Stars Archives

March 11, 2019March 11, 2019 by Paul M. Sutter

Massive Photons Could Explain Dark Matter, But Don’t

A computer simulation of the distribution of matter in the universe. Orange regions host galaxies; blue structures are gas and dark matter. Credit: TNG Collaboration

I’ll be the first to admit that we don’t understand dark matter. We do know for sure that something funny is going on at large scales in the universe (“large” here meaning at least as big as galaxies). In short, the numbers just aren’t adding up. For example, when we look at a galaxy and count up all the hot glowing bits like stars and gas and dust, we get a certain mass. When we use any other technique at all to measure the mass, we get a much higher number. So the natural conclusion is that not all the matter in the universe is all hot and glowy. Maybe some if it is, you know, dark.

But hold on. First we should check our math. Are we sure we’re not just getting some physics wrong?

February 2, 2019February 2, 2019 by Matt Williams

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 — Eta Carinae, one of the most massive stars known. 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.

January 15, 2019January 15, 2019 by Evan Gough

A New Technique to Figure Out How Old Stars Are

Embry-Riddle researchers used data captured by the Gaia satellite (shown here in an artist’s impression) to determine the ages of stars. Credit: European Space Agency – D. Ducros, 2013

Our understanding of the universe, and of the Milky Way, is built on an edifice of individual pieces of knowledge, all related to each other. But each of those pieces is only so accurate. The more accurate we can make one of the pieces of knowledge, the more accurate our understanding of the whole thing is.

The age of stars is one such piece. For years, astronomers have used a method of determining the age of stars that has a 10% to 20% margin of error. Now, a team of scientists from Embry-Riddle Aeronautical University has developed a new technique to determine the age of stars with a margin of error of only 3% to 5%.

January 15, 2019January 15, 2019 by Matt Williams

Bizarre Double Star System Flipped its Planetary Disk on its Side

This illustration shows a binary star surrounded by a thick disc of material in a polar orbit. Copyright and credit: University of Warwick/Mark Garlick

Astronomers theorize that when our Sun was still young, it was surrounded by a disc of dust and gas from which the planets eventually formed. It is further theorized that the majority of stars in our Universe are initially surrounded in this way by a “protoplanetary disk“, and that in roughly 30% of cases, these disks will go on to become a planet or system of planets.

Ordinarily, these disks are thought to orbit around the equatorial band (aka. the ecliptic) of a star or system of stars. However, new research conducted by an international group of scientists has discovered the first example of a binary star system where the orientation was flipped and the disk now orbits the stars around their poles (perpendicular to the ecliptic).

January 14, 2019January 14, 2019 by Matt Williams

Habitable Planets Around Red Dwarf Stars Might not get Enough Photons to Support Plant Life

Artist’s impression of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri. The double star Alpha Centauri AB is visible to the upper right of Proxima itself. Credit: ESO

In recent years, the number of extra-solar planets discovered around nearby M-type (red dwarf stars) has grown considerably. In many cases, these confirmed planets have been “Earth-like“, meaning that they are terrestrial (aka. rocky) and comparable in size to Earth. These finds have been especially exciting since red dwarf stars are the most common in the Universe – accounting for 85% of stars in the Milky Way alone.

Unfortunately, numerous studies have been conducted of late that indicate that these planets may not have the necessary conditions to support life. The latest comes from Harvard University, where postdoctoral researcher Manasvi Lingam and Professor Abraham Loeb demonstrate that planets around M-type stars may not get enough radiation from their stars for photosynthesis to occur.

December 31, 2018 by Paul M. Sutter

A Guide to Hunting Zombie Stars

R Aquarii is called a symbiotic star system because of their relationship. As the white dwarf draws in material from the Red Giant, it ejects some if it in weird looping patterns, seen in this Hubble image. Image Credit: By Judy Schmidt from USA - Symbiotic System R Aquarii, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=63473035

Apparently not all supernovas work. And when they fail, they leave behind a half-chewed remnant, still burning from leftover heat but otherwise lifeless: a zombie star. Astronomers aren’t sure how many of these should-be-dead creatures lurk in the interstellar depths, but with recent simulations scientists are making a list of their telltale signatures so that future surveys can potentially track them down.

Continue reading “A Guide to Hunting Zombie Stars”

December 6, 2018December 6, 2018 by Paul M. Sutter

Astronomers Count all the Photons in the Universe. Spoiler Alert: 4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 Photons

The NASA/ESA Hubble Space Telescope offers this delightful view of the crowded stellar encampment called Messier 68, a spherical, star-filled region of space known as a globular cluster. Mutual gravitational attraction amongst a cluster’s hundreds of thousands or even millions of stars keeps stellar members in check, allowing globular clusters to hang together for many billions of years. Astronomers can measure the ages of globular clusters by looking at the light of their constituent stars. The chemical elements leave signatures in this light, and the starlight reveals that globular clusters' stars typically contain fewer heavy elements, such as carbon, oxygen and iron, than stars like the Sun. Since successive generations of stars gradually create these elements through nuclear fusion, stars having fewer of them are relics of earlier epochs in the Universe. Indeed, the stars in globular clusters rank among the oldest on record, dating back more than 10 billion years. More than 150 of these objects surround our Milky Way galaxy. On a galactic scale, globular clusters are indeed not all that big. In Messier 68's case, its constituent stars span a volume of space with a diameter of little more than a hundred light-years. The disc of the Milky Way, on the other hand, extends over some 100 000 light-years or more. Messier 68 is located about 33 000 light-years from Earth in the constellation Hydra (The Female Water Snake). French astronomer Charles Messier notched the object as the sixty-eighth entry in his famous catalogue in 1780. Hubble added Messier 68 to its own impressive list of cosmic targets in this image using the Wide Field Camera of Hubble’s Advanced Camera for Surveys. The image, which combines visible and infrared light, has a field of view of approximately 3.4 by 3.4 arcminutes. Credit: Hubble/NASA/ESA

Imagine yourself in a boat on a great ocean, the water stretching to the distant horizon, with the faintest hints of land just beyond that. It’s morning, just before dawn, and a dense fog has settled along the coast. As the chill grips you on your early watch, you catch out of the corner of your eye a lighthouse, feebly flickering through the fog.

And – yes – there! Another lighthouse, closer, its light a little stronger. As you scan the horizon more lighthouses signal the dangers of the distant coast.
Continue reading “Astronomers Count all the Photons in the Universe. Spoiler Alert: 4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 Photons”

November 28, 2018 by Paul M. Sutter

We May Soon Be Able To See the First, Supergiant Stars in the Universe

An artist's illustration of the first stars to appear in the universe. Credit: N.R. Fuller, National Science Foundation

We need to talk about the dark ages. No, not those dark ages after the fall of the western Roman Empire. The cosmological dark ages. The time in our universe, billions of years ago, before the formation of the first stars. And we need to talk about the cosmic dawn: the birth of those first stars, a tumultuous epoch that completely reshaped the face the cosmos into its modern form.

Those first stars may have been completely unlike anything we see in the present universe. And we may, if we’re lucky, be on the cusp of seeing them for the first time.

Continue reading “We May Soon Be Able To See the First, Supergiant Stars in the Universe”

November 19, 2018 by Matt Williams

Astronomers Finally Spot the Type of Star That Leads to Type 1C Supernovae

Artist's impression of the blue supergiant that underwent a Type Ic supernova in 2017. Credits: NASA, ESA, and J. Olmsted (STScI)

As astronomical phenomena go, supernovae are among the most fascinating and spectacular. This process occurs when certain types of stars reach the end of their lifespan, where they explode and throw off their outer layers. Thanks to generations of study, astronomers have been able to classify most observed supernovae into one of two categories (Type I and Type II) and determine which kinds of stars are the progenitors for each.

However, to date, astronomers have been unable to determine which type of star eventually leads to a Type Ic supernova – a special of class where a star undergoes core collapse after being stripped of its hydrogen and helium. But thanks to the efforts of two teams of astronomers that pored over archival data from the Hubble Space Telescope, scientists have now found the long sought-after star that causes this type of supernova.

Continue reading “Astronomers Finally Spot the Type of Star That Leads to Type 1C Supernovae”

November 15, 2018November 19, 2018 by Paul M. Sutter

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”