Starship Asterisk*

bystander wrote: ↑Wed Dec 14, 2022 8:39 pm Big Telescope, Bigger Moon
NOIRLab Image of the Week | 2022 Dec 14

Image Credit: M. Hunt/KPNO/NOIRLab/NSF/AURA

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A full Moon is arguably the worst time to do any optical astronomy, whether it’s with a backyard telescope or at Kitt Peak National Observatory (KPNO), a Program of NSF’s NOIRLab, near Tucson, Arizona. But the full Moon does make for a spectacular view to the naked eye and in this shot beautifully illuminates the surrounding desert landscape. Taken from close to Tucson, several tens of miles/kilometers from KPNO, this image appears to show the Nicholas U. Mayall 4-meter Telescope (Mayall 4m) eclipsing nearly half the diameter of the Moon after moonrise. The Mayall telescope is home to the Dark Energy Spectroscopic Instrument (DESI). DESI, led by the US Department of Energy, is acquiring the spectra of tens of millions of galaxies and quasars to construct a 3D map that will reveal the effects of dark energy in the Universe.

This image was taken before the 2022 Contreras Fire, which affected KPNO. Read more here.

bystander wrote: ↑Wed Dec 14, 2022 8:39 pm
Big Telescope, Bigger Moon
NOIRLab Image of the Week | 2022 Dec 14

... Taken from close to Tucson, several tens of miles/kilometers from KPNO ...

Chris Peterson wrote: ↑Wed Dec 14, 2022 11:51 pm
The observatory is said to be 18 stories high, so nominally 200 feet. It subtends about a quarter of a degree. That places the camera 8.7 miles (14 km) away. Give or take.

bystander wrote: ↑Thu Dec 15, 2022 2:24 am

bystander wrote: ↑Wed Dec 14, 2022 8:39 pm
Big Telescope, Bigger Moon
NOIRLab Image of the Week | 2022 Dec 14

... Taken from close to Tucson, several tens of miles/kilometers from KPNO ...

Chris Peterson wrote: ↑Wed Dec 14, 2022 11:51 pm
The observatory is said to be 18 stories high, so nominally 200 feet. It subtends about a quarter of a degree. That places the camera 8.7 miles (14 km) away. Give or take.

I'm not disputing you, but that's a big difference in estimates.

The Carina Nebula is an enormous stellar nursery about 7,500 light-years from Earth in the southern constellation Carina, the Keel.

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Credits: NASA, ESA, A. Kraus (University of Texas at Austin)
Processing: Gladys Kober (NASA/Catholic University of America)

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This sparkling new image depicts a small section of the Carina Nebula, one of the NASA Hubble Space Telescope’s most-imaged objects. The Carina Nebula, NGC 3372, is an enormous cloud of gas and dust home to several massive and bright stars, including at least a dozen that are 50 to 100 times the mass of our Sun. It is an emission nebula, meaning that the intense radiation from its stars ionizes the gas and causes it to glow. That gas is widely and thinly spread out over a large area, earning it the added designation of a diffuse nebula. Carina is a dynamic area of the sky with bursts of star formation occurring alongside star death. As stars form and produce ultraviolet radiation, their stellar winds disperse the gas and dust around them, sometimes forming dark, dusty cloaks and sometimes creating empty patches for the stars to become clearly visible.

To take this image of the Carina Nebula, scientists relied on Hubble’s infrared light imaging capabilities, which detect longer wavelengths of light not scattered by the heavy dust and gas surrounding the stars. This image shows only a small section of the nebula, located near the center in an area with thinner gas. Due to the nebula’s enormous size – about 300 light-years – astronomers can only study it in sections, piecing together the data from separate images to get an understanding of the nebula’s large-scale structure and composition. The Carina Nebula is visible with the unaided eye from Earth’s southern hemisphere.

The Carina Nebula is about 7,500 light-years from Earth in the southern constellation Carina, the Keel. Astronomers have given it many nicknames over the past few hundred years, including the Grand Nebula and the Eta Carinae Nebula for the bright star at its heart. It was originally discovered from the Cape of Good Hope, South Africa by Nicolas Louis de Lacaille in 1752.

Image Credit: NASA, ESA, and D. Jones (University of California, Santa Cruz); Processing: Gladys Kober (NASA/Catholic University of America)

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Against an inky black backdrop, the blue swirls of spiral galaxy NGC 6956 stand out radiantly. NGC 6956 is a barred spiral galaxy, a common type of spiral galaxy with a bar-shaped structure of stars in its center. This galaxy exists 214 million light-years away in the constellation Delphinus.

Scientists used NASA’s Hubble Space Telescope to image NGC 6956 to study its Cepheid variable stars, which are stars that brighten and dim at regular periods. Since the period of Cepheid variable stars is a function of their brightness, scientists can measure how bright these stars appear from Earth and compare it to their actual brightness to calculate their distance. As a result, these stars are extremely useful in determining the distance of cosmic objects, which is one of the hardest pieces of information to measure for extragalactic objects.

This galaxy also contains a Type Ia supernova, which is the explosion of a white dwarf star that was gradually accreting matter from a companion star. Like Cepheid variable stars, the brightness of these types of supernovae and how fast they dim over time enables scientists to calculate their distance. Scientists can use the measurements gleaned from Cepheid variable stars and Type 1a supernovae to refine our understanding of the rate of expansion of the universe, also known as the Hubble Constant.

NGC3314 wrote: ↑Thu Dec 15, 2022 4:37 pm Both the orientation of the lunar disk and the layout of telescopes show that the viewpoint was west (maybe a bit northwest) of Kitt Peak, almost opposite the direction of Tucson. That's about right for pulling off on the shoulder of Arizona highway 86 as it rounds the mountain (it's 11 road miles from the turnoff to the summit); the town of Sells is too far away for that distance estimate.

The background is filled with bright orange-red clouds of varying density. Towards the top-left several large, pale blue stars with prominent cross-shaped spikes are scattered. A small, tadpole-shaped dark patch floats near one of these stars. More of the same dark, dense gas fills the lower-right, resembling black smoke. A bright yellow star and a smaller blue star shine in front of this.

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Image Credit: ESA/Hubble & NASA, R. Sahai

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Just in time for the festive season, this new Picture of the Week from the NASA/ESA Hubble Space Telescope features a glistening scene in holiday red. This image shows a small region of the well-known nebula Westerhout 5, which lies about 7000 light-years from Earth. Suffused with bright red light, this luminous image hosts a variety of interesting features, including a free-floating Evaporating Gaseous Globule (frEGG). The frEGG in this image is the small tadpole-shaped dark region in the upper centre-left. This buoyant-looking bubble is lumbered with two rather uninspiring names — [KAG2008] globule 13 and J025838.6+604259. 

FrEGGs are a particular class of Evaporating Gaseous Globules (EGGs). Both frEGGs and EGGs are regions of gas that are sufficiently dense that they photoevaporate less easily than the less compact gas surrounding them. Photoevaporation occurs when gas is ionised and dispersed away by an intense source of radiation — typically young, hot stars releasing vast amounts of ultraviolet light. EGGs were only identified fairly recently, most notably at the tips of the Pillars of Creation, which were captured by Hubble in iconic images released in 1995. FrEGGs were classified even more recently, and are distinguished from EGGs by being detached and having a distinct ‘head-tail’ shape. FrEGGs and EGGs are of particular interest because their density makes it more difficult for intense UV radiation, found in regions rich in young stars, to penetrate them. Their relative opacity means that the gas within them is protected from ionisation and photoevaporation. This is thought to be important for the formation of protostars, and it is predicted that many FrEGGs and EGGs will play host to the birth of new stars. 

The frEGG in this image is a dark spot in the sea of red light. The red colour is caused by a particular type of light emission known as H-alpha emission. This occurs when a very energetic electron within a hydrogen atom loses a set amount of its energy, causing the electron to become less energetic and this distinctive red light to be released. 

This image shows a spiral galaxy that is dominated by a bright central region. The galaxy has blue-purple hues with orange-red regions filled with stars. Also visible is large diffraction spike, which appears as a star pattern over the central region of the galaxy. Lots of stars and galaxies fill the background scene.

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Image Credit: ESA/Webb, NASA & CSA, L. Armus, A. S. Evans

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This image is dominated by NGC 7469, a luminous, face-on spiral galaxy approximately 90 000 light-years in diameter that lies roughly 220 million light-years from Earth in the constellation Pegasus. Its companion galaxy IC 5283 is partly visible in the lower left portion of this image.

This spiral galaxy has recently been studied as part of the Great Observatories All-sky LIRGs Survey (GOALS) Early Release Science program with the NASA/ESA/CSA James Webb Space Telescope, which aims to study the physics of star formation, black hole growth, and feedback in four nearby, merging luminous infrared galaxies. Other galaxies studied as part of the survey include previous ESA/Webb Pictures of the Month II ZW 096 and IC 1623.

NGC 7469 is home to an active galactic nucleus (AGN), which is an extremely bright central region that is dominated by the light emitted by dust and gas as it falls into the galaxy’s central black hole. This galaxy provides astronomers with the unique opportunity to study the relationship between AGNs and starburst activity because this particular object hosts an AGN that is surrounded by a starburst ring at a distance of a mere 1500 light-years. While NGC 7469 is one of the best studied AGNs in the sky, the compact nature of this system and the presence of a great deal of dust have made it difficult for scientists to achieve both the resolution and sensitivity needed to study this relationship in the infrared. Now, with Webb, astronomers can explore the galaxy’s starburst ring, the central AGN, and the gas and dust in between.

Using Webb’s MIRI, NIRCam and NIRspec instruments to obtain images and spectra of NGC 7469 in unprecedented detail, the GOALS team has uncovered a number of details about the object. This includes very young star-forming clusters never seen before, as well as pockets of very warm, turbulent molecular gas, and direct evidence for the destruction of small dust grains within a few hundred light-years of the nucleus — proving that the AGN is impacting the surrounding interstellar medium. Furthermore, highly ionised, diffuse atomic gas seems to be exiting the nucleus at roughly 6.4 million kilometres per hour — part of a galactic outflow that had previously been identified, but is now revealed in stunning detail with Webb. With analysis of the rich Webb datasets still underway, additional secrets of this local AGN and starburst laboratory are sure to be revealed.

A prominent feature of this image is the striking six-pointed star that perfectly aligns with the heart of NGC 7469. Unlike the galaxy, this is not a real celestial object, but an imaging artifact known as a diffraction spike, caused by the bright, unresolved AGN. Diffraction spikes are patterns produced as light bends around the sharp edges of a telescope. Webb’s primary mirror is composed of hexagonal segments that each contain edges for light to diffract against, giving six bright spikes. There are also two shorter, fainter spikes, which are created by diffraction from the vertical strut that helps support Webb’s secondary mirror.

ESO 415-19, a spiral galaxy. It has a bright core with patches of dark dust, and fuzzier, dimmer spiral arms in cooler colours, with spots of bright blue. Long, faint tidal streams stretch from the galaxy’s arms: one up to the top of the frame, one curving down to the bottom-left corner. In the top-right there is a smaller, orange elliptical galaxy. The background is studded with many tiny stars and galaxies.

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Image Credit: ESA/Hubble & NASA, J. Dalcanton,
Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA

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The peculiar spiral galaxy ESO 415-19, which lies around 450 million light-years away, stretches lazily across this image from the NASA/ESA Hubble Space Telescope. While the centre of this object resembles a regular spiral galaxy, long streams of stars stretch out from the galactic core like bizarrely elongated spiral arms. These are tidal streams caused by some chance interaction in the galaxy’s past, and give ESO 415-19 a distinctly peculiar appearance.

ESO 415-19’s peculiarity made it a great target for Hubble. This observation comes from an ongoing campaign to explore the Arp Atlas of Peculiar Galaxies, a menagerie of some of the weirdest and most wonderful galaxies that the Universe has to offer. These galaxies range from bizarre lonesome galaxies to spectacularly interacting galaxy pairs, triplets, and even quintets. These space oddities are spread throughout the night sky, which means that Hubble can spare a moment to observe them as it moves between other observational targets.

This particular observation lies in a part of the night sky contained by the Fornax constellation. This constellation was also the site of a particularly important Hubble observation; the Hubble Ultra Deep Field. Creating the Ultra Deep Field required almost a million seconds of Hubble time, and captured nearly 10,000 galaxies of various ages, sizes, shapes, and colours. Just as climate scientists can recreate the planet’s atmospheric history from ice cores, astronomers can use deep field observations to explore slices of the Universe’s history from the present all the way to when the Universe was only 800 million years old!

Image Credit: ALMA (ESO/NAOJ/NRAO)/MJ Maureira et al

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This Picture of the Week shows the very early stages of a binary star system with some intriguing features. It’s a radio image taken with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, of which ESO is a partner. The two young stars, or protostars –– marked with star symbols –– are surrounded by a dusty disc. The colour represents the temperature distribution of the protostars and the surrounding area, with brighter yellow colours representing higher temperatures. There are three clumps of hot dust far away from the protostars, marked with crosses, but what’s heating them? 

A recent study, led by Maria Jose Maureira at the Max Planck Institute for Extraterrestial Physics in Germany, suggests that these regions are not only heated by the protostars but, most likely, also by shockwaves, similar to the ones produced when an airplane travels faster than the sound speed through air. These shocks can help enrich the gas in the disc with complex organic molecules at early stages, which could be passed on to nascent planets. The high temperatures in these shocks can also alter how dust particles stick together, changing how early the formation of planetary cores can occur.

• Astrophysical Journal Letters 941(2):L23 (2022 Dec 20) DOI: 10.3847/2041-8213/aca53a
• arXiv | astro-ph | arXiv:2212.08436 | 16 Dec 2022