Pic of the Week: Hickson Compact Group 40

Posted on by onespaceman2000
Image (Credit): The NASA/ESA Hubble Space Telescope view of five galaxies, called the Hickson Compact Group 40. (NASA/ESA Hubble)

This week’s image is from the NASA/ESA Hubble Space Telescope. It shows an amazing collection of five galaxies in close proximity to one another in what is known as the Hickson Compact Group 40. In about one billion years they are expected to coalesce into one large galaxy.

Here is the summary from the Hubble site:

This menagerie includes three spiral-shaped galaxies, an elliptical galaxy and a lenticular (lens-like) galaxy. Somehow, these different galaxies have crossed paths to create an exceptionally crowded and eclectic galaxy sampler.

Caught in a leisurely gravitational dance, the whole group is so crowded that it could fit within a region of space that is less than twice the diameter of our Milky Way’s stellar disc.

Though such galaxy groupings can be found in the heart of huge galaxy clusters, these galaxies are notably isolated in their own small patch of the Universe, in the direction of the constellation Hydra.

One possibility is that there’s a lot of dark matter (a poorly understood and invisible form of matter) associated with these galaxies. If they come close together the dark matter can form a big cloud within which the galaxies orbit. As the galaxies plough through the dark matter they feel a frictional force that results from its gravitational effects. This slows their motion and makes the galaxies lose energy, so they fall together. Therefore, this snapshot catches the galaxies at a very special moment in their lifetimes. In about 1 billion years they will eventually collide and merge to form a single giant elliptical galaxy.

Astronomers have studied this compact galaxy group not only in visible light, but in radio, infrared, and at X-ray wavelengths. Almost every one of the galaxies has a compact radio source at its core, which could be evidence for the presence of a supermassive black hole. X-ray observations show that the galaxies have been gravitationally interacting as witnessed by the presence of a lot of hot gas amongst them. Infrared observations reveal clues to the rate of formation of new stars.

Though over 100 such compact galaxy groups have been catalogued in sky surveys going back several decades, Hickson Compact Group 40 is one of the most densely packed. Observations suggest that such tight groups may have been more abundant in the early Universe and provided fuel for powering black holes, known as quasars, whose light from superheated inflating material blazed across space. Studying the details of galaxies in nearby groups like this helps astronomers sort out when and where galaxies assembled themselves, and what they are assembled from.

Space Stories: JWST, a Galaxy Catalog, and a Stellar Graveyard

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Image (Credit): JWST image of the Tarantula Nebula, which is about 160,000 light-years away. (NASA, ESA, CSA, STScI)

Here are some recent stories of interest.

—Nature.com: “‘Bit of Panic’: Astronomers Forced to Rethink Early Webb Telescope Findings“

Astronomers have been so keen to use the new James Webb Space Telescope (JWST) that some have got a little ahead of themselves. Many started analysing Webb data right after the first batch was released, on 14 July, and quickly posted their results on preprint servers — but are now having to revise them. The telescope’s detectors had not been calibrated thoroughly when the first data were made available, and that fact slipped past some astronomers in their excitement.

—DailyScience.com: “‘Astronomers Map Distances to 56,000 Galaxies, Largest-ever Catalog“

How old is our universe, and what is its size? A team of researchers led by University of Hawaii at Manoa astronomers Brent Tully and Ehsan Kourkchi from the Institute for Astronomy have assembled the largest-ever compilation of high-precision galaxy distances, called Cosmicflows-4. Using eight different methods, they measured the distances to a whopping 56,000 galaxies. The study has been published in the Astrophysical Journal.

—University of Sydney: “Milky Way’s Graveyard of Dead Stars Found“

The first map of the ‘galactic underworld’ – a chart of the corpses of once massive suns that have since collapsed into black holes and neutron stars – has revealed a graveyard that stretches three times the height of the Milky Way, and that almost a third of the objects have been flung out from the galaxy altogether.

Astronomy Ideas on Borrowed Time?

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Image (Credit): The position of our Sun as it orbits the Milky Way’s center. (Stefan Payne-Wardenaar)

A recent Big Think story, “5 Consensus Ideas in Astronomy That Might Soon be Overturned,” comes as a good time as we reach further into space and back into time using the James Webb Space Telescope (JWST) and contemplate other telescopes that should come online shortly.

The story highlights these five ideas:

  • Dark energy is a cosmological constant;
  • Stars predate black holes;
  • Jovian planets protect terrestrial ones;
  • Most of the galaxy is uninhabitable; and
  • Globular clusters are planet-free.

For instance, regarding the uninhabitable areas of the galaxy, the Big Think story states:

Among its many discoveries, the ESA’s Gaia mission has found that the Milky Way galaxy not only has a warp to its galactic disk, but that the warp in the disk precesses and wobbles, completing a full rotation for roughly every three revolutions of the Sun [shown in yellow above] around the galactic center. Most astronomers assume that regions with too many stellar cataclysms in them, like the centers of galaxies, may be completely uninhabitable. But this picture is far from certain.

It is worth reading through the list and keeping these ideas in mind, and then following the JWST stories as they unfold. I bet you will be able to make a much longer list as old consensus ideas come apart and new ideas quickly follow.

More on Black Holes

Posted on by onespaceman2000
Image (Credit): Image from the Very Large Telescope in Chile showing stars orbiting the supermassive black hole that lies at the heart of the Milky Way. (ESO/MPE)

The earlier article on a black hole binary system was pretty amazing, yet the video accompanying the story was created to demonstrate the phenomena. I found an even more amazing real video of stars orbiting the supermassive black hole at the center or the Milky Way galaxy. You can see the 20-year time-lapse video here from the NaCo instrument on the European Space Telescope’s Very Large Telescope in Chile. This black hole, Sagittarius A*, is about 27 000 light-years away from Earth.

Space Stories: Black Holes, X-Rays, and Exploding Stars

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Image (Credit): Animation showing a binary system of a large, hot blue star and a black hole orbiting each other. (ESO/L.Calçada)

Here are some recent stories of interest.

—SciTechDaily.com: “Astronomers Have Discovered an Especially Sneaky Black Hole“

VFTS 243 is a binary system, which means it is composed of two objects that orbit a common center of mass. The first object is a very hot, blue star with 25 times the mass of the Sun, and the second is a black hole nine times more massive than the Sun. VFTS 243 is located in the Tarantula Nebula within the Large Magellanic Cloud, a satellite galaxy of the Milky Way located about 163,000 light-years from Earth.

—SpaceNews.com: “ESA Scaling Back Design of X-ray Astronomy Mission“

Faced within increasing costs, the European Space Agency is looking for ways to revise the design of a large X-ray space telescope, an effort that could have implications for NASA’s own astrophysics programs…That effort will involve potential changes to its instrument configuration as well as creation of a science “redefinition” team to reconsider science objectives. The goal will be to develop a revised concept, called a minimum disrupted mission, that will cost ESA no more than 1.3 billion euros but still perform science expected of a flagship-class mission.

—NASA.gov: “NASA Rocket Mission Using ‘Astronomical Forensics’ to Study Exploded Star“

A NASA-funded sounding rocket mission will observe the remnants of an exploded star, uncovering new details about the eruption event while testing X-ray detector technologies for future missions. The High-Resolution Microcalorimeter X-ray Imaging, or Micro-X, experiment will launch Aug. 21 from the White Sands Missile Range in New Mexico. The mission’s target of study is some 11,000 light-years away from Earth, off the edge of the W-shaped constellation known as Cassiopeia. There, a massive bubble of radiant material known as Cassiopeia A, or Cas A for short, marks the site of a brilliant stellar death.