White dwarf supernovas—more officially known as type Ia supernovas—are important to cosmologists because they all explode in very similar ways. That means they can be used to measure distances to faraway galaxies. However, a peculiar type of supernova, first identified in 2002, has a lot in common with type Ia explosions, but with a lot less energy. Some astronomers are now saying this could be a new class of white dwarf supernova that produces much less light and sends material into interstellar space at far lower speeds.

Beginning in 2002, astronomers started recognizing a peculiar type of explosion. Since then, they’ve identified 25 of them; they resemble white dwarf supernovas in many respects, but strongly differ in others. A new paper by Ryan J. Foley and colleagues offered an explanation: these were an entirely new type of white dwarf explosion, one involving less energy and more material from a companion star. So much less energy, in fact, that the authors suspect that the white dwarf may not be fully destroyed in these odd events. [Read more…]

Baby boom-ers could be a new type of white dwarf supernova

Eta Carinae, one of the best candidates for going supernova in our lifetimes - assuming we understand the physics of the system, which we don't. [Credit:  NASA, ESA, and the Hubble SM4 ERO Team]Supernovas are some of the most violent phenomena in the cosmos, but we’re in no immediate danger from one. However, astronomers would really really really like one to go off relatively nearby during our lifetimes, since we would learn a lot from observing one. My latest piece at Ars Technica is a gallery showing some of the more interesting supernova candidates in our galaxy, including a few that might possibly go kaboom while I’m still around to see it happen.

Supernovas and Marvin the Martian

Ryan Gosling has not endorsed this class, but if he knew about it, he would.

Ryan Gosling has not endorsed this class, but if he knew about it, he would.

OK, one part of that title isn’t true, unless Ryan Gosling signs up for the class in the next few days. There are still spots in my new online class “The Universe in a Box”, beginning next Tuesday, April 2. Sign up today!

Also, we’re beginning another new class at CosmoAcademy: “The Sun and Stellar Evolution“, taught by Ray Sanders. He’ll teach you about the life cycle of stars, from formation to death and beyond, and what our own Sun can tell us about the whole process. The class begins April 15.

Learn cosmology with me and Ryan Gosling

My second piece for BBC Future is up! I ask—and partly answer—the question, “Will we ever detect gravitational waves directly?” (And don’t worry if you don’t know what a gravitational wave is: I answer that one too!)

A major part of the problem is that gravity is weak: even the strongest gravitational wave will only nudge an atom by a tiny amount. Additionally, the wavelength of gravitational radiation – the distance over which a wave repeats itself – is often similar to the size of the objects emitting it. So, while radio waves from pulsars may have wavelengths measured in centimetres, the gravitational radiation emitted could have wavelengths measured in kilometres. Which means that you most likely need detectors of a similar size to detect them. [Read more…]

For those of you in the UK, you might need to use this link instead, due to weird issues with the BBC website.

Gravitational waves: the froth of spacetime

The cosmic pie, via Planck. [Credit: ESA/Planck Collaboration]

The cosmic pie, via Planck. [Credit: ESA/Planck Collaboration]

For cosmology-lovers like me, yesterday was a full, busy day. The Planck telescope released its first full set of data, refining the estimates of the age of the Universe and its contents. I wrote two big pieces, one for Ars Technica and one for Galileo’s Pendulum.

  • First Planck results: the Universe is still weird and interesting [Ars Technica]. “By comparing theoretical models to the real CMB, cosmologists determined that dark energy—the mysterious substance driving cosmic acceleration—comprises 68.3 percent of the energy content of the Universe, down slightly from earlier estimates of 72.8 percent. Similarly, dark matter’s contribution was boosted from 22.7 percent to 26.8 percent, while ordinary matter’s share went from 4.5 percent to 4.9 percent.”
  • Planck results: our weird and wonderful Universe [Galileo’s Pendulum].  “The big news today is that our Universe is a little older than we thought, has a little more matter in it, and is every bit as strange as we’ve come to expect. Some numbers got shifted around a bit, but things are pretty much what we cosmology-watchers expected. It’s not a bad thing, in my opinion. After all, we still don’t know what dark matter is, we still don’t know what dark energy is, and we still don’t understand inflation completely. Adding weirdness to weirdness is probably more than our poor brains could take right now.”

Charlie Petit at the Knight Journalism Tracker also has a great round-up of articles on Planck, for those who want a more mainstream approach than my “techy” one (to use Petit’s term).

Planck: news from the infant Universe

Imagine a planet 7 times the mass of Jupiter, hot enough to glow slightly, and containing dusty clouds of carbon monoxide and water. That planet is HR 8799c, one of the few worlds outside our Solar System which astronomers have been able to image directly. Part of the reason for its weirdness is its youth: the planet is only about 30 million years old, compared to the Solar System’s 4.5 billion-year age. In fact, up until an observation published this week, astronomers couldn’t be sure HR 8799c was even a planet: many of its properties make it look more like a brown dwarf, the star-like objects not quite massive enough to shine via nuclear fusion. Despite its strange aspects, the planet could help astronomers understand how the HR 8799 system formed—and reveal information about the origins of our own Solar System.

Quinn Konopacky, Travis Barman, Bruce Macintosh, and Christian Marois performed a detailed spectral analysis of the atmosphere of the possible exoplanet. They compared their findings to the known properties of a brown dwarf and concluded that they don’t match—it is indeed a young planet. Chemical differences between HR 8799c and its host star led the researchers to conclude the system likely formed in the same way the Solar System did. [Read more…]

Analysis of atmosphere reveals: weird exoplanet is weird

Prototypes of the kind of telescope used in ALMA, at the Jansky Very Large Array in New Mexico. When I took this photo, the prototypes were being actively dismantled for shipment to other sites.

Prototypes of the kind of telescope used in ALMA, at the Jansky Very Large Array in New Mexico. When I took this photo, the prototypes were being actively dismantled for shipment to other sites.

I’m a theoretical physicist by training and inclination, but I’m not immune to awesome experiments or observatories. (Ahem.) Case in point: the new Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. This array of 66 telescopes in the high Atacama Desert is particularly well suited to hunt for the earliest galaxies and stars in the Universe. Their early scientific results—timed for the official inauguration of the array this week—bear that out, with the measurement of the distances to several star-forming galaxies that formed less than 1.5 billion years after the Big Bang. What makes it even better? My article appeared today, which is Albert Einstein’s birthday, and ALMA scientists used gravitational lensing—an effect predicted from Einstein’s general theory of relativity—to locate these galaxies.

The galaxies of the Universe’s youth worked busily at making stars—that much is certain. However, what did those galaxies look like? How many were there, and how were they distributed in space and time?

Over such huge distances, those galaxies appear faint to us, so it’s only within the last decade or so that astronomers have been able to start obtaining a reasonable view of them. The newly inaugurated ALMA (Atacama Large Millimeter/submillimeter Array) is one of the most promising telescope arrays in the world for making observations of the early Universe. [Read more…]

In which I get a little fanboyish about ALMA