Some of us still remember the years 2020 and 2021, when we had the opportunity to observe several bright novae in the northern sky one after another. In order of their discovery dates: V1361 Cyg, V1112 Per, V1405 Cas, V1674 Her, V606 Vul, with the recurrent nova RS Oph bringing this remarkable sequence to a climax.
In the summer of 2026, four readily observable novae appeared within a single season of the year. Their basic properties are summarised in Table 1. Figure 1 illustrates the diversity of their light curves. The traditional way of classifying novae according to the MMRD (Maximum Magnitude Rate of Decline) is illustrated by marking the T2 times — that is, the time required for the nova to fade by 2 magnitudes from maximum brightness. The limitations of this approach are evident in V1452 Tau, which reached maximum brightness three, or perhaps even four, times.
Table 1.
| Name | Position J2000.0 | Discovery | Peak brightness in V | Discoverer | Time T2 [d] |
|---|---|---|---|---|---|
| V488 Sge N Sge 2026 | 19 45 06.49 +18 22 42.1 | 2026-08-25 | 7.1 | New Milky Way (NMW) Survey | 3 |
| V8055 Sgr N Sgr 2026 No. 3 | 18 25 12.76 -22 25 29.3 | 2026-08-19 | 8.5 | New Milky Way (NMW) Survey | 7 |
| V1452 Tau N Tau 2026 | 05 21 07.63 +23 38 20.0 | 2026-08-06 | 8.9 | New Milky Way (NMW) Survey | 14 |
| V2104 Aql N Aql 2026 | 19 14 31.37 +12 03 53.6 | 2026-07-01 | 11.0 | Daily Cataclysmic Variable Alert Project | 14 |
According to recent studies, such as Aydi et al. (2024), even the traditional division into Fe II and He/N novae is outdated. These are simply different stages of spectroscopic evolution, some of which may have been missed in fast novae. Figure 2 supports this interpretation. It compares the spectra of our four novae at maximum brightness, T0, and at T2. The uniformity is somewhat disturbed by the continuum of Nova Aql 2026, which is strongly affected by interstellar extinction and reddening. Nevertheless, the evolution is essentially the same in all four objects. At maximum, we see P Cygni profiles with strong absorption in the Balmer lines. As the expanding envelope becomes more dilute, the absorption disappears and emission lines with higher excitation energies emerge, most notably Fe II lines. In the near future, we can also expect the appearance of forbidden lines characteristic of the nebular stage, when the density of the expanding gas has become extremely low.
Another interesting point is that the width of the emission lines, and therefore the expansion velocity, correlates with the rate at which the nova fades. The slower-declining Nova Tau 2026 and Nova Aql 2026 have evidently narrower Hα and Hβ emission lines.
This is, of course, a highly simplified view of the nova phenomenon. I can assure you that there are still many open questions, and observations are always useful — both photometric and spectroscopic. This is particularly true now, when, as usual, the interest of amateur observers tends to decline. During the later stages of a nova’s evolution, the changes are no longer as dramatic, but continued observations are still important.
A good example is the aforementioned V1405 Cas, which, two years after maximum, began to show quasi-periodic oscillations — a phenomenon that still lacks a generally accepted explanation.
Reference:
Revisiting the classics: on the evolutionary origin of the ‘Fe II’ and ‘He/N’ spectral classes of novae
Monthly Notices of the Royal Astronomical Society, Volume 527, Issue 3, pp.9303-9321.
Addendum 1:
At Piconcillo, we observe novae photometrically using CCD, CMOS, and visual techniques. Most recently, we also obtained our first spectrum. See Figure 3.
Addendum 2:
Anyone wishing to update Figure 1, showing the simultaneous evolution of the light curves of several novae, can use one of the tools publicly available at japysoft.bombol.space. In this particular case, select AAVSO Comparison from the menu, enter the objects, the T0 time, and the filter. The tool is, of course, useful not only for novae.
