Pictures of The Day #2
2009.06.09: Markarian’s Chain of Galaxies
Across the heart of the Virgo Cluster of Galaxies lies a striking string of galaxies known as Markarian’s Chain. The chain, pictured above, is highlighted on the upper right with two large but featureless lenticular galaxies, M84 and M86. Prominent to their lower left is a pair of interacting galaxies known as The Eyes. The home Virgo Cluster is the nearest cluster of galaxies, contains over 2000 galaxies, and has a noticeable gravitational pull on the galaxies of the Local Group of Galaxies surrounding our Milky Way Galaxy. The center of the Virgo Cluster is located about 70 million light years away toward the constellation of Virgo. At least seven galaxies in the chain appear to move coherently, although others appear to be superposed by chance.
2009.06.10: A Dusty Iris Nebula
These clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the Iris Nebula and dutifully cataloged as NGC 7023, this is not the only nebula in the sky to evoke the imagery of flowers. Surrounding it, obscuring clouds of dust and cold molecular gas are also present and can suggest other convoluted and fantastic shapes. Within the Iris, dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight. Central filaments of the cosmic dust glow with a faint reddish photoluminesence as some dust grains effectively convert the star’s invisible ultraviolet radiation to visible red light. Infrared observations indicate that this nebula may contain complex carbon molecules known as PAHs. At the estimated distance of the Iris Nebula this remarkable wide field view is over 30 light-years across.
2009.06.12: SNR 0104: An Unusual Suspect
SNR 0104 is a supernova remnant with an unusual shape. Found 190,000 light-years away in our neighboring galaxy the Small Magellanic Cloud, SNR 0104 is suspected of being the expanding debris cloud from a Type 1a supernova – the catastrophic thermonuclear explosion of a white dwarf star. For example, like Type 1a supernova remnants within our galaxy, investigations show that it contains large amounts of iron. But unlike other Type 1a remnants, including the well-studied Tycho, Kepler, and SN 1006, SNR 0104 is definitely not spherical. In fact, the remnant’s shape suggests this supernova explosion was very asymmetric and produced strong jets. This intriguing composite image combines Chandra Observatory x-ray data of the remnant, shown in purple hues, with Spitzer Space Telescope infrared data covering the wider region, mapped to red and green colors. It indicates that the supernova explosion took place in the complicated and dense environment of a star-forming region. So, an alternative explanation is that the expanding debris cloud is sweeping up clumpy interstellar material, accounting for the odd shape. The broad, multiwavelength view spans about 1,800 light-years at the estimated distance of SNR 0104.
Inspired by the night skies of planet Earth in the International Year of Astronomy, photographer Larry Landolfi created this tantalizing fantasy view. The composited image suggests a luminous Milky Way is the heavenly extension of a country road. Of course, the name for our galaxy, the Milky Way (in Latin, Via Lactea), does refer to its appearance as a milky band or path in the sky. In fact, the word galaxy itself derives from the Greek for milk. Visible on moonless nights from dark sky areas, though not so bright or colorful as in this image, the glowing celestial band is due to the collective light of myriad stars along the plane of our galaxy, too faint to be distinguished individually. The diffuse starlight is cut by dark swaths of obscuring galactic dust clouds. Four hundred years ago, Galileo turned his telescope on the Milky Way and announced it to be „… a congeries of innumerable stars …“
2009.06.12: Clematis montana var. wilsonii
Plant Family / Families: Ranunculaceae
Scientific Name and Author: Clematis montana Buch.-Ham. ex DC. var. wilsonii Sprague
Clematis montana var. wilsonii commemorates E.H. (Chinese) Wilson (1876-1930), who introduced vast numbers of plants to cultivation, primarily from China and Japan. This variety from southwestern China is less well known than the more commonly cultivated selections of Clematis montana var. rubens (which are generally larger and pink). Most references describe var. wilsonii as late-flowering (mid to late June) and strongly fragrant, smelling of hot chocolate. The aroma to me is considerably more complex, especially when smelled at close range. A number of my colleagues have been debating the particular components of the aroma—what else do staff at a botanical garden do at lunch?—and we’ve come up with quite a list, including chocolate (of course), but also peppermint, cinnamon, cardamom, carob bean, narcissus (the large trumpet types), oaked Chardonnay, and Advocaat liqueur—the more elusive and volatile components being expressed more strongly with older flowers. Our plants came to us from Guernsey Clematis, the famous nursery founded by plantsman Raymond Evison.
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