Monitoring for V1280 Sco = N Sco 2007

V1280 Scorpii = Nova Scorpii 2007 No. 1 (NB)
https://www.aavso.org/vsx/index.php?view=detail.top&oid=142126

After a rapid brightening had occurred in April 2018, the nova faded rapidly on 14–15 September.
Previous fadings occurred in mid-September 2017 and late March 2018.
Complete ASAS-SN Sky Patrol (Shappee et al. 2014ApJ...788...48S and Kochanek et al. 2017PASP..129j4502K) light curve:
https://asas-sn.osu.edu/light_curves/53dde434-4bc8-4e65-8ce0-bf49432415…

Recent AAVSO observations: https://www.aavso.org/apps/webobs/results/?star=V1280+Sco

Clear skies,
Patrick

I just added the latest obs as of this morning. It looks like the observing time (at least from the iTelescope SSO faciltity in Australia) is about another 3 weeks. So I'll image as long as I can. This object has decreased 1 mag V and 0.866 mag B between 9/11/2018 and 9/30/2018.

Dr. Fred Walter (Stony Brook University) posted an update in the Novae forum on the extremely interesting nova V1280 Sco (N Sco 2007). Here is the link to his post:

https://www.aavso.org/v1280-sco-update

The original campaign (organized at his request) on this nova took place in 2018 (AAVSO Alert Notice 634).

Dr. Walter expresses his thanks to all observers who have contributed data, and asks for the observations please to continue!

Good observing,

Elizabeth

HI,

I have observed V1280 Sco for the past nearly 3 months every clear night. Observing season is ending and the star is at airmass 2.6 already. Should I continue observations as long as it is feasible or stop. Should observations be restarted as soon as the star is visible in the morning sky again at high airmass? I did so for V1047 Cen another interesting star (Fred Walter is also in the distribution list ).

Josch

Thanks to all of you who have added V1280 Sco to your observing list.
Please keep the data coming!

I refer you back to my update of 7/9/19 (https://www.aavso.org/v1280-sco-update) for the background on this star. Basically, this nova, now over 12 years past peak, hasn't decided what to do. The star has
stayed some 7 mag above quiescence, and 7 mag below peak brightness.

The most recent photometry (since 1 July 2019) is shown in Figure 1. The figure includes AAVSO and ASAS-SN (g-band) data, along with near-IR data from Andicam in July 2019. As you can see, the star continues to dither by about 1 magnitude in all bands, with 11.3>V>10.3).

Please continue to observe this star. I have not been pushing the campaign this year because CTIO and SMARTS/Chiron have been closed since March due to the serious COVID-19 outbreak in Chile, and so I am not obtaining any spectroscopy this season. But also the star is not doing much.

The science, as I outlined earlier, is that as the star fades the spectrum changes from a cool (T ~ 8000 K) dense optically-thick gas to include a number of hot (T > 50,000 K) forbidden lines that can form only at low densities. My hypothesis is that the gaps in the optically-thick shell permit us to see into the hot, low density material that surrounds the still-hot white dwarf star. The spectral changes with brightness are shown in Figure 2.

Eventually the star must fade back to quiescence (R>19). At present the luminosity is over 500 times that of the pre-nova system. The source of the luminosity is unknown, and unlikely to be permanent, though it has been present for some 12 years.

The Campaign
Please continue to get occasional observations during this observing season (through about October 2020). It will probably continue to dither, but if it fades much below V~11.3, or stays near V=11.3 for a few days, then something interesting may be happening. Please upload your data, and drop me a note (post to the forum).

I hope to resume the spectroscopic monitoring in 2021. At that point frequent observations, with a daily cadence where possible, would be useful. BVR_cI_c band photometry will be most useful. Note that in its current state, V1280 Sco can change by a magnitude in a few days. The magnitude variations are similar in all bands, so multi-color monitoring is not required (but is desirable nonetheless) unless its behavior changes.

There is no guarantee that V1280 Sco will do anything spectacular anytime soon. But someday it will fade back to that oblivion from whence it came. How it does so will inform us of the external environments of novae, and of the energy sources in this particular system. Let is be watching when it does.

Figure Captions:
Figure 1: Photometry of V1280 Sco since 1 July 2019. Since the retirement of Andicam on 31 July 2019, the bulk of the data are from AAVSO observers, supplemented by g-band data from ASAS-SN. Variations are colorless. The magnitude of the variations is about 1 mag.

Figure 2: Brightness-related spectral variations in V1280 Sco. These spectra are from the SMARTS Chiron echelle spectrograph, at a resolution of 27,800. The colors are arbitrary. The continua are set at the V magnitude within half a day of when the spectra were obtained. I only show a small portion of the full (4080-8900 Angstrom) spectrum.
When bright (top spectra), the emission is dominated by a plethora of centrally-reversed singly-ionized iron (Fe II) lines. These lines are omni-present. The narrow emission line at 4713 Angstroms is neutral helium (He I). When the star is bright, there is an outflow - a stellar wind - evidenced by the dip below the continuum level on the blue (short wavelength) side of the He I line. When the star fades, strong emission of doubly ionized carbon (C III; 4645-4650 Angstroms) and ionized helium (He II) at 4686 Angstroms grow. The changes appear correlated with magnitude. At longer wavelengths other hot lines appear, including [O III], C IV, and [Fe VII].