Astronomy Picture of the Day | A rose made of galaxies

Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

This image of a pair of interacting galaxies called Arp 273 was released to celebrate the 21st anniversary of the launch of the NASA/ESA Hubble Space Telescope.

The distorted shape of the larger of the two galaxies shows signs of tidal interactions with the smaller of the two. It is thought that the smaller galaxy has actually passed through the larger one.

via spacetelescope.org
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Astronomy Picture of the Day – A Lunar Eclipse on Solstice Day

A Lunar Eclipse on Solstice Day
Credit & Copyright: Jerry Lodriguss
(Catching the Light)

Astronomy Picture of the Day | Mirach's Ghost


Mirach’s Ghost

Credit & Copyright: Anthony Ayiomamitis (TWAN)

Explanation: As far as ghosts go, Mirach’s Ghost isn’t really that scary. In fact, Mirach’s Ghost is just a faint, fuzzy galaxy, well known to astronomers, that happens to be seen nearly along the line-of-sight to Mirach, a bright star. Centered in this star field, Mirach is also called Beta Andromedae. About 200 light-years distant, Mirach is a red giant star, cooler than the Sun but much larger and so intrinsically much brighter than our parent star. In most telescopic views, glare and diffraction spikes tend to hide things that lie near Mirach and make the faint, fuzzy galaxy look like a ghostly internal reflection of the almost overwhelming starlight. Still, appearing in this sharp image just above and to the right of Mirach, Mirach’s Ghost is cataloged as galaxy NGC 404 and is estimated to be some 10 million light-years away.

Credit: Mac Hunter

Mirach’s ghost is, in itself, not a very interesting galaxy. A small plain looking E-S0 type galaxy. However, its postion about 7 arc minutes from the 2nd magnitude M0 star beta And – known as Mirach – makes it into an interesting photographic target.

Astronomy Picture Of The Day | NGC 2683: Spiral Edge-On

NGC 2683: Spiral Edge-On

Credit: Data: Hubble Legacy Archive, ESA, NASA; Processing: Nikolaus Sulzenauer

Explanation: Does spiral galaxy NGC 2683 have a bar across its center? Being so nearly like our own barred Milky Way Galaxy, one might guess it has. Being so nearly edge-on, however, it is hard to tell. Either way, this gorgeous island universe, cataloged as NGC 2683, lies a mere 20 million light-years distant in the northern constellation of the Cat (Lynx). NGC 2683 is seen nearly edge-on in this cosmic vista, with more distant galaxies scattered in the background. Blended light from a large population of old yellowish stars forms the remarkably bright galactic core. Starlight silhouettes the dust lanes along winding spiral arms, dotted with the telltale blue glow of young star clusters in this galaxy‘s star forming regions.

NGC 2683 was discovered by William Herschel on February 5, 1788.

This spiral galaxy is viewed nearly edge-on from our perspective. Because of its appearance, it was nicknamed the “UFO Galaxy” by the Astronaut Memorial Planetarium and Observatory site. Note the small yellowish core in the center of the galaxy, consisting of older stars. Also note the fine details of the spiral structure, traced by dark dust in the brighter part of the disk (particularly well visible in the larger image.

The UFO is receding from us at 410 km/s, and from the Galactic Center at 375 km/s. This indicates that it is probably one of the nearby galaxies, perhaps at about 16 million light years.

The image in this page was obtained by Dick Stone when participating in the Kitt Peak Visitor Center’s Advanced Observing Program. It is a composite of 4 CCD images: Luminance = 42 min, Red = 20 min, Green = 20 min, Blue = 40 min.

via apod.nasa.gov

Astronomy Picture Of The Day | Melotte 15 in the Heart

Melotte 15 in the Heart Image Credit & Copyright: Derek Santiago

Explanation: Cosmic clouds seem to form fantastic shapes in the central regions of emission nebula IC 1805. Of course, the clouds are sculpted by stellar winds and radiation from massive hot stars in the nebula‘s newborn star cluster, Melotte 15. About 1.5 million years young, the cluster stars are near the center in this colorful skyscape, along with dark dust clouds silhouetted against glowing atomic gas. A composite of narrow and broad band telescopic images, the view spans about 40 light-years and includes emission from hydrogen in green, sulfur in red, and oxygen in blue hues. Wider field images reveal that IC 1805’s simpler, overall outline suggests its popular name – The Heart Nebula. IC 1805 is located about 7,500 light years away toward the constellation Cassiopeia.

Astronomy Picture of the Day | NASA's Hubble Harvests Distant Solar System Objects

Beyond the orbit of Neptune reside countless icy rocks known as trans-Neptunian objects (TNOs). One of the biggest, Pluto, is classified as a dwarf planet. The region also supplies us with comets such as famous Comet Halley. Most TNOs are small and receive little sunlight, making them faint and difficult to spot.

This is an artist’s concept of a craggy piece of Solar System debris that belongs to a class of bodies called trans-Neptunian objects (TNOs). Credit: NASA, ESA, and G. Bacon (STScI)

Now, astronomers using clever techniques to cull the data archives of NASA’s Hubble Space Telescope have added 14 new TNOs to the catalog. Their method promises to turn up hundreds more.

“Trans-Neptunian objects interest us because they are building blocks left over from the formation of the solar system,” explained lead author Cesar Fuentes, formerly with the Harvard-Smithsonian Center for Astrophysics and now at Northern Arizona University.

As TNOs slowly orbit the sun, they move against the starry background, appearing as streaks of light in time exposure photographs. The team developed software to analyze hundreds of Hubble images hunting for such streaks. After promising candidates were flagged, the images were visually examined to confirm or refute each discovery.

Most TNOs are located near the ecliptic — a line in the sky marking the plane of the solar system (since the solar system formed from a disk of material). Therefore, the team searched within 5 degrees of the ecliptic to increase their chance of success.

They found 14 objects, including one binary (two TNOs orbiting each other like a miniature Pluto-Charon system). All were very faint, with most measuring magnitude 25-27 (more than 100 million times fainter than objects visible to the unaided eye).

By measuring their motion across the sky, astronomers calculated an orbit and distance for each object. Combining the distance and brightness (plus an assumed albedo or reflectivity), they then estimated the size. The newfound TNOs range from 25 to 60 miles (40-100 km) across.

Unlike planets, which tend to have very flat orbits (known as low inclination), some TNOs have orbits significantly tilted from the ecliptic (high inclination). The team examined the size distribution of TNOs with low- versus high-inclination orbits to gain clues about how the population has evolved over the past 4.5 billion years.

Generally, smaller trans-Neptunian objects are the shattered remains of bigger TNOs. Over billions of years, these objects smack together, grinding each other down. The team found that the size distribution of TNOs with low- versus high-inclination orbits is about the same as objects get fainter and smaller. Therefore, both populations (low and high inclination) have similar collisional histories.

This initial study examined only one-third of a square degree of the sky, meaning that there is much more area to survey. Hundreds of additional TNOs may lurk in the Hubble archives at higher ecliptic latitudes. Fuentes and his colleagues intend to continue their search.

“We have proven our ability to detect and characterize TNOs even with data intended for completely different purposes,” Fuentes said.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

 

Astronomy Picture Of The Day | GRO J1655-40: Evidence for a Spinning Black Hole

GRO J1655-40: Evidence for a Spinning Black Hole
Credit: April Hobart, CXC

Explanation: In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes. The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickering at a rate of 450 times a second. Given a previous mass estimate for the central object of seven times the mass of our Sun, the rate of the fast flickering can be explained by a black hole that is rotating very rapidly. What physical mechanisms actually cause the flickering — and a slower quasi-periodic oscillation (QPO) — in accretion disks surrounding black holes and neutron stars remains a topic of much research.