1. Supernovae Remnants Nest in Concentric Rings

Astronomers at the Instituto de Astrofisica de Canarias (IAC) have, for the first time, discovered the remnants of three supernovae expanding concentrically, one inside the other, like a set of cosmic Russian matryoshka dolls.  The so-called “superbubbles” of interstellar gas were noticed while observing galaxy M33 (Triangulum galaxy), which lies in the Local Group of galaxies less than three million light years away.

Artist’s rendition shows concentric rings emanating from three separate supernovae. [Credit: Gabriel Pérez/SMM (IAC)]

The first of the stars that left these amazing remnants is thought to have exploded about 114,000 years ago, and the others followed 40,000 and 21,000 years in the past.  The gaseous rings the supernovae produced range in size from 140 to only 41 light years across.  The stars that produced them must have been relatively close together, and they were probably about the same mass and age.

The results of the research were published in Monthly Notices Letters of the Royal Astronomical Society.

2. Astronomers Find a Dark Cousin of the Milky Way

Three hundred million light years away, in the Coma constellation, is a mysterious galaxy that may hold keys to understanding the nature of dark matter.  The dim galaxy is comparable in size to the Milky Way – about 100,000 light years wide, with approximately the same mass – but it has 100 times fewer stars.

Dragonfly 44 is estimated to be composed of 99.9% dark matter. (Image credit: Pieter van Dokkum/Roberto Abraham/Gemini Observatory/SDSS/AURA)

With so little collective gravity to hold them together, the stars should just drift apart.  Astronomers deduce that the only plausible explanation for the galaxy’s structural stability is the invisible presence of an enormous amount of dark matter, perhaps as much of the stuff as in its far more luminous cousin, our Milky Way.

Observed using an ingenious new telescope array called Dragonfly, which is owned by the University of Toronto, the galaxy has been named Dragonfly 44.  The array uses ten Canon 400mm lenses operating in synch.  The designers of the array, Pieter van Dokkum and Roberto Abraham, are among the authors of a recently published study focusing on the galaxy in The Astrophysical Journal Letters.

Pieter van Dokkum photographs dragonflies as a hobby.

3. Most Distant Galaxy Cluster Discovered

Using the Chandra X-Ray Observatory and other Earth- and space-based telescopes, astronomers have spied the most distant galaxy cluster thus far identified.  It has been given the rather cumbersome alphanumeric identifier CL J1011+0220 by researchers who will, no doubt, want to observe it repeatedly to mine a wealth of data from the object.

Galaxy cluster CL J1011+0220 is the most distant such grouping of galaxies identified so far. (Image credit: X-ray: NASA/CXC/CEA/T. Wang et al; Infrared: ESO/UltraVISTA; Radio: ESO/NAOJ/NRAO/ALMA)

“It appears that we have captured this galaxy cluster at a critical stage just as it has shifted from a loose collection of galaxies into a young, but fully formed galaxy cluster.” – David Elbaz, Atomic Energy Commission of France

The newfound galaxy cluster is about 11.1 billion light years distant, which means it is about 700 million years older than the previously most distant cluster that has been identified.  Apart from its age, what has excited astronomers is that it is generating new stars at an incredible rate.  It appears that the equivalent of 3,000 Suns are igniting in the core of the cluster per year.  This rate of star generation is much higher than what astronomers are accustomed to seeing in more recently organized galaxy clusters.