Tag Archives: Milky Way

Do we matter in the cosmos?

By Nick Hughes – By recent estimates, the Milky Way is just one of 2 trillion galaxies in the observable Universe, and the region of space that they occupy spans at least 90 billion light-years.

If you imagine Earth shrunk down to the size of a single grain of sand, and you imagine the size of that grain of sand relative to the entirety of the Sahara Desert, you are still nowhere near to comprehending how infinitesimally small a position we occupy in space.

And that’s just the spatial dimension. The observable Universe has existed for around 13.8 billion years. If we shrink that span of time down to a single year, with the Big Bang occurring at midnight on 1 January, the first Homo sapiens made an appearance at 22:24 on 31 December. It’s now 23:59:59, as it has been for the past 438 years, and at the rate we’re going it’s entirely possible that we’ll be gone before midnight strikes again.

In the grand scheme of things we are very, very small. more> https://goo.gl/Dp2NaC

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Hubble Images a Dusty Galaxy, Home to an Exploding Star

NASA – The galaxy pictured here is NGC 4424, located in the constellation of Virgo. It is not visible with the naked eye but has been captured here with the NASA/ESA Hubble Space Telescope.

Although it may not be obvious from this image, NGC 4424 is in fact a spiral galaxy. In this image it is seen more or less edge on, but from above, you would be able to see the arms of the galaxy wrapping around its center to give the characteristic spiral form.

In 2012, astronomers observed a supernova in NGC 4424 — a violent explosion marking the end of a star’s life. During a supernova explosion, a single star can often outshine an entire galaxy. However, the supernova in NGC 4424, dubbed SN 2012cg, cannot be seen here as the image was taken ten years prior to the explosion. Along the central region of the galaxy, clouds of dust block the light from distant stars and create dark patches.

To the left of NGC 4424 there are two bright objects in the frame. The brightest is another, smaller galaxy known as LEDA 213994 and the object closer to NGC 4424 is an anonymous star in our Milky Way.

European Space Agency

Credit: ESA/Hubble & NASA, Acknowledgement: Gilles Chapdelaine

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Hubble’s View of the Polar Ring of Arp 230

NASA – This image shows Arp 230, also known as IC 51, observed by the NASA/ESA Hubble Space Telescope.

Arp 230 is a galaxy of an uncommon or peculiar shape, and is therefore part of the Atlas of Peculiar Galaxies produced by Halton Arp. Its irregular shape is thought to be the result of a violent collision with another galaxy sometime in the past. The collision could also be held responsible for the formation of the galaxy’s polar ring.

The outer ring surrounding the galaxy consists of gas and stars and rotates over the poles of the galaxy. It is thought that the orbit of the smaller of the two galaxies that created Arp 230 was perpendicular to the disk of the second, larger galaxy when they collided. In the process of merging the smaller galaxy would have been ripped apart and may have formed the polar ring structure astronomers can observe today.

Arp 230 is quite small for a lenticular galaxy, so the two original galaxies forming it must both have been smaller than the Milky Way. A lenticular galaxy is a galaxy with a prominent central bulge and a disk, but no clear spiral arms. They are classified as intermediate between an elliptical galaxy and a spiral galaxy.

European Space Agency / Image Credit: ESA/Hubble & NASA, Acknowledgement: Flickr user Det58

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Hubble Sees Turquoise-Tinted Plumes in Large Magellanic Cloud

NASA – The brightly glowing plumes seen in this image are reminiscent of an underwater scene, with turquoise-tinted currents and nebulous strands reaching out into the surroundings.

However, this is no ocean. This image actually shows part of the Large Magellanic Cloud (LMC), a small nearby galaxy that orbits our galaxy, the Milky Way, and appears as a blurred blob in our skies. The NASA/European Space Agency (ESA) Hubble Space Telescope has peeked many times into this galaxy, releasing stunning images of the whirling clouds of gas and sparkling stars (opo9944a, heic1301, potw1408a).

This image shows part of the Tarantula Nebula’s outskirts. This famously beautiful nebula, located within the LMC, is a frequent target for Hubble (heic1206, heic1402).

In most images of the LMC the color is completely different to that seen here. This is because, in this new image, a different set of filters was used. The customary R filter, which selects the red light, was replaced by a filter letting through the near-infrared light. In traditional images, the hydrogen gas appears pink because it shines most brightly in the red. Here however, other less prominent emission lines dominate in the blue and green filters.

This data is part of the Archival Pure Parallel Project (APPP), a project that gathered together and processed over 1,000 images taken using Hubble’s Wide Field Planetary Camera 2, obtained in parallel with other Hubble instruments. Much of the data in the project could be used to study a wide range of astronomical topics, including gravitational lensing and cosmic shear, exploring distant star-forming galaxies, supplementing observations in other wavelength ranges with optical data, and examining star populations from stellar heavyweights all the way down to solar-mass stars.

Image Credit: ESA/Hubble & NASA: acknowledgement: Josh Barrington
Text: European Space Agency

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Milky Way Viewed From the International Space Station

NASA – NASA astronaut Reid Wiseman captured this image from the International Space Station and posted it to social media on Sept. 28, 2014, writing, “The Milky Way steals the show from Sahara sands that make the Earth glow orange.”

Aboard the space station, the six-person Expedition 41 crew is currently preparing for two spacewalks set for Oct. 7 and 15. During the first six-and-a-half-hour spacewalk, slated to begin on Oct. 7 around 8:10 a.m. EDT, Wiseman and European Space Agency astronaut Alexander Gerst will transfer a previously uninstalled pump module from its temporary stowage location to the External Stowage Platform-2. The two spacewalkers also will install the Mobile Transporter Relay Assembly that adds the capability to provide “keep-alive” power to the system that moves the station’s robotic arm between worksites. NASA astronaut Barry Wilmore will join Wiseman for the second Expedition 41 spacewalk on Oct. 15.

Image Credit: NASA/Reid Wiseman

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NASA Engineers Conduct Low Light Test on New Technology for Webb Telescope

NASA – NASA engineers inspect a new piece of technology developed for the James Webb Space Telescope, the micro shutter array, with a low light test at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Developed at Goddard to allow Webb’s Near Infrared Spectrograph to obtain spectra of more than 100 objects in the universe simultaneously, the micro shutter array uses thousands of tiny shutters to capture spectra from selected objects of interest in space and block out light from all other sources.

The James Webb Space Telescope is a large space telescope, optimized for infrared wavelengths. It is scheduled for launch later in this decade. Webb will find the first galaxies that formed in the early universe, connecting the Big Bang to our own Milky Way galaxy. Webb will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own solar system.

Caption Credit: Laura Betz, NASA’s Goddard Space Flight Center, Greenbelt, Maryland. Image Credit: NASA Goddard/Chris Gunn

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Hubble’s Messier 5

NASA – “Beautiful Nebula discovered between the Balance [Libra] & the Serpent [Serpens] …” begins the description of the 5th entry in 18th century astronomer Charles Messier’s famous catalog of nebulae and star clusters.

Though it appeared to Messier to be fuzzy and round and without stars, Messier 5 (M5) is now known to be a globular star cluster, 100,000 stars or more, bound by gravity and packed into a region around 165 light-years in diameter. It lies some 25,000 light-years away.

Roaming the halo of our galaxy, globular star clusters are ancient members of the Milky Way. M5 is one of the oldest globulars, its stars estimated to be nearly 13 billion years old.

The beautiful star cluster is a popular target for Earthbound telescopes. Of course, deployed in low Earth orbit on April 25, 1990, the Hubble Space Telescope has also captured its own stunning close-up view that spans about 20 light-years near the central region of M5.

Even close to its dense core at the left, the cluster’s aging red and blue giant stars and rejuvenated blue stragglers stand out in yellow and blue hues in the sharp color image.

Image Credit: NASA, Hubble Space Telescope, ESA

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The Shocking Behavior of a Speedy Star

NASA – Roguish runaway stars can have a big impact on their surroundings as they plunge through the Milky Way galaxy. Their high-speed encounters shock the galaxy, creating arcs, as seen in this newly released image from NASA’s Spitzer Space Telescope.

In this case, the speedster star is known as Kappa Cassiopeiae, or HD 2905 to astronomers. It is a massive, hot supergiant moving at around 2.5 million mph relative to its neighbors (1,100 kilometers per second). But what really makes the star stand out in this image is the surrounding, streaky red glow of material in its path. Such structures are called bow shocks, and they can often be seen in front of the fastest, most massive stars in the galaxy.

Bow shocks form where the magnetic fields and wind of particles flowing off a star collide with the diffuse, and usually invisible, gas and dust that fill the space between stars. How these shocks light up tells astronomers about the conditions around the star and in space. Slow-moving stars like our sun have bow shocks that are nearly invisible at all wavelengths of light, but fast stars like Kappa Cassiopeiae create shocks that can be seen by Spitzer’s infrared detectors.

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Crab Nebula, as Seen by Herschel and Hubble

NASA – This image shows a composite view of the Crab nebula, an iconic supernova remnant in our Milky Way galaxy, as viewed by the Herschel Space Observatory and the Hubble Space Telescope. Herschel is a European Space Agency (ESA) mission with important NASA contributions, and Hubble is a NASA mission with important ESA contributions.

A wispy and filamentary cloud of gas and dust, the Crab nebula is the remnant of a supernova explosion that was observed by Chinese astronomers in the year 1054.

The image combines Hubble’s view of the nebula at visible wavelengths, obtained using three different filters sensitive to the emission from oxygen and sulphur ions and is shown here in blue. Herschel’s far-infrared image reveals the emission from dust in the nebula and is shown here in red.

While studying the dust content of the Crab nebula with Herschel, a team of astronomers have detected emission lines from argon hydride, a molecular ion containing the noble gas argon. This is the first detection of a noble-gas based compound in space.

The Herschel image is based on data taken with the Photoconductor Array Camera and Spectrometer (PACS) instrument at a wavelength of 70 microns; the Hubble image is based on archival data from the Wide Field and Planetary Camera 2 (WFPC2).

Image credit: ESA/Herschel/PACS/MESS Key Programme Supernova Remnant Team; NASA, ESA and Allison Loll/Jeff Hester (Arizona State University)

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Hubble Sees Anemic Spiral NGC 4921

NASA – How far away is spiral galaxy NGC 4921? Although presently estimated to be about 310 million light years distant, a more precise determination could be coupled with its known recession speed to help humanity better calibrate the expansion rate of the entire visible universe. Toward this goal, several images were taken by the Hubble Space Telescope in order to help identify key stellar distance markers known as Cepheid variable stars. Since NGC 4921 is a member of the Coma Cluster of Galaxies, refining its distance would also allow a better distance determination to one of the largest nearby clusters in the local universe. The magnificent spiral NGC 4921 has been informally dubbed anemic because of its low rate of star formation and low surface brightness. Visible in the above image are, from the center, a bright nucleus, a bright central bar, a prominent ring of dark dust, blue clusters of recently formed stars, several smaller companion galaxies, unrelated galaxies in the far distant universe, and unrelated stars in our Milky Way Galaxy.

Image Credit: Hubble Legacy Archive, ESA, NASA