ECLIPSE NEWSLETTER The Eclipse Newsletter is dedicated to increasing the knowledge of Astronomy, Astrophysics, Cosmology and related subjects. VOLUME 3 - NUMBER 4 JULY – AUGUST 2019 PLEASE SEND ALL PHOTOS, QUESTIONS AND REQUST FOR ARTICLES TO [email protected] ALL PREVIOUS ISSUES OF ECLIPSE CAN BE FOUND AT mountcuba.org SPECIAL NOTE. LOTS OF NEW AND EXCITING THINGS HAPPENING AT MOUNT CUBA ASTRONOMICAL OBSERVATORY. PLEASE VISIT THEIR SITE. YOU MAY EVEN FIND A MEMBERSHIP WOULD BE A GOOD IDEA. 1 CONTENTS: SOMBRERO GALAXY – M104 DO GALAXIES COLLIDE AND WHAT HAPPENS IF THEY DO? Milky Way Versus Andromeda As Seen from Earth WHAT IS THE LIFECYCLE OF A STAR? PART 4. ARE WE MADE OF STAR DUST? SOME FAMIOUS PHOTOS FROM HUBBLE. GET RICH QUICK? PSYCHE 16. METEOR SHOWERS FOR JULY AND AUGUST. THOSE INTERESTING METEOR. SATURN’S MOON ENCELADUS COULD SUPPORT LIFE. If you see text in green, my hope is you will do some research. I will continue to use hyperlinks. Just swipe, right click, open hyperlink. Hyperlinks are in Blue. 2 THE SOMBERO GALAXY – M104 Why does the Sombrero Galaxy look like a hat? Reasons include the Sombrero's unusually large and extended central bulge of stars, and dark prominent dust lanes that appear in a disk that we see nearly edge-on. Billions of old stars cause the diffuse glow of the extended central bulge. Close inspection of the bulge in the above photograph shows many points of light that are actually globular clusters. The spectacular dust rings harbor many younger and brighter stars, and show intricate details astronomers don't yet fully understand. The very center of the Sombrero is thought to house a large black hole. Fifty million-year-old light from the Sombrero Galaxy can be seen with a small telescope towards the constellation of Virgo. 3 Sombrero Galaxy Profile Constellation: Virgo Also known as: Messier Object 104, M104 or NGC 4594 Type: Spiral Galaxy Diameter: 50,000 light years Distance: 29 light years Mass: 800 billion M☉ Number of Stars: 100+ billion Interesting facts. One of the minor characters from the Superman comics is “Vartox.” He describes himself as coming from the planet Valeron in the “Sombrero Hat” Galaxy. The 1960’s television show “The Outer Limits” included a picture of the Sombrero Galaxy at the end of each show in its credits. Both the Milky Way and Sombrero Galaxies have globular clusters that are believed to be between 10 and 13 billion years old. The Sombrero Galaxy has up to 2,000 globular clusters at its core, which is around 10 times that of the Milky Way Galaxy. Using both the Hubble Space Telescope and the Spitzer Space Telescope, NASA has been studying the Sombrero Galaxy in both visible and infrared light. Until 1912, astronomers thought that the Sombrero Galaxy was a spiral nebula inside the Milky Way. Vesto Slipher, an American astronomer worked at the Lowell Observatory and proved that the Sombrero was a galaxy outside of the Milky Way. Slipher’s studies also proved that the Sombrero Galaxy was moving away from the Milky Way Galaxy and this was the first recognition of the expansion of the universe. 4 There are over 7 billion people on Earth. Researchers have estimated that the Sombrero Galaxy contains a minimum of 100 stars for each person on Earth. The “broad rim” of the hat shape is where the Sombrero has its dust lane that is made up of dust and hydrogen gas. The Sombrero dust lane contains almost all of the galaxy’s molecular cold gas and is thought to be the main site where its stars are created. Unlike some galaxies, researchers think that there aren’t many stars that form inside the Sombrero Galaxy’s nucleus. The Sombrero Galaxy is different in that it has characteristics of both elliptical and spiral galaxies in its appearance. Scientists speculated that the appearance of the Sombrero Galaxy looked like a spiral galaxy was swallowed by an elliptical galaxy. This would be impossible as it would destroy the spiral galaxy. Scientists now speculate that the shape of the Sombrero Galaxy is a large elliptical galaxy is due to 9 million years ago when a large elliptical galaxy accumulated a lot of gas clouds that flattened out to form the shape of a spiral galaxy. DO GALAXIES COLLIDE AND WHAT HAPPENS IF THEY DO? This illustration shows the merging of the Milky Way and the Andromeda Galaxies. 5 We don't want to scare you, but our own Milky Way is on a collision course with Andromeda, the closest spiral galaxy to our own. At some point during the next few billion years, our galaxy and Andromeda – which also happen to be the two largest galaxies in the Local Group – are going to come together, and with catastrophic consequences. Stars will be thrown out of the galaxy; others will be destroyed as they crash into the merging supermassive black holes. And the delicate spiral structure of both galaxies will be destroyed as they become a single, giant, elliptical galaxy. But as cataclysmic as this sounds, this sort of process is actually a natural part of galactic evolution. Astronomers have known about this impending collision for some time. This is based on the direction and speed of our galaxy and Andromeda's. But more importantly, when astronomers look out into the universe, they see galaxy collisions happening on a regular basis. Gravitational Collisions: Galaxies are held together by mutual gravity and orbit around a common center. Interactions between galaxies is quite common, especially between giant and satellite galaxies. This is often the result of a galaxies drifting too close to one another, to the point where the gravity of the satellite galaxy will attract one of the giant galaxy's primary spiral arms. In other cases, the path of the satellite galaxy may cause it to intersect with the giant galaxy. Collisions may lead to mergers, assuming that neither galaxy has enough momentum to keep going after the collision has taken place. If one of the colliding galaxies is much larger than the other, it will remain largely intact and retain its shape, while the smaller galaxy will be stripped apart and become part of the larger galaxy. Such collisions are relatively common, and Andromeda is believed to have collided with at least one other galaxy in the past. Several dwarf galaxies (such as the Sagittarius Dwarf Spheroidal Galaxy) are currently colliding with the Milky Way and merging with it. However, the word collision is a bit of a misnomer, since the extremely tenuous distribution of matter in galaxies means that actual collisions between stars or planets is extremely unlikely. Andromeda–Milky Way Collision: In 1929, Edwin Hubble revealed observational evidence which showed that distant galaxies were moving away from the Milky Way. This led him to create Hubble's Law, which states that a galaxy's distance and velocity can be determined by measuring its redshift – i.e. a phenomena where an object's light is shifted toward the red end of the spectrum when it is moving away. 6 However, spectrographic measurements performed on the light coming from Andromeda showed that its light was shifted towards the blue end of the spectrum (aka. blueshift). This indicated that unlike most galaxies that have been observed since the early 20th century, Andromeda is moving towards us. In 2012, researchers determined that a collision between the Milky Way and the Andromeda Galaxy was sure to happen, based on Hubble data that tracked the motions of Andromeda from 2002 to 2010. Based on measurements of its blueshift, it is estimated that Andromeda is approaching our galaxy at a rate of about 110 km/second (68 mi/s). At this rate, it will likely collide with the Milky Way in around 4 billion years. These studies also suggest that M33, the Triangulum Galaxy – the third largest and brightest galaxy of the Local Group – will participate in this event as well. In all likelihood, it will end up in orbit around the Milky Way and Andromeda, then collide with the merger remnant at a later date. Consequences: In a galaxy collision, large galaxies absorb smaller galaxies entirely, tearing them apart and incorporating their stars. But when the galaxies are similar in size – like the Milky Way and Andromeda – the close encounter destroys the spiral structure entirely. The two groups of stars eventually become a giant elliptical galaxy with no discernible spiral structure. Such interactions can also trigger a small amount of star formation. When the galaxies collide, it causes vast clouds of hydrogen to collect and become compressed, which can trigger a series of gravitational collapses. A galaxy collision also causes a galaxy to age prematurely, since much of its gas is converted into stars. After this period of rampant star formation, galaxies run out of fuel. The youngest hottest stars detonate as supernovae, and all that's left are the older, cooler red stars with much longer lives. This is why giant elliptical galaxies, the results of galaxy collisions, have so many old red stars and very little active star formation. Despite the Andromeda Galaxy containing about 1 trillion stars and the Milky Way containing about 300 billion, the chance of even two stars colliding is negligible because of the huge distances between them. However, both galaxies contain central supermassive black holes, which will converge near the center of the newly-formed galaxy. This black hole merger will cause orbital energy to be transferred to stars, which will be moved to higher orbits over the course of millions of years. When the two black holes come within a light year of one another, they will emit gravitational waves that will radiate further orbital energy, until they merge completely.