New Neighbors!

Previously discovered dwarf satellite galaxies (in blue) and the newly discovered candidates (in red) (Yao-Yuan Mao, Ralf Kaehler, Risa Wechsler (KIPAC/SLAC))

We have some new galactic neighbors! Well, actually maybe “new” is not the right term: they have been there for a long time but we only just now noticed. Astronomers are reporting the discovery of nine dwarf satellite galaxies orbiting the Milky Way like remoras stuck to a cosmic shark. These nine miniature galaxies are additional to the well-known Large and Small Magellanic Clouds—two dwarf galaxies which are located right next to the Milky Way (being respectively 160,000 and 200,000 light years away).

The new dwarf galaxies were discovered by a team of astronomers poring over data recovered from the Dark Energy Survey (a super-high resolution digital array which is part of the Victor M Blanco telescope in the Andes). The closest is a mere 97,000 light years from the Milky Way whereas the farthest lies 1.2 million light years away from us. The dwarf galaxies are a billion times fainter than the Milky Way. They are made up of millions (or hundreds of millions or even billions) of stars but are insignificant in size compared to the hundreds of billions of stars which constitute a true galaxy. Scientists believe that there are hundreds of similar miniature galaxies and pseudo-galaxies near the Milky Way, but they are dark and difficult to find (comparitively speaking).

The Large and Small Magellanic Clouds, near which the satellites were found. (image from European Southern Observatory)

I have been saying “dwarf galaxies” because I like the way it sounds (like the new galaxies live together in the woods in a little hut and work in the mines!), but actually only three of the new companions are definitely dwarf galaxies. The remaining six structures may be dwarf galaxies or they may merely be globular clusters—a far less euphonic phrase which indicates a group of stars which orbits a galactic core as a satellite. Unlike globular clusters, dwarf galaxies are held together by the gravitational mass of large quantities of dark matter (um, assuming it actually exists). Indeed dwarf galaxies seem to contain far greater quantities of dark matter than actual galaxies. This makes the newly discovered galactic neighbors a potentially useful focus for studying the properties of dark matter and refining our model of the universe.

Messier 82 (Home of Cosmic Mysteries and Exploding Stars)

A mosaic image taken by the Hubble Telescope of Messier 82 (NASA, ca. 2000)

Twelve million light years from Earth lies Messier 82, a starburst galaxy 5 times more luminous than the entire Milky Way galaxy.  Messier 82 (AKA M82) is a very happening and dynamic galaxy: stars are being created there at an exceptionally high rate—most likely because the galaxy is “interacting” (or possibly colliding) with its neighboring galaxy M81. In 2005, the Hubble Space Telescope detected nearly 200 massive starburst clusters near M82’s center. Within these huge masses of dust and gas, stars are being birthed (and dying) at an astonishing rate.  The high energy released by this cosmic upheaval is nearly constant and the outflow of charged particles from M82 is evocatively known as “superwind”.

Lovell Telescope, Jodrell Bank Observatory (Mike Peel; Jodrell Bank Centre for Astrophysics, University of Manchester)

In 2010, astronomers working at Jodrell Bank Observatory in England discovered a mystery at the heart of M82: an unknown object was emitting high energy electromagnetic radiation in a pattern unlike anything else so far observed in the universe.  The mystery object appeared to be moving at 4 times the speed of light (which is, of course, quite impossible according to the standard model of the universe.  Newscientist.com offered the following explanation (of sorts) for the mystery object’s perceived velocity:

Such apparent “superluminal” motion has been seen before in high-speed jets of material squirted out by some black holes. The stuff in these jets is moving towards us at a slight angle and travelling at a fair fraction of the speed of light, and the effects of relativity produce a kind of optical illusion that makes the motion appear superluminal.

At present, the best explanation astronomers have for the mystery is that it is some sort of microquasar or black hole which is interacting in an unusual way with the tumultuous mass within a starburst cluster.  At present, the mystery is unexplained.

A super-dramatic before-and-after animation/photo of the type Ia supernova in M82

However, at present, M82 is doing entirely different things which have captured the attention of the international astronomy community.  On January 21^st, 2014, Steve Fossey and a group of his students at University College London spotted a colossal explosion within M82.  The event was quickly identified as a type Ia supernova, a bright and consistently energetic star explosion which occurs in binary stars where at least one star is a white dwarf (the dead, but energetic fragment of a larger star).   CBS News explains the phenomenon and its historical significance:

[When a] white dwarf siphons off too much mass from its companion star, a runaway nuclear reaction begins inside the dead star, leading to a brilliant supernova. Because Type Ia supernovas are believed to shine with equal brightness at their peaks, they are used as “standard candles” to measure distances the universe.

The supernova in M82 is the nearest supernova of its type observed since Supernova 1987A was spotted in February 1987 in the Large Magellanic Cloud (the dwarf galaxy which is companion to the Milky Way).  Telescopes around Earth are turning towards Ursa Major (where M82 is located in the sky).  Although the supernova is big news here, it is a very stale story in M82 where this all happened 12 million years ago.

An Artist’s Conception of a Type Ia Supernova

Honey Bees in Winter

Honey Bee (Apis mellifera)

Out of all the hymenoterans, Ferrebeekeeper has been looking forward to writing about honey bees.  Not only is honey delicious (and the striped workaholic insects strangely endearing), but honey bees have one of the most successful colony systems extant.  As noted in a previous post, a hive of honey bees is a conundrum—is it 50,000 souls working together in a city state or is it one living organism?  Unfortunately, as one reads through the writings by beekeepers, one realizes that it is not easy to answer this question—or even to write a short essay concerning honey bees.  Their societies are too complex to be readily summarized.  Writing about a hive of honey bees really is like writing about the myriad affairs of a city-state.  The bees forage in different locations, store their produce in different forms, build structures, establish castes, fights wars, and undergo succession crises.

All of that is true during the warm part of the year. As temperatures drop to around 20° Celsius (50° Fahrenheit), things change a great deal within the hive.  Honey bees do not hibernate like bears (or like bumblebees which also snuggle down in a little lined den) instead they use honey stores and teamwork to stay warm.  Honey bees do not have internal warming mechanisms like mammals, but they have each other and they have powerful wing muscles.  The bees cluster together into a ball with the queen at the middle.  Worker bees close to the queen shiver their wing muscles and thereby generate heat.  Workers at the outside of the ball act as insulation (and benefit from transferred heat).  If the ball becomes too hot it expands outward and the space between bees allows heat to escape.  If it becomes too cold the bees press inward.  Tired workers move towards the outside of the ball where they can be inert whereas cold workers on the outside move towards the inside.  You might notice I am only writing about female bees—the workers and the queen—this is because all of the male drone bees are regarded as expendable and are thrown out of the hive to die in the cold as soon as temperatures drop.

In the beginning of the cold season  the queen is not laying eggs (broodless) and the temperature within the cluster is about  27 °C (81 °F), however as spring nears a new brood of workers is needed and the interior temperature of the cluster rises to 34 °C (93 °F) in order to make egg-laying possible.  Hives with too few bees can not stay warm this way and they perish in cold winters, however adequately large hives with ample honey reserves can survive temperatures which dip deep deep below freezing. Even in large well-provisioned hives there are winter dangers though.  Moisture can build up in heavily insulated hives and form icicles which subsequently drip down on the bees in non-freezing weather and chill them (or burden them with fungi).  And prolonged deep cold can prove disastrous. The bees congregate around a single honey store when the temperatures are extremely cold and then they spread out and move to another honey deposit when the weather is better.  If the weather stays too cold for too long they deplete all of the honey and freeze—inches from abundant supplies of life-giving honey.