What's That Star Called?

The Pleiades

Actually, this time it’s a bunch of stars. You’ve probably noticed them before and you may know their name – the Pleiades or seven sisters. It’s a tight grouping of stars visible in the winter sky. We can currently see them rising in the east after sunset. They aren’t spectacularly bright, but striking enough to have made their mark in many cultures’ skylore.

The Pleiades are up by sunset, but won’t be easily spotted until after 7:00 or so at which time they’ll be more than the length of one fist held at the end of your arm above the horizon. On the nights of the 16th, 17th and 18th of November, the Moon passes the Pleiades, helping guide your eye towards them.

Check Skynews.ca for a detailed chart.

The November full Moon is found in Taurus, near 1st-magnitude star Aldebaran. Courtesy Skynews.ca

Look to see at least 5 or 6 stars. Under really darks skies and with good eyesight, you can see many more stars there. A simple pair of binoculars, even small ones, will help reveal that there are hundreds of stars associated with the Pleiades.

Why? Well, these stars are connected together by gravity. Literally “sisters,” the stars formed together out of the same cloud of gas and dust. In fact, in long exposure photographs, the dust is still visible, reflecting light from the nearby stars tinting the entire cluster blue.

We explored how stars die looking at nearby Aldebaran, almost directly underneath the Pleiades in the evening sky. The Seven Sisters show us the opposite end of stellar life. These are young stars. Stars form inside giant clouds of gas and dust called nebulae.

Over time nearby stellar activity can perturb the gas in the cloud. Gravity then causes it to collapse and pull itself into a round ball. The gas at the centre of the ball becomes very compressed and hot, so much so that eventually, the atoms in the gas are stripped of their electrons, leaving only the atomic nuclei behind.

Having a positive charge, the nuclei naturally repel each other. But get them moving fast enough and they can overcome this repulsion and slam into one another forming heavier nuclei and releasing energy that we see as light. These nuclear reactions are what power a star, giving it the energy to fight against the gravitational collapse.

As all of this is going on, you can imagine that it creates even more disturbances in the nebula, triggering more collapsing gas and forming more stars. In other words, stars tend to form in groups, families if you like.

Long before this was determined by telescoping observation, people around the world admired this star cluster. The Seven Sisters were the seven daughters of Atlas the Titan who held up the sky and Pleione, a sea-nymph. As Atlas was otherwise occupied, many suitors pursued the sisters, including Orion the Hunter.

The Inuit tell a story of pack of dogs chasing a bear. There are many stories from North American Indigenous groups about the stars being a group of playmates that wandered either wandered off, did not do their chores or were abandoned by the tribe. In China, the cluster represents the hairy head of the White Tiger of the West, one of the cardinal “four symbols” of the Chinese sky.

 But perhaps most well-known, at least to car drivers, is the Japanese name for this stellar group -- Subaru, meaning “gathering together.” This name was chosen to mark the 5 companies that merged to form it.

Astronomy Picture of the Day gorgeous photo of the Pleiades, also known as M45:

For a comprehensive site about the Pleiades, check out this page from the Arecibo Telescope’s website.

To see the Pleiades in many different wavelengths of light, go to Cool Cosmos

Mississauga Councillor Ron Starr Supports Planetarium Project

October 23, 2013

Mr. Randy Attwood,

President, The Earthshine Astronomy & Space Science Organization 

Dear Randy,

It is always satisfying to hear stories of the many educational endeavors organizations such as Earthshine undertake in the city especially where the youth is concerned. Any organization that promotes an environment fostering growth and development in our community is one I will readily support.

I share Earthshine's vision of commitment to developing a well-rounded, wholesome educational curriculum for elementary school students within the classroom, further enhanced by organizations like Earthshine outside the classroom. With its unique focus on promoting science and technology education through the astronomical sciences, Earthshine will be the first of its kind and a welcome addition to Mississauga.

I encourage people in our community to get involved with and support this project, as it is a great addition to our community and allows for the spread of innovative and beneficial science education.

I commend your efforts towards this goal and wish you the best of luck. I look forward to attending your "Exploring the Universe" presentation in the near future.

Sincerely, 

Ron Starr

Councillor Ward 6

What's That Star Called?

Aldebaran

When Aldebaran rises not too long after sunset, you know winter is on the way. It’s now well visible in the east by 8:30 pm. Capella lies to the north.

Aldebaran is the eye of Taurus the Bull, a prominent winter constellation. The rest of the Bull’s face is a ‘v’ shape with Aldebaran at one tip and running to the south and back up again to another much dimmer star called Ain. Aldebaran forms the Bull’s fiery eye.

In dark skies, or when the moon is close by, Aldebaran takes on a reddish-orange tint. This is another red giant star, like Betelgeuse, only not quite as big, but like Betelgeuse, nearing the end of its shining life.

Stars are in a constant tug of war between gravity, which pulls the star inwards, and energy generated in the star’s core, which pushes back outwards. The fuel powering Aldebaran is running low. When it drains completely, the star will no longer be able push back out and gravity will win. The star’s core will collapse into an extremely dense object, essentially a ball of neutrons called a neutron star. One teaspoon of neutron star material would weight several million tons at Earth’s surface.

This extremely dense core forms a solid wall into which the rest of the star’s layers will slam as they rush inwards during the implosion. This inflow of gas will ricochet off this dense core creating a massive explosion and dazzling amounts of light energy – a supernova.

The neat thing about supernovas, apart from the fact that they are among the most energetic events that can happen in our universe, is that they are responsible for more than half of the elements on our periodic table.

Our universe started with hydrogen and a tiny bit of helium. Then nuclear reactions in stars changed things. Nuclear reactions are what gives stars the energy to fight the tug of gravity. Stars are most often turning hydrogen into helium by slamming hydrogen nuclei together. When the star runs low on hydrogen, it slams helium together to form oxygen, carbon and a few other heavier elements. Once most stars try this, they actually make too much energy and not only balance the inward tug of gravity, but actually blow the star’s outer layers, with the newly-minted helium and heavier elements, gently into space.

In the largest stars, however, things work a bit longer, until the star begins to try and fuse iron atoms together. To do this, the reaction actually requires energy to work – and robs it from its surroundings, causing the star to quickly use up the energy in its core causing it to collapse into a neutron star.

But the neat thing happens as the outer gases ricochet off the core of the star. These atoms pick up neutrons from the core, in an extra fast nuclear reaction.

Slamming neutrons into the nucleus of an atom completely changes its characteristics – the number of protons and neutrons in an atom’s core is what determines that atom’s position on the periodic table – whether it is reactive, conducting, radioactive, shiny, etc. So the gases emerging from a supernova are enriched with all sorts of interesting atoms. In fact, it seems that everything in our universe with an atomic number higher than 26, iron’s spot on the periodic table, is either made in a dying star, or in a laboratory. It makes you think next time you admire a shiny piece of gold jewelry or a silver spoon...

Supernova 1987A, discovered by Ian Shelton (working for the University of Toronto at the time):

Link to youtube computer simulation of supernova

As supernovas are very hot, their remnants are often still glowing in super-energetic x-rays. The Chandra X-Ray Observatory has a fantastic gallery of supernova remnants

See how well they match the computer simulated predictions!

Famous supernovas:

Tycho’s Supernova, observed by Tycho Brahe in 1572. Located in Cassiopeia

Crab Nebula: located in Taurus the Bull, off the other side of his face, was created in a widely observed supernova in 1054  AD. It’s still expanding outwards, as seen in this video:

New image of Saturn and inner planets released

A spectacular image of Saturn showing the Earth, Venus and Mars was released today by NASA. The image was taken last July by the Cassini spacecraft, in orbit around Saturn. It was taken when the Sun was in eclipse.  The various moons of Saturn as well as the inner planets are labelled in this image. 

NASA Press Release follows: 

NASA has released a natural color image of Saturn from space, the first in which Saturn, its moons and rings, and Earth, Venus and Mars, all are visible.

The new panoramic mosaic of the majestic Saturn system taken by NASA's Cassini spacecraft, which shows the view as it would be seen by human eyes, was unveiled at the Newseum in Washington on Tuesday.

Cassini's imaging team processed 141 wide-angle images to create the panorama. The image sweeps 404,880 miles (651,591 kilometers) across Saturn and its inner ring system, including all of Saturn's rings out to the E ring, which is Saturn's second outermost ring. For perspective, the distance between Earth and our moon would fit comfortably inside the span of the E ring. 

"In this one magnificent view, Cassini has delivered to us a universe of marvels: from spokes in Saturn's main rings to the spray erupting from the icy moon Enceladus, from the shadows of moons cast through the gorgeous blue E ring to the inner planets Venus, Mars, and our own planet Earth, far in the distance," said Carolyn Porco, Cassini's imaging team lead based at the Space Science Institute in Boulder, Colo. "And it did so on a day people all over the world, in unison, smiled in celebration at the sheer joy of being alive on a pale blue dot."

The mosaic is part of Cassini's "Wave at Saturn" campaign, where on July 19, people for the first time had advance notice a spacecraft was taking their picture from planetary distances. NASA invited the public to celebrate by finding Saturn in their part of the sky, waving at the ringed planet and sharing pictures over the Internet. 

An annotated version of the Saturn system mosaic labels points of interest. Earth is a bright blue dot to the lower right of Saturn. Venus is a bright dot to Saturn's upper left. Mars also appears, as a faint red dot, above and to the left of Venus. Seven Saturnian moons are visible, including Enceladus on the left side of the image. Zooming into the image reveals the moon and the icy plume emanating from its south pole, supplying fine, powder-sized icy particles that make up the E ring. 

The E ring shines like a halo around Saturn and the inner rings. Because it is so tenuous, it is best seen with light shining from behind it, when the tiny particles are outlined with light because of the phenomenon of diffraction. Scientists who focus on Saturn's rings look for patterns in optical bonanzas like these. They use computers to increase dramatically the contrast of the images and change the color balance, for example, to see evidence for material tracing out the full orbits of the tiny moons Anthe and Methone for the first time. 

"This mosaic provides a remarkable amount of high-quality data on Saturn's diffuse rings, revealing all sorts of intriguing structures we are currently trying to understand," said Matt Hedman, a Cassini participating scientist at the University of Idaho in Moscow. "The E ring in particular shows patterns that likely reflect disturbances from such diverse sources as sunlight and Enceladus' gravity."

Cassini does not attempt many images of Earth because the sun is so close to our planet that an unobstructed view would damage the spacecraft's sensitive detectors. Cassini team members looked for an opportunity when the sun would slip behind Saturn from Cassini's point of view. A good opportunity came on July 19, when Cassini was able to capture a picture of Earth and its moon, and this multi-image, backlit panorama of the Saturn system.

"With a long, intricate dance around the Saturn system, Cassini aims to study the Saturn system from as many angles as possible," said Linda Spilker, Cassini project scientist based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Beyond showing us the beauty of the Ringed Planet, data like these also improve our understanding of the history of the faint rings around Saturn and the way disks around planets form -- clues to how our own solar system formed around the sun."

Launched in 1997, Cassini has explored the Saturn system for more than nine years. NASA plans to continue the mission through 2017, with the anticipation of many more images of Saturn, its rings and moons, as well as other scientific data.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France, and Germany. The imaging operations center and team leader (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

What Star is That?

Capella

The bright star Capella shines in the East tonight. By 7:30, it will be 15 degrees up – the end of a fist held out lengthways at the end of your arm marks about how high Capella will be 2 hours after sunset.

Capella is the 3rd brightest star in the northern sky and the 6th brightest star of all (not counting the Sun!) When she’s low in the sky, Capella can exhibit a remarkable effect, flashing many different colours, from white to blue the red. This happens as the star’s light travels through Earth’s atmosphere. Any star can twinkle as the air its light travels through shifts and changes. But a star low on the horizon can also appear to change colour just as the Sun does when it sets.

You can find a lot of videos of stars doing this on the internet labelled, “Flashing star?” or “UFO?”... it’s a star. The effect is common but it is very striking when the atmospheric conditions are right. (see video below)

Capella is the brightest star in the constellation Auriga the Charioteer. This constellation looks like a giant pentagon or upside down cupcake, the rest of which will become more easily visible after 9 pm tonight.

Capella in the constellation Auriga. Credit: Wikipedia CC.

Capella’s name means she-goat. Look carefully and you’ll see her kids, three stars forming a tiny triangle directly east of the star. It is one of the few stars that keeps a Latinized name – most are called by their Arabic translations. But a star this bright has had many names throughout history. In India, the star was seen as the heart of Brahma, Brahma Hidaya and in ancient Peru, Capella was seen as a shepherd star called Colca. The ancient Mayans aligned windows towards Capella and other bright stars.

Auriga the Charioteer or Shepherd    Credit: Hubblesource

Study suggests 40 billion Earth-sized planets in Milky Way

NASA announced today that Kepler space telescope data shows that there are 40 billion Earth-sized (not necessarily Earth-like) planets in the Milky Way Galaxy. 

Earthshine President Randy Attwood discussed this announcement on CTV's Canada AM this morning. 

For more information here is an article in the New York Times. Also, check out this New York TImes graphic.

And this video.