Messier 57

ring_nebulaThe Hubble Space Telescope took a look down a barrel of gas cast off by a dying star thousands of years ago. The resulting photo reveals elongated dark clumps of material embedded in the gas at the edge of the nebula and the dying central star floating in a blue haze of hot gas. This ring nebula (aka Messier 57) is about a light-year in diameter and around 2,000 light-years from Earth in the constellation Lyra. The colors shown in this image are roughly true colors. The image was assembled from three black-and-white photos taken through different color filters. Blue emissions come from very hot helium mostly located near the hot central star. Green is from ionized oxygen found farther out. Red comes from ionized nitrogen farthest from the star. The gases glow because it is excited ultraviolet radiation from the star whose surface temperature is estimated to be over 100,000 °C.

Image Credit: NASA / ESA

A Crowded Neighborhood

m60The densest galaxy in the nearby Universe may be this galaxy known as M60-UCD1. It is located near a massive elliptical galaxy called M60, about 54 million light years from Earth. Packed with an extraordinary number of stars, M60-UCD1 is an “ultra-compact dwarf galaxy”. It was discovered with the Hubble Space Telescope and follow-up observations were done with the Chandra X-ray Observatory and ground-based optical telescopes. It is the most luminous known galaxy of its type and one of the most massive, weighing 200 million times more than our Sun.

This composite image shows the region near M60. Data from the Chandra X-ray Observatory are pink and data from the Hubble Space Telescope are red, green and blue. The Chandra image shows hot gas and double stars containing black holes and neutron stars and the Hubble image reveals stars in M60 at the right edge of the frame.

Image Credit: NASA

36 Galactic Mile Posts

These 36 galaxies are some of the 40+ that have been observed by astronomers using the Hubble Space Telescope because they contain both Cepheid variable stars and supernovae. These stars are used measure the distance and refine the measurement of the rate of the expansion of the universe. Pictured above (from left to right and top to bottom) are NGC 7541, NGC 3021, NGC 5643, NGC 3254, NGC 3147, NGC 105, NGC 2608, NGC 3583, NGC 3147, Mrk 1337, NGC 5861, NGC 2525, NGC 1015, UGC 9391, NGC 691, NGC 7678, NGC 2442, NGC 5468, NGC 5917, NGC 4639, NGC 3972, The Antennae Galaxies, NGC 5584, M106, NGC 7250, NGC 3370, NGC 5728, NGC 4424, NGC 1559, NGC 3982, NGC 1448, NGC 4680, M101, NGC 1365, NGC 7329, and NGC 3447.

Image Credits: NASA / ESA / STScI

NGC 1512

NGC 1512 is a barred spiral galaxy around 38 million light-years from Earth in the constellation Horologium. It has a double ring structure with a so-called nuclear ring around the galactic nucleus and a second ring further out in the main disk. When viewed in UV light, the galaxy shows at least 200 clusters recent star formation activity.

Image Credit: NASA / ESA

The Storm Around Saturn’s North Pole

Saturn_hurricane1The Cassini spacecraft relayed to Earth thist close-up, visible-light views of a monster hurricane swirling around Saturn’s north pole. It’s 2,000 km wide, 20 times larger than the average hurricane eye on Earth. The clouds at the outer edge of the hurricane are moving at 150 meters per second as the storm swirls inside a large, six-sided weather pattern known as the hexagon. This false-color image highlights the storm at Saturn’s north pole.

Saturn_hurricane3A natural color image is at left.

Hurricanes on Earth feed off warm ocean water, but there is no body of water on Saturn. Learning how these Saturnian storms use water vapor might tell scientists more about how terrestrial hurricanes are generated and sustained. Both terrestrial hurricanes and Saturn’s north polar vortex have a central eye with no clouds or very low clouds. Both have high clouds forming an eye wall, other high clouds spiraling around the eye, and a counter-clockwise spin in the northern hemisphere. But the one on Saturn is much bigger than its counterparts on Earth and spins surprisingly fast. On Saturn, the wind in the eye wall blows more than four times faster than hurricane-force winds on Earth. Terrestrial hurricanes move around, but Saturn’s hurricane is parked over the planet’s north pole. On Earth, hurricanes tend to drift northward because of the forces acting on the winds as the planet rotates. Saturn’s does not drift; it’s already as far north as it can be.

Saturn_hurricane2Scientists believe the massive storm has been churning for years. When Cassini arrived in the Saturn system in 2004, Saturn’s north pole was in winter darkness. Cassini‘s composite infrared spectrometer and visual and infrared mapping spectrometer detected the great vortex, but a visible-light image had to wait for the equinox in 2009 when sunlight begin falling on the higher latitudes of Saturn’s northern hemisphere.

Image Credits: NASA

A Bright Pearl

A hazy nebulaThis is a false color image from Hubble’s Wide Field Planetary Camera 2 of NGC 1501, a complex planetary nebula located in the constellation of Camelopardalis (The Giraffe). NGC 1501 is a planetary nebula that is just under 5,000 light-years away from us. It has a central star shining brightly from within the nebula’s cloud. This bright pearl embedded in its glowing shell gives rise to the nebula’s popular nickname—the Oyster Nebula.

While NGC 1501’s central star blasted off its outer shell long ago, it still remains very hot and luminous, but it can be difficult to spot through modest telescopes. The star seems to be pulsating, varying quite significantly in brightness over a timescale of just half an hour. While variable stars are not unusual, it is unusual to find one at the heart of a planetary nebula.

Image Credit: ESA / NASA

An Irregular Dwarf

content/uploads/2015/04/i_zwicky_18.jpg”>I_Zwicky_18I Zwicky 18 is a dwarf irregular galaxy located about 59 million light years away. Spectroscopic observations with ground-based telescopes showed that I Zwicky 18 to be almost completely made up of hydrogen and helium, the main ingredients created in the Big Bang, and galaxies with I Zwicky 18’s youthful appearance are typically found only in the early universe. Initial observations with the Hubble Space Telescope suggested an age of 500 million years, but later Hubble observations found faint, older stars in the galaxy, suggesting its star formation started at least one billion years ago and possibly as much as ten billion years ago. It’s possible that the galaxy may have formed around the same time as most other galaxies.

Image Credit: NASA / ESA