But... what a star !
Today we can follow a very long maximum of this star (Omicron Ceti), more than 45 days with a magnitude better than +4, (tonight +3.2), and not fading yet. This maximum is far from usual. In the Latin language Mira means the « Marvelous ».
I spend some nice evenings with this interesting star. Of course I send my own magnitude visual estimations to the AAVSO but not only. Since David Fabricius (an amateur astronomer) in the year 1596, we are 2267 observers drawing the curve of this first ever variable.
Here’s the story.
- I found a nice beach of the Artignosc lake to paint this watercolor. We can see the bridge over the river and the moon light near the horizon, what photographers can’t do; I take the moon off the sky to show only the stars. As an auto-portrait, you can also see the sketcher. I show you the direction of Mira.
- In my little observatory I used my refractor, 152mm F/D=8 connected with a « star analyzer » 100 and the associated 3.8° prism. This is just a “visual” spectrum also watercolor made. To do this I sketch the rainbow line in black and white and I point out the visible absorptions and emissions lines. Anyway I can see some interesting lines as those of TiO and ZrO plus the H gamma emission one.
- The funnier think I did then, I use as a reference the sketch done by Camille Flammarion, a famous French astronomer. This sketch was found in the « Les Etoiles » an old book (1882) that I have in my collection.
Mira is moving quite quickly in the sky (0.238" per year). The companion star of Mira is not a secondary star, much close (55 Ly) to us than Mira (300 Ly) but can be used as a reference because the speed of this companion is very low (0.011" per year). The first spot (1683) was plotted by Cassini. I just superpose my sketch of the field with the one of Flammarion, and the result gives only 10% error on the actual speed of Mira.
So here for this simple easy observation I used some astronomical subjects as, astronomical history, visual observation, spectroscopy, magnitude estimation, astronomical position, and of course, what we can do with a pencil and some colors, astro-sketching !
If weather permit, try to have a look at Mira tonight, same naked eye just the color is worth a visit.
Clear sky to you all
Michel
