Starship Asterisk*

Credit: NASA/JPL-Caltech/MSSS

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A new self-portrait of NASA's Curiosity Mars rover shows the vehicle on Vera Rubin Ridge, which it has been investigating for the past several months. Directly behind the rover is the start of a clay-rich slope scientists are eager to begin exploring. In coming weeks, Curiosity will begin to climb this slope. In the image, north is on the left and west is on the right, with Gale Crater's rim on the horizon of both edges.

Poking up just behind Curiosity's mast is Mount Sharp, photobombing the robot's selfie. When Curiosity landed on Mars five years ago, the team's intention was to study lower Mount Sharp, where the rover will remain for all of its time on Mars. The mountain's base provides access to layers formed over millions of years. These layers formed in the presence of water -- likely due to a lake or lakes where sediments accumulated, which formed these layers inside Gale Crater.

The mosaic was assembled from dozens of images taken by Curiosity's Mars Hands Lens Imager (MAHLI). They were all taken on Jan. 23, 2018, during Sol 1943.

Click to view full size image 1 or image 2

Credit: ESO/ESA/Hubble & NASA/J. Weaver et al.

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This unusual image reveals the aftermath of a catastrophic collision between two galaxies, which happened about one billion years ago. The result? A single, very oddly shaped galaxy named NGC 7252, and curiously nicknamed the Atoms for Peace galaxy.

At the heart of this merger remnant lies a fascinating “minispiral” — a rotating disc of glowing gas, bursting with star formation. Using the VIsible Multi-Object Spectrograph (VIMOS) instrument on ESO’s Very Large Telescope (VLT), astronomers were able to measure the movement of the gas within this disc, allowing them to map its rotation. Red regions indicate gas moving away from us, and blue regions towards us. Together, these colours reveal the galaxy's steadily rotating centre, as well as highlighting two flowing streams of hot gas north-west and south-east of the central region. Past studies suggested that the central spiral was rotating counter to the rest of the galaxy, but by comparing the movement of stars around the galaxy with the gas ionised by newly formed stars in the minispiral, we now know that they are in fact rotating in the same direction.

Such a detailed map is possible due to the Integral Field Unit (IFU) on VIMOS, allowing astronomers to study the gas in NGC 7252 with a comprehensive "mosaic" view. Much like the way a fly observes the world, an IFU divides its subject into many cells, or pixels, generating a spectrum for every single one. The resulting information is arranged into a 3D data cube, which is particularly useful in studying extended objects in just one shot.

Credit: ESA/Hubble & NASA

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Roughly 50 million light-years away lies a somewhat overlooked little galaxy named NGC 1559. Pictured here by Hubble’s Wide Field Camera 3, this barred spiral lies in the little-observed southern constellation of Reticulum (The Reticule).

NGC 1559 has massive spiral arms chock-full of star formation, and is receding from us at a speed of about 1300 km/s. The galaxy contains the mass of around ten billion Suns — while this may sound like a lot, that is almost 100 times less massive than the Milky Way. Although NGC 1559 appears to sit near one of our nearest neighbours in the sky — the Large Magellanic Cloud (LMC), this is just a trick of perspective. In reality, NGC 1559 is physically nowhere near the LMC in space — in fact, it truly is a loner, lacking the company of any nearby galaxies or membership of any galaxy cluster.

Despite its lack of cosmic companions, when this lonely galaxy has a telescope pointed in its direction, it puts on quite a show! NGC 1559 has hosted a variety of spectacular exploding stars called supernovae, four of which we have observed — in 1984, 1986, 2005, and 2009 (SN 1984J, 1986L, 2005df [a Type Ia], and 2009ib [a Type II-P, with an unusually long plateau]).

NGC 1559 may be alone in space, but we are watching and admiring from far away.

Credit: NASA/JPL-Caltech/Space Science Institute

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In this view, Saturn’s icy moon Rhea passes in front of Titan as seen by NASA’s Cassini spacecraft. Some of the differences between the two large moons are readily apparent. While Rhea is a heavily-cratered, airless world, Titan’s nitrogen-rich atmosphere is even thicker than Earth’s.

This natural color image was taken in visible light with the Cassini narrow-angle camera on Nov. 19, 2009, at a distance of approximately 713,300 miles (1,148,000 kilometers) from Rhea.

bystander wrote:The Loneliest Firework Display
ESA Hubble Picture of the Week | 2018 Feb 05

https://cdn.spacetelescope.org/archives ... w1806a.jpg

Roughly 50 million light-years away lies a somewhat overlooked little galaxy named NGC 1559. Pictured here by Hubble’s Wide Field Camera 3, this barred spiral lies in the little-observed southern constellation of Reticulum (The Reticule).

NGC 1559 has massive spiral arms chock-full of star formation, and is receding from us at a speed of about 1300 km/s. The galaxy contains the mass of around ten billion Suns — while this may sound like a lot, that is almost 100 times less massive than the Milky Way. Although NGC 1559 appears to sit near one of our nearest neighbours in the sky — the Large Magellanic Cloud (LMC), this is just a trick of perspective. In reality, NGC 1559 is physically nowhere near the LMC in space — in fact, it truly is a loner, lacking the company of any nearby galaxies or membership of any galaxy cluster.

Despite its lack of cosmic companions, when this lonely galaxy has a telescope pointed in its direction, it puts on quite a show! NGC 1559 has hosted a variety of spectacular exploding stars called supernovae, four of which we have observed — in 1984, 1986, 2005, and 2009 (SN 1984J, 1986L, 2005df [a Type Ia], and 2009ib [a Type II-P, with an unusually long plateau]).

NGC 1559 may be alone in space, but we are watching and admiring from far away.

Image Credit: ESO/M. Wittkowski (ESO)

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This ghostly image features a distant and pulsating red giant star known as R Sculptoris. Situated 1200 light-years away in the constellation of Sculptor, R Sculptoris is something known as a carbon-rich asymptotic giant branch (AGB) star, meaning that it is nearing the end of its life. At this stage, low- and intermediate-mass stars cool off, create extended atmospheres, and lose a lot of their mass — they are on their way to becoming spectacular planetary nebulae.

While the basics of this mass-loss process are understood, astronomers are still investigating how it begins near the surface of the star. The amount of mass lost by a star actually has huge implications for its stellar evolution, altering its future, and leading to different types of planetary nebulae. As AGB stars end their lives as planetary nebulae, they produce a vast range of elements — including 50% of elements heavier than iron — which are then released into the Universe and used to make new stars, planets, moons, and eventually the building blocks of life.

One particularly intriguing feature of R Sculptoris is its dominant bright spot, which looks to be two or three times brighter than the other regions. The astronomers that captured this wonderful image, using ESO’s Very Large Telescope Interferometer (VLTI), have concluded that R Sculptoris is surrounded by giant “clumps” of stellar dust that are peeling away from the shedding star. This bright spot is, in fact, a region around the star with little to no dust, allowing us to look deeper into the stellar surface.

This image captures an extremely small section of the sky: approximately 20x20 milliarcseconds. For comparison, Jupiter has an angular size of approximately 40 arcseconds.

• Astronomy & Astrophysics 601:A3 (May 2017) DOI: 10.1051/0004-6361/201630214
  arXiv.org > astro-ph > arXiv:1702.02574 > 08 Feb 2017

Credit: ESA/Hubble & NASA, RELICS Acknowledgement: D. Coe et al.

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This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster PLCK G004.5-19.5. It was discovered by the ESA Planck satellite through the Sunyaev-Zel’dovich effect — the distortion of the cosmic microwave background radiation in the direction of the galaxy cluster, by high energy electrons in the intracluster gas. The large galaxy at the centre is the brightest galaxy in the cluster and the dominant object in this image, and above it a thin, curved gravitational lens arc is visible. This is caused by the gravitational forces of the cluster bending the light from stars and galaxies behind it, in a similar way to how a glass lens bends light.

Several stars are visible in front of the cluster — recognisable by their diffraction spikes — but aside from these, all other visible objects are distant galaxies. Their light has become redshifted by the expansion of space, making them appear redder than they actually are. By measuring the amount of redshift, we know that it took more than 5 billion years for the light from this galaxy cluster to reach us. The light of the galaxies in the background had to travel for even longer than that, making this image an extremely old window into the far reaches of the Universe.

This image was taken by Hubble’s Advanced Camera for Surveys (ACS) and Wide-Field Camera 3 (WFC3) as part of an observing programme called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA/ESA/CSA James Webb Space Telescope (JWST) to study.

starsurfer wrote:Cave Nebula (Sh2-155)
https://www.astrobin.com/260706/C/
Copyright: Tommy Nawratil
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