July 1, 2016

Banff National Park

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Banff National Park is Canada's oldest national park, established in 1885 in the Rocky Mountains. The park, located 110–180 kilometres (68–112 mi) west of Calgary in the province of Alberta, encompasses 6,641 square kilometres (2,564 sq mi) of mountainous terrain, with numerous glaciers and ice fields, dense coniferous forest, and alpine landscapes. The Icefields Parkway extends from Lake Louise, connecting to Jasper National Park in the north. Provincial forests and Yoho National Park are neighbours to the west, while Kootenay National Park is located to the south and Kananaskis Country to the southeast. The main commercial centre of the park is the town of Banff, in the Bow River valley.

The Canadian Pacific Railway was instrumental in Banff's early years, building the Banff Springs Hotel and Lake Louise Chalet, and attracting tourists through extensive advertising. In the early 20th century, roads were built in Banff, at times by war internees from World War I, and through Great Depression-era public works projects. Since the 1960s, park accommodations have been open all year, with annual tourism visits to Banff increasing to over 5 million in the 1990s. Millions more pass through the park on the Trans-Canada Highway. As Banff has over three million visitors annually, the health of its ecosystem has been threatened. In the mid-1990s, Parks Canada responded by initiating a two-year study, which resulted in management recommendations, and new policies that aim to preserve ecological integrity.

Banff National Park has a subarctic climate with three ecoregions, including montane, subalpine, and alpine. The forests are dominated by Lodgepole pine at lower elevations and Engelmann spruce in higher ones below the treeline, above which is primarily rocks and ice. Mammal species such as the grizzly, cougar, wolverine, elk, bighorn sheep and moose are found, along with hundreds of bird species. Reptiles and amphibians are also found but only a limited number of species have been recorded. The mountains are formed from sedimentary rocks which were pushed east and over newer rock strata between 80 and 55 million years ago. Over the past few million years, glaciers have at times covered most of the park, but today are found only on the mountain slopes though they include the Columbia Icefield, the largest uninterrupted glacial mass in the Rockies. Erosion from water and ice have carved the mountains into their current shapes.

Explanation from: https://en.wikipedia.org/wiki/Banff_National_Park

IC 2118: The Witch Head Nebula

IC 2118: The Witch Head Nebula

IC 2118 (also known as Witch Head Nebula due to its shape), is an extremely faint reflection nebula believed to be an ancient supernova remnant or gas cloud illuminated by nearby supergiant star Rigel in Orion. It lies in the Eridanus constellation, about 900 light-years from Earth. The nature of the dust particles, reflecting blue light better than red, is a factor in giving the Witch Head its blue color. Radio observations show substantial carbon monoxide emission throughout parts of IC 2118 an indicator of the presence of molecular clouds and star formation in the nebula. In fact candidates for pre-main sequence stars and some classic T-Tauri stars have been found deep within the nebula.

The molecular clouds of IC 2118 are probably juxtaposed to the outer boundaries of the vast Orion-Eridanus bubble, a giant supershell of molecular hydrogen blown by the high mass stars of the Orion OB1 association. As the supershell expands into the interstellar medium, favorable circumstances for star formation occur. IC 2118 is located in one such area. The wind blown appearance and cometary shape of the bright reflection nebula is highly suggestive of a strong association with the high mass luminous stars of Orion OB1. The fact that the heads of the cometary clouds of IC2118 point northeast towards the association is strong support of that relationship.

Image Credit & Copyright: Jeff Signorelli
Explanation from: https://en.wikipedia.org/wiki/IC_2118

Messier 51

Messier 51 (M51) or NGC 5194

Nearly a million seconds of observing time with NASA’s Chandra X-ray Observatory has revealed a spiral galaxy similar to the Milky Way glittering with hundreds of X-ray points of light.

The galaxy is officially named Messier 51 (M51) or NGC 5194, but often goes by its nickname of the “Whirlpool Galaxy.” Like the Milky Way, the Whirlpool is a spiral galaxy with spectacular arms of stars and dust. M51 is located 30 million light years from Earth, and its face-on orientation to Earth gives us a perspective that we can never get of our own spiral galactic home.

By using Chandra, astronomers can peer into the Whirlpool to uncover things that can only be detected in X-rays. In this new composite image, Chandra data are shown in purple. Optical data from the Hubble Space Telescope are red, green and blue.

Most of the X-ray sources are X-ray binaries (XRBs). These systems consist of pairs of objects where a compact star, either a neutron star or, more rarely, a black hole, is capturing material from an orbiting companion star. The infalling material is accelerated by the intense gravitational field of the compact star and heated to millions of degrees, producing a luminous X-ray source. The Chandra observations reveal that at least ten of the XRBs in M51 are bright enough to contain black holes. In eight of these systems the black holes are likely capturing material from companion stars that are much more massive than the sun.

Because astronomers have been observing M51 for about a decade with Chandra, they have critical information about how X-ray sources containing black holes behave over time. The black holes with massive stellar companions are consistently bright over the ten years of Chandra observations. These results suggest that the high-mass stars in these X-ray sources also have strong winds that allow for a steady stream of material to flow onto the black hole.

A difference between the Milky Way and the Whirlpool galaxy is that M51 is in the midst of merging with a smaller companion galaxy seen in the upper left of the image. Scientists think this galactic interaction is triggering waves of star formation. The most massive of the newly formed stars will race through their evolution in a few million years and collapse to form neutron stars or black holes. Most of the XRBs containing black holes in M51 are located close to regions where stars are forming, showing their connection to the oncoming galactic collision.

Previous studies of the Whirlpool Galaxy with Chandra revealed just over 100 X-ray sources. The new dataset, equivalent to about 900,000 seconds of Chandra observing time, reveals nearly 500 X-ray sources. About 400 of these sources are thought to be within M51, with the remaining either being in front of or behind the galaxy itself.

Much of the diffuse, or fuzzy, X-ray emission in M51 comes from gas that has been superheated by supernova explosions of massive stars.

Image Credit: X-ray: NASA/CXC/Wesleyan Univ./R.Kilgard, et al; Optical: NASA/STScI
Explanation from: http://www.nasa.gov/mission_pages/chandra/multimedia/sparkling-m51.html