Neptune-Sized Planet Found Orbiting a Dead White Dwarf Star. Here’s the Crazy Part, the Planet is 4 Times Bigger Than the Star

Astronomers have discovered a large Neptune-sized planet orbiting a white dwarf star. The planet is four times bigger than the star, and the white dwarf appears to be slowly destroying the planet: the heat from the white dwarf is evaporating material from the planet’s atmosphere, forming a comet-like tail.

Continue reading “Neptune-Sized Planet Found Orbiting a Dead White Dwarf Star. Here’s the Crazy Part, the Planet is 4 Times Bigger Than the Star”

Weekly Space Hangout: October 7, 2019 – Marina Kounkel talks Stars and How They Form

Hosts:
Fraser Cain (universetoday.com / @fcain)
Sondy Springmann (@sondy)
Beth Johnson (@planetarypan)
Michael Rodruck (@michaelrodruck)

This week we welcome Dr. Marina Kounkel, a postdoctoral scholar in the Physics and Astronomy Department at the Western Washington University. Her research focuses on observing the dynamics of young stars.

Continue reading “Weekly Space Hangout: October 7, 2019 – Marina Kounkel talks Stars and How They Form”

Traces of One of the Oldest Stars in the Universe Found Inside Another Star

Despite all we know about the formation and evolution of the Universe, the very early days are still kind of mysterious. With our knowledge of physics we can shed some light on the nature of the earliest stars, even though they’re almost certainly long gone.

Now a new discovery is confirming what scientists think they know about the early Universe, by shedding light on a star that’s still shining.

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Eta Carinae is Getting Brighter Because a Dust Cloud was Blocking our View

Eta Carinae, one of the most massive stars known. Image credit: NASA

In addition to being one of the most beautiful and frequently photographed objects in the night sky, Eta Carinae also has also had the honor of being one of the sky’s most luminous stars for over a century and a half. In addition, it has been a scientific curiosity since its giant ejected nebula (Homunculus) contains information about its parent star.

It is therefore sad news that within a decade or so, we will no longer be able to see the Homunculus nebula clearly. That was the conclusion reached in a new study by an international team of researchers. According to their findings, the nebula will be obscured by the growing brightness of Eta Carinae itself, which will be ten times brighter by about 2036.

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Astronomy Cast Ep. 513: Stellar Fusion

The Sun. It’s a big ball of fire, right? Apparently not. In fact, what’s going on inside of the Sun took us some time and knowledge of physics to finally figure out: stellar fusion. Let’s talk about the different kinds of fusion, and how we’re trying to adapt it to generate power here on Earth.

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Scientists are Using Artificial Intelligence to See Inside Stars Using Sound Waves

NASA's Solar Dynamics Observatory has captured images of a growing dark region on the surface of the Sun. Called a coronal hole, it produces high-speed solar winds that can disrupt satellite communications. Image: Solar Dynamics Observatory / NASA

How in the world could you possibly look inside a star? You could break out the scalpels and other tools of the surgical trade, but good luck getting within a few million kilometers of the surface before your skin melts off. The stars of our universe hide their secrets very well, but astronomers can outmatch their cleverness and have found ways to peer into their hearts using, of all things, sound waves. Continue reading “Scientists are Using Artificial Intelligence to See Inside Stars Using Sound Waves”

How Much Stuff is in a Light Year?

The Milky Way is an extremely big place. Measured from end to end, our galaxy in an estimated 100,000 to 180,000 light years (31,000 – 55,000 parsecs) in diameter. And it is extremely well-populated, with an estimated 100 to 400 million stars contained within. And according to recent estimates, it is believed that there are as many as 100 billion planets in the Milky Way. And our galaxy is merely one of trillions within the Universe.

So if we were to break it down, just how much matter would we find out there? Estimating how much there is overall would involve some serious math and incredible figures. But what about a single light year? As the most commonly-used unit for measuring the distances between stars and galaxies, determining how much stuff can be found within a single light year (on average) is a good way to get an idea of how stuff is out there.

Light Year:

Even though the name is a little confusing, you probably already know that a light year is the distance that light travels in the space of a year. Given that the speed of light has been measured to 299,792, 458 m/s (1080 million km/h; 671 million mph), the distance light travels in a single year is quite immense. All told, a single light year works out to 9,460,730,472,580.8 kilometers (5,878,625,373,183.6 mi).

Diagram showing the distance light travels between the Sun and the Earth. Credit: Wikipedia Commons/Brews ohare

So to determine how much stuff is in a light year, we need to take that distance and turn it into a cube, with each side measuring one light year in length. Imagine that giant volume of space (a little challenging for some of us to get our heads around) and imagine just how much “stuff” would be in there. And not just “stuff”, in the sense of dust, gas, stars or planets, either. How much nothing is in there, as in, the empty vacuum of space?

There is an answer, but it all depends on where you put your giant cube. Measure it at the core of the galaxy, and there are stars buzzing around all over the place. Perhaps in the heart of a globular cluster? In a star forming nebula? Or maybe out in the suburbs of the Milky Way? There’s also great voids that exist between galaxies, where there’s almost nothing.

Density of the Milky Way:

There’s no getting around the math in this one. First, let’s figure out an average density for the Milky Way and then go from there. Its about 100,000 to 180,000 light-years across and 1000 light-years thick. According to my buddy and famed astronomer Phil Plait (of Bad Astronomy), the total volume of the Milky Way is about 8 trillion cubic light-years.

And the total mass of the Milky Way is 6 x 1042 kilograms (that’s 6,000 trillion trillion trillion metric tons or 6,610 trillion trillion trillion US tons). Divide those together and you get 8 x 1029 kilograms (800 trillion trillion metric tons or 881.85 trillion trillion US tons) per light year. That’s an 8 followed by 29 zeros. This sounds like a lot, but its actually the equivalent of 0.4 Solar Masses – 40% of the mass of our Sun.

This image from the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile, shows the bright star cluster NGC 6520 and its neighbour, the strangely shaped dark cloud Barnard 86. This cosmic pair is set against millions of glowing stars from the brightest part of the Milky Way — a region so dense with stars that barely any dark sky is seen across the picture.
Millions of glowing stars from the brightest part of the Milky Way — a region so dense with stars that barely any dark sky is seen across the picture. Credit: ESO

In other words, on average, across the Milky Way, there’s about 40% the mass of the Sun in every cubic light year. But in an average cubic meter, there’s only about 950 attograms, which is almost one femtogram (a quadrillionth of a gram of matter), which is pretty close to nothing. Compare this to air, which has more than a kilogram of mass per cubic meter.

To be fair, in the densest regions of the Milky Way – like inside globular clusters – you can get densities of stars with 100, or even 1000 times greater than our region of the galaxy. Stars can get as close together as the radius of the Solar System. But out in the vast interstellar gulfs between stars, the density drops significantly. There are only a few hundred individual atoms per cubic meter in interstellar space.

And in the intergalactic voids; the gulfs between galaxies, there are just a handful of atoms per meter. Like it or not, much of the Universe is pretty close to being empty space, with just trace amounts of dust or gas particles to be found between all the stars, galaxies, clusters and super clusters.

So how much stuff is there in a light year? It all depends on where you look, but if you spread all the matter around by shaking the Universe up like a snow globe, the answer is very close to nothing.

We have written many interesting articles about the Milky Way Galaxy here at Universe Today. Here’s 10 Interesting Facts About the Milky Way, How Big is the Milky Way?, How Many Stars are There in the Milky Way?, Where is the Earth Located in the Milky Way?, How Far is a Light Year?, and How Far Does Light Travel in a Year?

For more information, check out How many teaspoons are there in a cubic light year? at HowStuffWorks

Astronomy Cast also has a good episode on the subject. Here’s Episode 99: The Milky Way

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