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1/07/2018

Recurrent Nova M31N 2008-12a 2017 Eruption





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:

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.
A January 1st, 2018, ATel reports this LINK3 . 

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 
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. 

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. 

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 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. 

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. 20142015a2015b; Darnley et al. 201420152016) 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 
 
This ATel from January 4th, 2018 shows more optical photometric observations of the 2017 eruption.  You can find it at this LINK6

The January 5th, 2018 report found in this ATel LINK7 has some good information on it. It reports:

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. (201420152016) and Henze et al. (20142015a2015b, 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.

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. 

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. 201420152016 and Henze et al. 20142015a2015b 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.





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