10 interesting stars in the Milky Way
Someone once said to me that, if the Milky Way was New York, the stars we are able to
see with our naked eye would be the equivalent of a courtyard.
Our galaxy host billions and billions of stars and it is counted that, for spiral galaxies,
the equivalent of 3 solar star masses are born per year.
Today we want to take a look at the most interesting stars in the Milky Way!
1) Tabby's Star ( KIC 8462852 )
Officially named KIC 8462852, the star is 1,200 light-years away in the constellation
Cygnus and is about 1.4 times the mass of the Sun.
What intrigued astronomers about this star is that a transiting object caused it to dip
in light by as much as 20 per cent.
Now, usually, planets are responsible for some dips in the light when they pass in front
of the star, but 20 per cent was too much.
That object had to be something far, far bigger than a planet
Someone proposed weird explanations to that dip in light.
Explanation included a swarm of comets or—as a last resort—aliens.
The idea was that something causing that deep transit might be an artificial structure,
including a theorized "Dyson Swarm" of object harnessing power from the star.
Of course, this was not the case.
There is no alien civilization in front of Tabby's star.
In fact, subsequent observations have likely ruled out anything artificial.
Scientist thinks that a debris field of dust is responsible for the large dip in luminosity,
though there are various arguments as to the nature of the dust.
Anyway, the interesting fact here is that astronomers haven't witnessed anything like
the original detection since, though a series of observations recently detected five per
cent dips in light, which is much lesser than 20 per cent, but still far too large to be
a planet!
2) Mira Mira is not a single star.
It is actually a star system, a binary system, with a large pulsating red giant.
Mira A is the red giant, and Mira B is a much smaller white dwarf.
They are companions.
To the naked eye, Mira A is a variable star that essentially disappears and then reappears
almost every 11 months.
What makes Mira so interesting?
What’s going on in the system is that Mira A, the red giant, is shedding material into
space, and some of this material then accretes around Mira B.
This spreading of mass leads to the creation of two interesting phenomena in the system:
first, the system itself is shedding material into the interstellar medium.
This gives to Mira the superficial appearance of a giant comet, though the trailing material
stretches for light years!
(That is much greater than that of a comet’s tail.)
The second phenomenon is that there seems to be a protoplanetary disk formed around
Mira B from the ejected material from the red giant.
This is strange because protoplanetary disks are typically found around young stars rather
than dead white dwarfs.
This could mean that new planets are forming around a dead star, something not known to
happen before was discovered this system!
We just have to see what the next studies will suggest!
3) SAO 206462
We have just seen that Mira resemble a comet.
What if I told you there is a star that...looks superficially like a spiral galaxy?
In fact, it is a trait of SAO 206462.
This is a very young star surrounded by a protoplanetary disk - which is not unusual
for young stars still forming planets - but what’s unusual here is really the structure
of the disk.
It is arranged in a spiral-arms shape.
This star is relatively close to us, and its protoplanetary disc itself is huge: about
twice the size of the orbit of Pluto.
Scientists think that spiral structure seems to be due to recently formed planets within
the disk, being arranged in such a way as to shepherd and shape the disk into spiral
arms through gravity.
In this system, planets are still forming!
It's a newborn star system!
Once the planet will be formed, the spiral structure and indeed the visible disk will
probably disappear!
4) BPM 37093
No, it is not referred to a song's tempo.
BPM 37093 located in the constellation of Centaurus, BPM 37093 is about 50 light-years
from Earth.
This star was originally thought to be a white dwarf, but it was later found to be incredibly
dense.
It has a little bit more mass than our Sun but, it's way denser, with all the mass compacted
down to about a third of the size of the Earth, making it effectively a crystallized star.
White dwarfs in general are believed to be composed of carbon and oxygen, and a prediction
from the 1960s said that cooling white dwarfs should begin to crystallize.
If we found a pulsating variable white dwarf star, we could test our predictions: BPM 37093
is interesting because it allowed us just to do so!
So we tested our crystallization concept, and guess what?...
It turned out to be correct!
In the case of BPM 37093, it was found to be as much as 90 per cent crystallized, though
estimates of this vary.
So when you start subjecting carbon to high pressure and it begins to crystallize, you
get diamond or something like it.
It could be said that this white dwarf - at least at some depth - essentially turns into
a big big big diamond.
Would you still call it a star?
5) MY Camelopardalis
A study of the binary system MY Camelopardalis shows that the most massive stars are made
up of the merging of smaller stars, as predicted by theoretical models: smaller to bigger.
Most of the stars in the Milky Way formed in binary or multiple systems.
MY Camelopardalis (MY Cam), consists of two of the most massive objects known.
In fact, its components, two stars of spectral type O, that is blue, very hot and bright,
with masses respectively equal to 38 and 32 times the mass of the Sun, are still in the
main sequence and are very close.
Their orbital period lasts less than 1.2 days and represents the shortest so far measured
in this class of binary systems.
This suggests that the two components virtually originated as they are today: the two stars
were almost in contact when they formed.
The fate of the binary system will be the fusion, that is the merging, of the two components,
before the two stars have time to follow their own evolution, which will lead to the formation
of a single object with a mass greater than 60 solar masses.
These results demonstrate the validity of some theoretical models according to which
more massive stars are formed from the merging of less massive stars.
6) Vega
We live with the concept that the poles of a planet are usually colder than the equator.
Can we say the same thing about stars?
Well, telescopic observations in 2006 revealed that Vega is whipping around so quickly that
its poles are several thousand degrees warmer than its equator.
The star, which rotates every 12.5 hours, is at 90 per cent of its critical rotation
speed, or the velocity at which the object would tear itself apart.
Another interesting thing about Vega is that astronomers discovered an asteroid belt surrounding
it, suggesting the chance for planets within the midst.
The layout suggests that there are two areas: an outer region with icy asteroids and a region
closer to the star, where warmer space rocks reside.
Vega is by far one of the most known stars of our Milky Way because astronomers use it
as a reference star for luminosities measures!
7) HD 101065
Within the Centaurus constellation is hiding a southern sky constellation, just beyond
what our eyes can see.
And it is a truly weird star.
It's called HD 101065.
It is about four times the mass of the sun and what makes it so special is that HD 101065
Star is cooking up the kinds of elements we don't normally see in stars—including uranium.
(The Sun, like many stars, doesn't typically fuse anything heavier than nickel, which is
number 28 on the periodic table.)
Jason Wright, an astrophysicist, called the star his "favourite astrophysical enigma"
in a blog post.
In fact, most of these elements have short half-lives, so something may be replenishing
them.
Searches for a small pulsar have failed, but it could be that the star cooked up super
heavy elements that are decaying into ones never found on Earth.
8) HD 140283
The interesting fact about HD 140283 is its age.
The universe is 13.8 billion years old.
HD 140283, by all appearances, is 14.4 billion years old.
That is a problem with cosmology.
The age estimate is based on its composition, brightness, and distance (the star is 190
light-years away.)
Well, it has to be said that the minimum estimated age is 13.2 billion years, and the margin
of error of the 14.4 billion year estimate probably places it comfortably—but barely—within
the age of the universe.
But we need more observations, in order to increase our precision.
Anyway, even if it's not old as the universe, it was born right after the Big Bang!
The study of this star could lead us to a better understanding of the first moments
in the life of our Universe!
9) CP 1919
In 1967, a radio signal was detected by Jocelyn Bell and Antony Hewish.
The signal had a 1.3 second period and 0.04-second pulse width.
It originated at celestial coordinates 19h 19m right ascension, +21° declination.
Due to its almost perfect regularity, it was at first assumed to be spurious noise, but
this hypothesis was promptly discarded.
The discoverers jokingly named it “little green men 1” (LGM-1), considering that it
may have originated from an extraterrestrial civilization, but Bell soon ruled out extraterrestrial
life as a source after discovering a similar signal from another part of the sky.
The original signal turned out to be radio emissions from the pulsar CP 1919 and was
the first one recognized as such.
Before the nature of the signal was determined, the researchers considered the possibility
of extraterrestrial life: “We did not really believe that we had picked
up signals from another civilization, but obviously the idea had crossed our minds and
we had no proof that it was an entirely natural radio emission.
It is an interesting problem – if one thinks one may have detected life elsewhere in the
universe[,] how does one announce the results responsibly?
Who does one tell first?”
This pulsar became famous in the pop culture as the English post-punk band Joy Division
used an image of CP 1919's radio pulses for the cover art on their 1979 debut album, "Unknown
Pleasures".
Have you ever seen that cover?
10) SUN
This is the star everybody knows.
Why is it important?
Well, “simply” because the Sun is the only star we know that host life, so far!
The Sun is the star at the centre of the Solar System.
It is by far the most important source of energy for life here on Earth.
Its diameter is about 1.39 million kilometres (864,000 miles).
The Sun is a G-type main-sequence star (G2V) based on its spectral class.
The enormous effect of the Sun on Earth has been recognized since prehistoric times.
The Sun has been regarded by some cultures as a deity.
The synodic rotation of Earth and its orbit around the Sun are the basis of solar calendars,
one of which is the Gregorian calendar, the predominant calendar in use today.
We are glad to live in its neighbourhood!
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