The constellation Herdsman, with its star Arturo
Have you ever heard of the star Arturo and the constellation Bootes?
It is a boreal constellation, with a characteristic shape reminiscent of a long kite, on the tip of which stands a wonderful orange star, very bright and whose name everyone wants to know sooner or later.
Bootes is always well recognizable with Arturo, easily reached by imaginatively extending the arch formed by the three stars of the Big Dipper (those that form the handle): at 9 p.m., it rises to the North-East in the last decade of February, culminating in the South, high on the horizon, at the end of June, while it is low on the horizon, to the North-West in mid-October.
A thousand times I've said it and a thousand times the hilarity of those present was immediately unleashed, until I pointed out that the name Arturo comes from a Greek word meaning "guardian of the Bear".
The constellation contains as many as 9 stars closer than 60 light years (including the star Arcturus), a few medium-sized stars, and very few Deep Sky objects.
The name, history and myth of Herdsman
His name means 'redneck' or 'peasant', and he was the keeper of the seven oxen (actually the seven stars of the constellation Canes Venatici) that pulled the Big Dipper, but it's likely that his name, Boote, comes from a transposition of the Sumerian word riv-but-san, or "the man who drives the Big Dipper".
It is no coincidence that the Big Dipper is located north of Bootes, and the 'kite' shape of the constellation Bifolco seems to indicate the point to the north.
Mythology also assigns other versions: Arcade, son that Zeus had from his lover Callisto, was raised by his maternal grandfather Lycaon. One day Zeus stopped to eat at Lycaon's, who, to make sure he had the true head of the gods in front of him, served his son Arcade at his table. Zeus noticed this and, seized by anger, turned Lycaon into a wolf and resurrected his son. In the meantime, Zeus turned Callisto into a bear, to make her escape from the wrath of his wife Hera. Growing up, Arcade runs into the bear, but obviously not recognizing her mother, he starts hunting her until the bear takes shelter in a sacred place. As desecrators of the sacred place, Callisto and Arcade would be condemned to death and Zeus, to avoid this fate, sent them to heaven: Callisto was the Big Bear while Arcade was the farmer.
Others see the redneck keep the two hunting dogs Chara and Asterion on a leash to stop them from chasing the Bear through the sky.
Another legend identifies Boote with the Athenian Icarius, father of Erigon. Dionysus (the Bacchus of Roman mythology) taught Icarius the secret recipe for making wine. Some time later, it happened that Icarius gave wine to some wayfarers, who got drunk; thinking they had been poisoned, in the grip of intoxication, they killed Icarius and buried his body.
Helped by her father's dog, Maena, Erigone searched for her parent's burial and when he found her she was so distressed that she hanged herself.
Then Zeus (or in other versions Dionysus) pitilessly placed it in the constellation of the Virgin; Icarius became instead Boote and Maera was Raccoon in the Lesser Dog or one of the dogs of the neighbouring constellation of the Hunting Dogs.
Herdsman main stars
In this constellation there are several stars with a name:
- Arturo (α Boo): from the Greek, the guardian of the bear
- Nekkar (β Boo): the excavator
- Seginus (γ Boo): Latinization of Cygnus, son of Neptune
- Thiba (δ Boo): the lupe
- Izar or Pulcherrima (ε Boo): the veil or the most beautiful
- Muphrid (η Boo): lonely star
- Asellus I, II and III (θ, ι and κ Boo): donkey
- Aulad Althiba (λ Boo): fox cubs
- Alkalurops (μ1 Boo): the herdsman's stick
- Ceginus (φ Boo): latinization of Cygnus, son of Neptune
- Aulad Alnathlat (ψ Boo): the puppies
- Merga (38 Boo): from Latin, the hoe
As always, we see the representation of Bootes according to the Uranometria
according to astronomer Hevelius
and according to what was conceived by the creators of Stellarium
in all three cases it is a bucolic figure, a herdsman, more or less old, holding a stick.
Deep Sky Objects
There aren't many Deep Sky objects in this constellation. I chose two. The first one is a very nice globular cluster, NGC 5466, visible even with amateur telescopes
the globular cluster NGC 5466
while the other object is a dwarf galaxy, Bootes I, satellite galaxy of the Milky Way.
Many nearby stars
Pocanzi I wrote that there are 9 stars in Bootes within a 60 light-years radius of the Sun. Let's see them.
We start from the nearest one, Gliese 526, a little less than 18 to the Sun, that seen from this star appears as a small star of magnitude 3.5 within our constellation of the Whale, while from the vicinity of the double star ξ Boo, our star appears already of fourth magnitude, in the company of Sirius and α Centauri.
More or less in the same zone of sky appears the Sun seen by Arturo, by η Boo (Muphrid) and by HIP 72848, all three placed at a distance of 37-38 al: this time we also find other famous stars like Diphda (of the Whale) and Fomalhaut, of the Southern Fish. The reckoning is right: we must always think that all the stars are placed in a three-dimensional space and normally situations of this kind are generated, as we have seen many times and as I have tried to synthesize in this diagram, absolutely not in scale. In this case we have in fact that these three stars are also close to each other in our sky: between them (thanks to Celestia) there are at most 5 light years away. It should be clear that the Sun projects itself in the same area of the sky if seen from these stars close to us and physically close to each other. If we take a good look at the three photos of the Sun seen from the group of three stars, we can also find ξ Boo, which in fact is physically along the path between us and the group of stars!
I know: the reasoning is quite twisted and the situation as well... Just think about it for a moment to come to the conclusion that Astronomy is, yes, a beautiful Science, but like all Sciences it can be, rightly, also difficult! I conclude by pointing out that in the picture taken by τ Boo we find (obviously) Arturo, this time next to the old acquaintance Altair: in the diagram of before, τ Boo was in fact beyond the now famous trio of stars. But just τ Boo is a nice double: I went to my Taubooani friends to see this pair of stars from the distance of 50 UA and taste the difference in color between a class F7 and a class M2 star. Quite unusual characteristic of my friends, who live on a planet around these two stars, is that they all have one blue eye and the other reddish: you watch when you say the case...
Finally, looking at the photos taken by 44, θ and σ Boo, we see the Sun practically in another area of the sky with Sirius, Raccoon, Achernar and Acamar. Enough... Let's move on to other stars...
Some stars (not very big)
As already anticipated, the constellation of Bootes doesn't present excessively large stars: now accustomed to supergiant monsters 1000 times the Sun, it doesn't affect us anymore to find stars larger than 100, but also 87, 69 and 55 times our Sun, respectively 34, ν1, 13 and ε Boo.
Precisely because 130 times the diameter of the Sun gives the star 34 Boo the status of red giant (it's M3 class), I couldn't help but visit my friends Thirty-four, who are also giants, but above all they're very attached to money, as you can tell from their name.
But woe betide them, they look down on you with their five eyes.
Izar and Pulcherrima
Among the peculiarities of Bootes, we have that the star Izar ( ε Boo ), actually, is a beautiful double star with a great chromatic contrast between the two components. It is visible with not really small telescopes, but always of amateur level. Izar (of 2.4, and spectral class K0) is of yellow-orange colour, while the secondary one (of fifth , class A2) is of a beautiful blue colour. Given these premises it should come as no surprise that this star was immediately baptized by the astronomers Pulcherrima, the most beautiful.