N 2008-12a erupted again for the 10th recorded time, though this recurrent Nova in the Andromeda Galaxy, M31, has probably been doing this for million of years. It is close, getting closer to either collapsing into a neutron star when it reaches the Chandrasekhar limit of 1.4 (1.44) solar masses if it is a Neon/Oxygen White dwarf, or into a Type Ia Supernova if the progenitor white dwarf is a Carbon/Oxygen White Dwarf. So far not spectra of Neon has been detected but we probably won't know until 20,000 years or so in the future when the event actually occurs. Okay, we won't know but our descendants will know.
The drawing above shows an exagerrated RN M31N 2008-12a as a bright reddish star on the left middle of the sketch. The rest of the sketch is my impression of the the extreme massive nova remnant that is brighter on the western side and arch and has filaments and other portions attached to it. This is based off of the XRay Data observation from the NASA Spitizer Space Telescope. Remember this is about as long as the Pleiades are from the Earth, thus a massive nova cloud.
Here you see again the large red dwarf companion and I have not included material moving on a accretion disc from the red dwarf companion, and instead have included a wind that is moving material off the red dwarf and that is accretting material onto the white dwarf star which you can see. This is causing a build up of material on the white dwarf that ends in either the confirmed annual eruption of late December each year, or a bi-annual eruption with the second eruption occurring in the spring when material has built up, resulting in an eruption that is blocked from being seen because of the position of Messier 31 and our Sun, which acts to block this event each year.
If you look at the material being blown off by the wind, using direct and averted vision I have tried to capture various layers of material being blown off and I think I have captured that nicely. I am fascinated by this object, and similar objects now in the Milky Way. I am working on a piece to share some of the closer and similar objects that are in our own Milky Way Galaxy. Truly our understanding of these complex systems is just beginning to emerge and the ground work being laid down here will impact future astronomers for a very long time!
I got some observing in on December 18th and 19th, 2017 out at my dark site off of Forest Road 006 at Juniper Grove. A couple of images.
A little snow on the ground but the ground was dry and not wet on this trip out. Some clouds at firt over the Sheeprock Mountains that went away as night came on. A few bones on the site from a deceased animal. Only a couple and I moved them out and away from where I observe.
The 17.5" Dob "Star Catcher" ready to go. The clouds are gone.
Observations occurred on December 19th through December 21st, 2017. Location is Forest Road 006 Juniper Grove. Time is from 17:30 to 04:00 on those days. Conditions were Antoniadi II, with temperatures ranging from a low of 3 degrees F to an more warmer average of between 16 degrees F to 19 degrees F. Instrument was my 17.5" dob, Star Catcher.
I am making the sketches larger, they will go off the right side of the posting area so you can view them easier. We'll see how I like this set up. Off to work!
1. NGC 266 Face on Spiral Galaxy in Pisces. 22mm T4 Nagler, 7mm & 5mm Pentax XW, Paracorr Type II. NGC 266 is a bright, moderately size face on spiral galaxy that has a bright inner core, with a brighter bar seen. I captured hints of the spiral structure coming off the eastern arm, with a hint of another arm coming off the western arm. I have probably over emphasized the arms in the sketch but they were faintly observed.
2. NGC 274 and NGC 275 or ARP 140, galaxies in Cetus. 22mm T4 Nagler, 7mm Pentax XW, Paracorr Type II. NGC 274 is the brighter of the two galaxies and it is the upper top one in the sketch. NGC 274 in contrast to NGC 275 is round, has a bright inner core and well defined edges.
NGC 275 is more oval, more diffused and larger and elongated SE-NW. Bright core wit a blending of brightness, maybe a hint of an arm unconfirmed.
3. NGC 392, NGC 394, NGC 397 Galaxies in Pisces, 22mm T4 Nagler, 7mm Pentax XW, Paracorr Type II. NGC 394 is the top small, faint galaxy; NGC 392 is the large central galaxy, NGC 397 is the faint galaxy down and to the left of NGC 397.
NGC 392 is the brightest of these three galaxies though that isn't saying much. It is elongated SW-NE, with edges that are diffused and is grainy in its texture.
NGC 394 is very faint, and a condense round patch of light.
NGC 397 is roundish, decently bright and well defined.
4. NGC 410 & NGC 407 galaxies in Pisces. 22mm T4 Nagler, 7mm & 5mm Pentax XW with Type II Paracorr.
NGC 410 is a relatively medium size galaxy that is rather bright. NGC 407 is next to 3 stars and is a smudge.
5. NGC 07, NGC 508, IC 1687, NGC 504 with 22mm T4 Nagler, 7mm Pentax XW, Paracorr Type II
NGC 507 shows an outer envelope and an inner envelope and is brighter toward the center though the center's brightness is smaller in size. This is the largest galaxy in the field.
NGC 508 is a faint, round galaxy with an inner core appearing as a condense area of light at the center.
IC 1687 is very faint, averted vision required to view it.
NGC 504 is elongated SW-NE no structure evident and is a patch of light.
6. NGC 660 Galaxy in Pisces; 22mm T4 Nagler with 5mm & 7mm Pentax XW, Paracorr Type II.
NGC 660 is a large and beautiful galaxy being oriented SW-NE. It has a very bright bar elongated SW-NE. The NE portion of the bar is very bright with a high surface brightness. The galaxy brightness diminished and becomes fainter and wider in the SW part of the bar and is fanning out from there. Central region is very mottled and dusty. The X looked more like a Y to me on the bar. Second faint arm on the NE and bends in the west giving the galaxy a warped S shape.
7. NGC 827 Galaxy in Cetus: 22mm T4 Nagler, 7mm Pentax XW, Paracorr Type II
Elongated almost perfectly laying east to west with tapered edges, and a diffused, opaque outer envelope. There is some brightening near the core.
8. NGC 894 a Galaxy in Cetus: 22mm T4 Nagler, 5mm & 7mm Pentax XW, Paracorr Type II
NGC 864 is a really interesting galaxy visually, especially at high magnification. A magnitude 10 star is imposed/embedded on the galaxy ESE of the core, almost overcoming the galaxy's bright core. The envelope is is diffused, round to oval in shape, more oval to me, elongated NE-SW to E-W. The inner core has a bar and the core appears round. Averted vision brings hints of structure in terms of arms.
9. NGC 908 a galaxy in Cetus. 22mm T4 Nagler, 5mm & 7mm Pentax XW, Paracorr Type II.
NGC 908 has a very grainy outer envelope at high magnification, 600x-800x. It is very large, very bright with well defined edges, and is elongated ENE-WSW. Spiral arms are easily viewed and in evidence.
10 NGC 1044 & NGC 1046 Galaxies in Cetus. 22mm T4 Nager, 7mm Pentax XW, Paracorr Type II.
NGC 1044 is the top and larger galaxy in the sketch. It is more roundish in shape to me than oval. Really, it is just a patch of fuzz in the eyepiece.
NGC 1046 is smaller, fainter and more round. Another faint fuzzy patch of light.
11. NGC 1070 Elliptical Galaxy in Cetus. 22mm T4 Nagler, 7mm Pentax XW, Paracorr Type II.
NGC 1070 is a larger galaxy with a diffused outer envelope and a brighter interior. Poor star field around it.
12. NGC 1084 Spiral Galaxy in Eridanus; 22mm T4 Nagler, 5mm & 7mm Pentax XW, Paracorr Type II;
NGC 1084 is well defined at the edges, opaque with brighter mottling over much of the disc of the galaxy. It is both bright and large. Structure is evident, arms are defined at high magnification and with averted vision. Great view!
13. NGC 1153 Galaxy in Cetus; 22mm T4 Nagler, 7mm Pentax XW, Paracorr Type II.
NGC 1153 has a diffused outer envelope with a sharp, round core that is almost, not quite, but almost stellar. Round to oval in shape, more oval to me (seem more are more oval to me on this observing trip).
14. NGC 1232 Spiral Face On Galaxy in Eridanus; 22mm T4 Nagler, 5mm & 7mm Pentax XW, 4mm University Orth; Paracorr Type II.
NGC 1232 is moderately large face on spiral galaxy (a grand spiral) and moderately bright. The galaxy brightens to a central core region visually and that core is well in evidence. Bar possibly observed here and hinted at in the sketch. Spiral structure is easily seen and sketched here. Wonderful at high magnification in a large dob.
15. NGC 1395 Elliptical Galaaxy in Eridanus. 22mm T$ Nagler, 5mm & 7mm Pentax XW, Paracorr Type II.
NGC 1395 is an elliptical galaxy with an outer envelope that is faint, and a bright and somewhat large inner core region.
16. NGC 1407 & NGC 1400 Elliptical Galaxies in Eridanus; 22mm T4 Nagler, 12mm TeleVue Delos, 7mm Pentax XW; Paracorr Type II;
NGC 1407 is the largest galaxy in this view, it is round, opaque patch of light with a large round, non-stellar core.
NGC 1402 is WNW of NGC 1407 and is viewed as a faint fuzzy, almost stellar, patch of light.
NGC 1400 is smaller than NGC 1407, down and to the right in the sketch, and is viewed as being brighter than NGC 1407 which is due to its smaller and more compact concentration. The galaxy is opaque with a bright even surface brightness in its outer envelope.
17. NGC 1600 Elliptical Galaxy in Eridanus; NGC 1601 & NGC 1603 galaxies in Eridanus. 22mm T4 Nagler, 12mm Televue Delos, 7mm Pentax XW, Paracorr Type II.
NGC 11600 is a bright galaxy and is elliptical with a bright inner core region. NGC 1603 & 1602 are smudges of brighter light, easy to see in the field.
18. NGC 1624 or Collinder 53, Open Cluster in an Emission Nebula in Perseus. 22mm T4 Nagler, 10mm & 7mm Pentax XW, 12mm Televue Delos; Paracorr Type II.
Bright and large emission nebula surrounding five main stars with smaller ones evident in the open cluster. NGC 1624.2 is the largest star in the open cluster and is responsible and the source for the ionization that is lighting up the emission nebula. NGC 1624.2 is the most magnetic massive star known, 35 solar masses and 20,000 times our Sun's magnetic field. The open cluster is very young estimated at less than 4 million years old. The emission nebula is easily seen and detail is evident. Looking carefully you can see how the emission nebula fades into the intergalactic background. This is one where the sketch in person is far better than the image captures as you can see more detail and faint detail in it.
19. NGC 1637, Face on Spiral Galaxy in Eridanus; 22mm T4 Nagler, 7mm Pentax XW, 12mm Delos, Type II Paracorr;
This is a very large and very bright spiral galaxy. The 22mm T4 Nagler easily detected the galaxy in its field of view. The edges and extremities fade into the sky background nicely. It is elongated NNE-SSW, the high magnification used shows a mottled core with bright extensions, Arms are evident.
20. NGC 1700 Large Elliptical Galaxy & NGC 1699 Spiral Galaxy in Eridanus; 22mm T4 Nagler, 10mm & 7mm Pentax XW; Paracorr Type II.
NGC 1699 is on the upper top middle of the sketch and is a concentrated focus of light, a faint fuzzy with no structure except a well defined edge.
NGC 1700 lays NNE to SSW while the core lays E-W. It is a young Elliptical Galaxy, possible from a merger from a smaller elliptical galaxy and a spiral galaxy and images from Chandra show a rotating disc of hot gases. The outer elliptical is bright, the inner core brighter and almost stellar in lower magnifications.
21. NGC 1961 or ARP 184 Spiral Galaxy in Camelopardalis. 22mm T4 Nagler, 7mm Pentax XW, Type II Paracorr.
NGC 1961 is a distrubed spiral that is large, oval in shape and lays East to West. It has a very bright oval core that is offset to the northern part of the galaxy. Large arm is visible sweeping East to West, on the south side of the galaxy. Broad dust lane runs parallel on the inside of this arm. Small arms possible north to west, running west to south. Nice view. Again, here the original sketch is better than the photograph image above as the actual sketch has more subtle features and brighter and fainter parts stick out more. Still learning the camera I am using but the image is better that what I use to post.
22. NGC 1609, NGC 1611, NGC 1612, NGC 1613 Galaxies in Eridanus; 22mm T4 Nagler, 14mm Pentax XW, 10mm Pentax XW, 12mm TeleVue Delos, Paracorr Type II.
NGC 1609 is a very small and faint galaxy that has a small condense and bright core, good stellar nucleus can be seen.
NGC 1611 is a small, faint elongated WNW-ESE with a large bright core.
NGC 1612 is a very faint, small, round shape galaxy that has a faint stellar nucleus and is the faintest galaxy in the group and in the sketch.
NGC 1613 is small, faint, partially elongated SE-NW. Bright core with a stellar nucleus.
21. NGC 496, NGC 195, NGC 499, NGC 498 Galaxies in Pisces; 22mm T4 Nagler, 10mm & 7mm Pentax XW; Paracorr Type II.
NGC 498 is a very small, extremely faint fuzzy galaxy with no details.
NGC 496 is a faint, oval shape patch of light, elongated NE-SW.
NGC 495 is the western part of this triangle of galaxies and has a bright inner core region though it is a small galaxy.
NGC 499 is the largest of the 3 galaxies, is a barred spiral but we cannot see the bar or arms visually, we cannot see any structure, and it is elongated just off the W-E line. Oval in shape.
Recurrent Nova M31N 2008-12a has been discovered in eruption for the 10th year in a row. This occurred on December 31st, 2017 and this post is just to share information from the ATel's about it for those who are interested in following it. The initial report and can be viewed at this ATel LINK. There it states:
The nova was clearly detected on 2017-12-31.77 UT using 26 x 30s images obtained with a 0.35-m Meade Schmidt-Cassegrain Telescope, working at f/6.3 with a clear filter and a Starlight Xpress SXVR-H9 CCD camera, at the West Challow Observatory UK. The discovery magnitude is 18.41±0.04 mag in the CV band (clear visual). The discovery was confirmed at the Ondrejov observatory. We will continue to monitor the nova light curve and strongly encourage additional follow-up observations.Further observations are found at this ATel from December 31st, 2017 LINK2 It states:
A January 1st, 2018, ATel reports this LINK3 .The Liverpool Telescope (LT; Steele et al. 2004) obtained a 600s SPRAT (Piascik et al. 2014) spectrum of this eruption at Dec 31.88 UT.This spectrum shows clear detection of Hα, Hβ, Hγ, and Hδ emission lines on top of the detected continuum. The spectrum is similar to the early time spectra obtained after the 2015 (Darnley et at. 2016) and 2016 eruptions (Henze et al. submitted). This spectrum confirms that this transient event is the 2017 eruption of M31N 2008-12a.
On January 2nd, 2018 in this ATel observation LINK4 by the Swift Telescope were reported on this Recurrent Nova. Kinda of cool what it shares here.We report multi-color CCD photometry of the recurrent nova M31N 2008-12a, obtained near the peak of its most recent eruption (ATel #11116). The data, which were acquired with the CCD imaging camera on the 40-inch reflector at San Diego State University's Mount Laguna Observatory, yielded the following magnitudes:UT Date (mid exp) Exp (s) Filter Magnitude 2018 Jan 01.076 300 V 18.06 ± 0.09 2018 Jan 01.080 300 B 18.40 ± 0.25 2018 Jan 01.084 300 R 18.27 ± 0.03 2018 Jan 01.302 300 R 18.31 ± 0.04 2018 Jan 01.306 300 V 18.29 ± 0.15 2018 Jan 01.309 300 B 18.44 ± 0.40
Within the framework of a comprehensive monitoring campaign we obtained the first UVOT data of the 2017 eruption on 2018-01-01.22 UT; only 11 hours after the discovery on 2017-12-31.77 UT (ATel #11116). The nova was clearly detected with a uvw2 filter (Vega) magnitude of 17.2±0.1 mag (uvw2 central wavelength 193 nm) in a 1-ks observation.This ATel from January 3rd, 2018 shows more multicolor optical photometry of the 2017 eruption. LINK5 This shows the rapid falling of the Nova as was observed in previous eruptions.
The magnitude estimate is preliminary, assumes the UVOT photometric system (Poole et al. 2008), and has not been corrected for extinction. Nothing is detected in the corresponding Swift XRT exposure. We will continue to monitor the UV and X-ray evolution of this exceptional nova.
This ATel from January 4th, 2018 shows more optical photometric observations of the 2017 eruption. You can find it at this LINK6.We report additional multicolor optical photometry of the 2017 eruption (ATels #11116, #11117, #11118, #11121) of the remarkable recurrent nova M31N 2008-12a (Henze et al. 2014, 2015a, 2015b; Darnley et al. 2014, 2015, 2016) acquired with the 0.65-m telescope at the Ondrejov observatory under variable conditions. For the measurements, we used co-added images obtained from many single 90-s exposures to suppress the effect of high background caused by strong moonlight. The results presented below are consistent with the expected rapid fading of the nova observed during previous eruptions (e.g. ATels #9848, #9861 or ATels #7964, #7976).Date UT Band Magnitude Total exposure [s] 2018 01 01.723 V 18.91 ± 0.08 1800 2018 01 01.840 V 19.03 ± 0.08 2070 2017 12 31.829 R 18.18 ± 0.09 1260 2018 01 01.682 R 18.50 ± 0.08 1080 2018 01 01.796 R 18.57 ± 0.06 1350 2018 01 01.864 R 18.60 ± 0.05 1800 2018 01 02.768 R 19.37 ± 0.14 1170 2018 01 02.921 R 19.42 ± 0.11 3510 2018 01 01.701 I 18.24 ± 0.09 1800 2018 01 01.816 I 18.43 ± 0.10 1800
The January 5th, 2018 report found in this ATel LINK7 has some good information on it. It reports:
The next ATel on January 6th, 2018 reports additional multicolor photometry of the 2017 outburst of Recurrent Nova M31N-2008-12a. It gives a clear view of the rapid brightening and then rapid fading of this remarkable recurrent nova.In ATel #11116 we announced the discovery of the predicted 2017 eruption of the recurrent nova M31N 2008-12a on 2017-12-31.77 UT. We reported the follow-up UV detection with Swift/UVOT in ATel #11121. This is the 10th observed eruption in 10 consecutive years of this unique nova system (cf. ATels #5607, #6527, #7964, #9848). Comprehensive multi-wavelength studies of previous eruptions were published by Darnley et al. (2014, 2015, 2016) and Henze et al. (2014, 2015a, 2015b, 2018 subm.). For additional optical photometry and spectroscopy of the ongoing eruption see ATels #11116, #11117, #11118, #11124, #11125, #11126.Here we report the start of the supersoft X-ray source (SSS) phase of M31N 2008-12a. A faint X-ray counterpart was detected in a 5.2-ks Swift observation starting on 2018-01-05.48 UT. We measured the preliminary XRT count rate to be (3.1±1.0) × 10-3 ct/s (corrected for vignetting, dead time and PSF). No X-ray source was detected in the preceding 1.2-ks Swift observation on 2018-01-04.48 UT with an 3σ upper limit of 6.0 × 10-3 ct/s.If we assume an eruption date of 2017-12-31.77 UT (MJD 58118.77), identical to the discovery date (ATel #11116), then the SSS counterpart appeared around day 4.7 after eruption. This preliminary estimate is somewhat earlier than the 5.9±0.5 days measured in 2014 (ATel #6558, Henze et al. 2015), the 5.7±0.5 days seen in 2015 (ATel #7984, Darnley & Henze et al. 2016), and the 5.8 days observed for the peculiar 2016 eruption (ATel #9872). This might suggest an earlier eruption date, which we are currently working on constraining more accurately.In addition, the nova is still detected as an UV source but its magnitude has declined significantly to uvw2 = 19.3±0.1 mag (cf. ATel #11121). Our preliminary magnitudes use the UVOT photometric system (Poole et al. 2008, Breeveld et al. 2011) and have not been corrected for extinction.
We report additional multicolor photometry of the 2017 outburst of the remarkable recurrent nova M31N 2008-12a (ATels #11116, #11117, #11118, #11121, #11124, #11125, #11126, #11130, see Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b for comprehensive multi-wavelength light curves of previous eruptions).
The magnitudes and upper limits for the nova are given in the table below.Date UT Exp. time Filter Magnitude Site 2017 Dec 31.384 120sec (60s x 2) none > 19.0 Itagaki Observatory (Okayama station), Japan (*1) 2018 Jan 01.4996 60sec none 18.6 Miyaki-Argenteus Observatory, Japan (*2) 2018 Jan 01.5186 60sec none 18.7 Miyaki-Argenteus Observatory, Japan 2018 Jan 01.529 360sec (60sec x 6) none 18.7 Itagaki Observatory (Okayama station), Japan 2018 Jan 02.127 5520sec (120sec x 46) L 19.14 +/- 0.09 New Mexico Skies, USA (*3) 2018 Jan 02.214 4500sec (180sec x 25) L 19.35 +/- 0.09 Sierra Remote Observatory, USA (*4) 2018 Jan 02.4014 60sec none > 19.4 Miyaki-Argenteus Observatory, Japan 2018 Jan 02.403 1800sec (30sec x 60) g 19.90 +/- 0.14 Okayama Astrophysical Observatory, Japan (*5) 2018 Jan 02.403 1800sec (30sec x 60) r 19.36 +/- 0.08 Okayama Astrophysical Observatory, Japan 2018 Jan 02.403 1800sec (30sec x 60) z 19.50 +/- 0.14 Okayama Astrophysical Observatory, Japan 2018 Jan 03.125 5400sec (180sec x 30) L 20.12 +/- 0.15 New Mexico Skies, USA 2018 Jan 03.3979 60sec none > 20.0 Miyaki-Argenteus Observatory, Japan 2018 Jan 03.507 1800sec (30sec x 60) g 20.72 +/- 0.16 Okayama Astrophysical Observatory, Japan 2018 Jan 03.507 1800sec (30sec x 60) r 20.29 +/- 0.10 Okayama Astrophysical Observatory, Japan 2018 Jan 03.507 1800sec (30sec x 60) z > 20.5 Okayama Astrophysical Observatory, Japan Filter ``L'' magnitudes are obtained from the observations with a luminescent (IR cut) filter. Telescopes and instruments:
The last ATel I have seen regarding the eruption of the remarkable recurrent nova M31N-2008-12a. It shows how the fading of the Nova quickly after outburst on 31st of December 2017. You can find it at this LINK8.
So the remarkable Recurrent Nova M31N 2008-12a went into eruption again for the tenth year and shows this recurrent nova is indeed growing closer to the Chandrasekhar limit of 1.4 solar masses and will then either erupt into a Type Ia Supernova or collapse directly into a neutron star depending on wither it is a Carbon Oxygen White Dwarf (Type Ia Supernova when it reaches the Chandrasekhar limit from accretion from the binary star) or a Neon Oxygen White Dwarf (collapses into a Neutron Star when it reaches the Chandrasekhar limit from accretion). Rather cool to see that this has happen for the last 10 years and probably has actually be occurring for million of years. Remember this may be repeated in March when our Sun interferes with imaging M31 from earth.
Found this and wanted to share. This is Lost in Light II and shows the impact of Light Pollution on the night sky. Glad the 3 darker locations are within 3 hours of my home!
I'll be adding my latest sketches and trip this week!
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.
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.
Orion Sirius Plossl 25mm 52o 10" f/4.6 = 47x 1.113o 5.436mm
Orion Sirius Plossl 17mm 52o 10" f/4.6 = 69x 0.756o 3.696mm
Orion Sirius Plossl 12.5mm 52o 10" f/4.6 = 93x 0.556o 2.718mm
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.
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!