- The largest photomosaic of the Andromeda galaxy was created with 600 images from the Hubble space telescope.
- The image resolves 200 million stars, all brighter than our sun. We can also see star clouds, dust lanes and even background galaxies peeking through.
- The image gives us insight into Andromeda’s history. It reveals that Andromeda had more active recent star-formation and interaction with other galaxies than the Milky Way.
NASA/ESA posted this original article on January 16, 2025. Edits by EarthSky.
Andromeda in the largest photomosaic from Hubble
On January 16, 2025, NASA and ESA unveiled the largest photomosaic of the Andromeda galaxy, assembled from Hubble Space Telescope observations. Hubble took more than 10 years to collect data for this colorful portrait of our neighboring galaxy. The mosaic consists of more than 600 snapshots. This stunning, colorful mosaic captures the glow of 200 million stars, spread across roughly 2.5 billion pixels.
In the years following the launch of the NASA/ESA Hubble Space Telescope, astronomers have tallied over 1 trillion galaxies in the universe. But only one galaxy stands out as the most important nearby stellar island to our Milky Way: the magnificent Andromeda galaxy (Messier 31). You can see it with the unaided eye from a dark sky on a clear autumn night. It looks like a faint cigar-shaped object roughly the apparent angular diameter of our moon.
A century ago, Edwin Hubble first established that this so-called “spiral nebula” was actually far outside our own Milky Way galaxy, at a distance of approximately 2.5 million light-years, or roughly 25 Milky Way diameters. Prior to that, astronomers had long thought that the Milky Way encompassed the entire universe. Overnight, Hubble’s discovery turned cosmology upside down by unveiling an infinitely grander universe.
Now, a century later, the space telescope named for Hubble has accomplished the most comprehensive survey of this enticing empire of stars. The Hubble telescope is yielding new clues to the evolutionary history of Andromeda, and it looks markedly different from the Milky Way’s history.
A Herculean task
Without Andromeda as a proxy for spiral galaxies in the universe at large, astronomers would know much less about the structure and evolution of our own Milky Way. That’s because we are embedded inside the Milky Way.
Hubble’s sharp imaging capabilities can resolve more than 200 million stars in the Andromeda galaxy, detecting only stars brighter than our sun. They look like grains of sand across the beach. But that’s just the tip of the iceberg. Astronomers estimate Andromeda’s total population at around 1 trillion stars, with many less massive stars falling below Hubble’s sensitivity limit.
Photographing Andromeda was a Herculean task because the galaxy is a much bigger target on the sky than the galaxies Hubble routinely observes, which are often billions of light-years away. The full mosaic was carried out under two Hubble observing programs. In total it required over 1,000 Hubble orbits, spanning more than a decade.
This panorama started with the Panchromatic Hubble Andromeda Treasury (PHAT) program about a decade ago. It included images in near-ultraviolet, visible and near-infrared wavelengths. Scientists used the Advanced Camera for Surveys and the Wide Field Camera aboard Hubble to photograph the northern half of Andromeda.
Following this was the Panchromatic Hubble Andromeda Southern Treasury (PHAST). It added images of approximately 100 million stars in the southern half of Andromeda. This region is structurally unique and more sensitive to the galaxy’s merger history than the northern disk mapped by the PHAT survey.
The combined programs collectively cover the entire disk of Andromeda. Andromeda tilts by 77 degrees relative to Earth’s view. The galaxy is so large that the mosaic used approximately 600 separate fields of view. The mosaic image consists of at least 2.5 billion pixels.
Hubble traces hidden history of the Andromeda galaxy
The complementary Hubble survey programs provide information about the age, heavy-element abundance and stellar masses inside Andromeda. This will allow astronomers to distinguish between competing scenarios where Andromeda merged with one or more galaxies. Hubble’s detailed measurements constrain models of Andromeda’s merger history and disk evolution.
Though the Milky Way and Andromeda formed presumably around the same time many billions of years ago, observational evidence shows they have very different evolutionary histories, despite growing up in the same cosmological neighborhood. Andromeda seems to be more highly populated with younger stars and unusual features like coherent streams of stars, say researchers. This implies it has a more active recent star-formation and interaction history than the Milky Way.
A possible culprit is the compact satellite galaxy Messier 32, which resembles the stripped-down core of a once-spiral galaxy that may have interacted with Andromeda in the past. Computer simulations suggest that when a close encounter with another galaxy uses up all the available interstellar gas, star formation subsides.
Bottom line: Astronomers have created the largest photomosaic of the Andromeda galaxy yet using Hubble data.
The post Andromeda galaxy: Hubble’s largest photomosaic yet first appeared on EarthSky.
from EarthSky https://ift.tt/mcdUuw8
- The largest photomosaic of the Andromeda galaxy was created with 600 images from the Hubble space telescope.
- The image resolves 200 million stars, all brighter than our sun. We can also see star clouds, dust lanes and even background galaxies peeking through.
- The image gives us insight into Andromeda’s history. It reveals that Andromeda had more active recent star-formation and interaction with other galaxies than the Milky Way.
NASA/ESA posted this original article on January 16, 2025. Edits by EarthSky.
Andromeda in the largest photomosaic from Hubble
On January 16, 2025, NASA and ESA unveiled the largest photomosaic of the Andromeda galaxy, assembled from Hubble Space Telescope observations. Hubble took more than 10 years to collect data for this colorful portrait of our neighboring galaxy. The mosaic consists of more than 600 snapshots. This stunning, colorful mosaic captures the glow of 200 million stars, spread across roughly 2.5 billion pixels.
In the years following the launch of the NASA/ESA Hubble Space Telescope, astronomers have tallied over 1 trillion galaxies in the universe. But only one galaxy stands out as the most important nearby stellar island to our Milky Way: the magnificent Andromeda galaxy (Messier 31). You can see it with the unaided eye from a dark sky on a clear autumn night. It looks like a faint cigar-shaped object roughly the apparent angular diameter of our moon.
A century ago, Edwin Hubble first established that this so-called “spiral nebula” was actually far outside our own Milky Way galaxy, at a distance of approximately 2.5 million light-years, or roughly 25 Milky Way diameters. Prior to that, astronomers had long thought that the Milky Way encompassed the entire universe. Overnight, Hubble’s discovery turned cosmology upside down by unveiling an infinitely grander universe.
Now, a century later, the space telescope named for Hubble has accomplished the most comprehensive survey of this enticing empire of stars. The Hubble telescope is yielding new clues to the evolutionary history of Andromeda, and it looks markedly different from the Milky Way’s history.
A Herculean task
Without Andromeda as a proxy for spiral galaxies in the universe at large, astronomers would know much less about the structure and evolution of our own Milky Way. That’s because we are embedded inside the Milky Way.
Hubble’s sharp imaging capabilities can resolve more than 200 million stars in the Andromeda galaxy, detecting only stars brighter than our sun. They look like grains of sand across the beach. But that’s just the tip of the iceberg. Astronomers estimate Andromeda’s total population at around 1 trillion stars, with many less massive stars falling below Hubble’s sensitivity limit.
Photographing Andromeda was a Herculean task because the galaxy is a much bigger target on the sky than the galaxies Hubble routinely observes, which are often billions of light-years away. The full mosaic was carried out under two Hubble observing programs. In total it required over 1,000 Hubble orbits, spanning more than a decade.
This panorama started with the Panchromatic Hubble Andromeda Treasury (PHAT) program about a decade ago. It included images in near-ultraviolet, visible and near-infrared wavelengths. Scientists used the Advanced Camera for Surveys and the Wide Field Camera aboard Hubble to photograph the northern half of Andromeda.
Following this was the Panchromatic Hubble Andromeda Southern Treasury (PHAST). It added images of approximately 100 million stars in the southern half of Andromeda. This region is structurally unique and more sensitive to the galaxy’s merger history than the northern disk mapped by the PHAT survey.
The combined programs collectively cover the entire disk of Andromeda. Andromeda tilts by 77 degrees relative to Earth’s view. The galaxy is so large that the mosaic used approximately 600 separate fields of view. The mosaic image consists of at least 2.5 billion pixels.
Hubble traces hidden history of the Andromeda galaxy
The complementary Hubble survey programs provide information about the age, heavy-element abundance and stellar masses inside Andromeda. This will allow astronomers to distinguish between competing scenarios where Andromeda merged with one or more galaxies. Hubble’s detailed measurements constrain models of Andromeda’s merger history and disk evolution.
Though the Milky Way and Andromeda formed presumably around the same time many billions of years ago, observational evidence shows they have very different evolutionary histories, despite growing up in the same cosmological neighborhood. Andromeda seems to be more highly populated with younger stars and unusual features like coherent streams of stars, say researchers. This implies it has a more active recent star-formation and interaction history than the Milky Way.
A possible culprit is the compact satellite galaxy Messier 32, which resembles the stripped-down core of a once-spiral galaxy that may have interacted with Andromeda in the past. Computer simulations suggest that when a close encounter with another galaxy uses up all the available interstellar gas, star formation subsides.
Bottom line: Astronomers have created the largest photomosaic of the Andromeda galaxy yet using Hubble data.
The post Andromeda galaxy: Hubble’s largest photomosaic yet first appeared on EarthSky.
from EarthSky https://ift.tt/mcdUuw8
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