Hello Space Fans and welcome to another edition of Space Fan News.
This week, ALMA is at it again.
Astronomers using the world's largest radio telescope the Atacama Large Millimeter/submillimeter
array (that's what ALMA stands for) have found the most massive star in the Milky Way Galaxy.
ALMA is composed of 66 high precision antennas located on the (oh man, I have no idea how
to pronounce this) Chajnantor plateau, which is 5000 meters high in northern Chile.
So while sitting high atop the Chajnantor plateau looking all high and mighty, astronomers
pointed ALMA towards the constellation Norma (The Carpenter's Square), yes that's a constellation,
and looked at the dark star forming cloud known as Spitzer Dark Cloud 335.579-0.292.
There, looking in the microwave region of the spectrum they found the most massive star
in our galaxy 11,000 light years away.
SDC335.579-0.292 was first discovered as an environment of dark, dense filaments of gas
from observations using the Spitzer Space Telescope and ESA's Herschel Space Observatory.
Now ALMA has looked at it with it's high sensitivity in detail at both the amount of dust and the
motion of the gas moving around within the dark cloud — and there they found a really
massive star being born.
The goal here was to observe how really massive stars form and these observations hit pay
dirt: they found the largest protostellar core ever seen in the Milky Way.
This core has over 500 times the mass of our Sun swirling around inside.
And the ALMA observations show that much more material is still flowing inwards and increasing
the mass still further.
This star formation region is forming many stars and the 500 solar mass core is the most
massive of several.
This material will eventually collapse to form a young star up to 100 times as massive
as our home star.
Only about one in ten thousand of all the stars in the Milky Way reach that kind of
mass.
Not only are these stars rare, but their birth is extremely rapid and their childhood is
short, so finding such a massive object so early in its evolution is really hard, making
this a spectacular.
Different theories exist as to how massive stars form but the team's findings lend weight
to the idea that the entire cloud core begins to collapse inwards, with material raining
in towards the center to form one or more massive stars.
Sounds good to me.
Next, astronomers using the Hubble Space Telescope have figured out the actual visible-light
color of a planet orbiting another star 63 light-years away.
If we could see this planet directly, it would look just like that famous 'pale blue dot'
picture of Earth taken from the Voyager 1 spacecraft back in 1990.
Unfortunately we can't do that yet so what they did instead was point Hubble's Imaging
Spectrograph at it to measure changes in the color of light from the system before, during,
and after the passage of the planet behind the parent star.
We got lucky here, this technique is possible because the planet's orbit happened to be
tilted edge-on as viewed from Earth; and because of that, it routinely passes in front of and
then behind the star.
Here's how they did it.
It's quite clever actually.
In order to measure what this planet would look like, the astronomers measured how much
light was reflected off the surface of the exoplanet known as HD 189733b — a property
known as albedo.
Now this planet is faint and close to its star.
To isolate the planet's light from this starlight, Hubble measured a small drop in light — about
one part in 10,000 — of the star's light when the planet went behind it, along with
a very tiny change in the color of the light, too.
As it moved behind the star the light become less bright in the blue, but not in the green
or the red.
This meant that the planet that went behind the star must be blue because light from was
missing in the blue, but not in the red when it was hidden.
The planet was contributing a tiny amount of blue light to the star's spectrum as it
passed in front.
So, it must be blue.
See?
Clever huh?
Now the Earth looks blue from space because the oceans absorb red and green wavelengths
more strongly than blue light.
In addition, the oceans reflect Earth's blue sky where the shorter blue wavelengths of
sunlight are selectively scattered by atmospheric oxygen and nitrogen molecules in a process
called Rayleigh scattering.
But that's not why this planet is blue, far from it.
HD 189733b was discovered in 2005.
It is only 2.9 million miles from its parent star, the planet is so close that it is gravitationally
"tidally locked" so that one side always faces the star and the other side is always dark.
In 2007 the Spitzer Space Telescope measured the infrared light, or heat, from the planet.
This observation produced one of the first-ever temperature maps of an exoplanet.
The map shows that the dayside and night-side temperatures differ by about 260 degrees Celsius.
This temperature difference would cause fierce winds to roar from the daytime to nighttime
side of the planet.
So why is this planet blue?
According to the spectra there are silicate particles laced in the high clouds of the
atmosphere.
Because the temperature is so high the silicate particles could condense and form very small
drops and they would scatter blue light more than red light.
So let's put all this together, here we have a planet with a daytime temperature of over
1,000 degrees Celsius, and it possibly rains glass — sideways mind you — in howling
7,000 kilometer per hour winds.
Just like downtown.
Well, that's it for this week Space Fans.
Thank you for watching and as always, Keep Looking Up!