A New Star in the Sky?
You may have heard the news that there is a ‘new’ star that is becoming visible in the sky these days: so what is this all about? let’s find out.
On June 12th, the ASAS-SN (All-Sky Automated Survey for Supernovae) detected a new stellar object in the constellation Lupus, the Wolf. Now, Lupus is not one of the best-known constellations by non aficionados and for good reason: it is usually found very low on the horizon, especially at northern latitudes. Luckily, here in the Canary Islands, at meridian crossing (the highest point it reaches in the sky every night as the Earth keeps rotating, which coincides with the south meridian) it gets to a whopping 20º above the horizon, so it is clearly visible.
The newly discovered stellar object was later officially named V462 Lupi and classified as a nova based on the sudden increase in brightness and its spectral type.
So, what is a nova? Glad you asked…
The word ‘nova’ comes from Latin and it means ‘new’ because when ancient astronomers saw these objects in the sky appearing out of nowhere, they thought they were new stars just being born. We now know it is not the case, because it is a more complex phenomenon actually involving two stars. Let me explain: very frequently, stars are arranged in multiple systems, the most common being binary systems, with two stars orbiting around one another in a cosmic dance. When a white dwarf (what is left of a star the size of the Sun after it runs out of fuel) orbits a bigger star such as a red giant (a star reaching the end of its life), it often ‘steals’ material from its companion until it reaches size, temperature and pressure that ignites a thermonuclear runaway. This explosion is often visible to the naked eye or is captured by telescopes and appears like a new star has popped up, but it usually fades away after a few days or weeks when the blast is over. Over time, the white dwarf recharges and experiences another explosion in a cyclical fashion so the star does not get destroyed, at least completely. For this reason, astronomers classify novae as ‘classical’ if they erupt only once in human lifetime, or ‘recurrent’ if they can be observed to blast multiple times.
Now, do not get confused because there are other stellar explosions called supernovae or hypernovae, but these are different because they involve the complete destruction of the star, which is not the case with novae. We will have a separate post on the different types of supernovae in the near future, so stay tuned!
Getting back to our ‘new’ star, V462 Lupi has been classified as a classical nova, so chances are that we will not be able to see it blow up again within our lifetime (mine at least!), so take the opportunity and join our sunset and stargazing tours because we are able to see it right now.
If you want to follow the course of this event, go to this website: https://apps.aavso.org/v2/data/search/photometry/ and type the name of the star (V462 Lup) to see how bright it is: at the time of writing this post, its magnitude is 6, which is naked-eye visible (the magnitude limit of stars visible without gear is 8, and remember that higher numbers correspond to dimmer stars, whereas brigther stars have lower numbers).
Finally, most astrophiles have been on the edge of their seats for the past year or so because there is another nova event predicted to occur this year (T-Corona Borealis), which is a recurrent nova estimated to erupt every 80 years, but so far it has not gone bang… keep your eyes open and you might be the first one to see it happen!
Written by Dani
