Category: vialactea

Milky Way’s Biggest Globular Cluster Unlikel…

Milky Way’s Biggest Globular Cluster Unlikely to Host Habitable Exoplanets

Close encounters between stars in Omega Centauri, the only star cluster visible to the naked eye, leave little room for habitable planets, according to new research.

In the hunt for habitable exoplanets, Omega Centauri, the largest globular cluster in the Milky Way, seemed like a good place to look. Comprising an estimated 10 million stars, the cluster is nearly 16,000 light years from Earth, making it visible to the naked eye and a relatively close target for observations by the Hubble Space Telescope.

Starting with a rainbow-colored assortment of 470,000 stars in Omega Centauri’s core, the researchers homed in on 350,000 stars whose color—a gauge of their temperature and age—means they could potentially harbor life-bearing planets.

For each star, they then calculated the habitable zone—the orbital region around each star in which a rocky planet could have liquid water, which is a key ingredient for life as we know it. Since most of the stars in Omega Centauri’s core are red dwarfs, their habitable zones are much closer than the one surrounding our own larger sun.

“The core of Omega Centauri could potentially be populated with a plethora of compact planetary systems that harbor habitable-zone planets close to a host star,” Kane said. “An example of such a system is TRAPPIST-1, a miniature version of our own solar system that is 40 light years away and is currently viewed as one of the most promising places to look for alien life.”

Ultimately, though, the cozy nature of stars in Omega Centauri forced the researchers to conclude that such planetary systems, however compact, cannot exist in the cluster’s core. While our own sun is a comfortable 4.22 light years from its nearest neighbor, the average distance between stars in Omega Centauri’s core is 0.16 light years, meaning they would encounter neighboring stars about once every 1 million years.

“The rate at which stars gravitationally interact with each other would be too high to harbor stable habitable planets,” Deveny said. “Looking at clusters with similar or higher encounter rates to Omega Centauri’s could lead to the same conclusion. So, studying globular clusters with lower encounter rates might lead to a higher probability of finding stable habitable planets.” source

Milky Way by Niilo Isotalo

Milky Way

by Niilo Isotalo

The Magellanic Clouds are two irregular dwarf …

The Magellanic Clouds are two irregular dwarf galaxies visible in the Southern Celestial Hemisphere; they are members of the Local Group and are orbiting the Milky Way galaxy. Because they both show signs of a bar structure, they are often reclassified as Magellanic spiral galaxies. The two galaxies are:

  • Large Magellanic Cloud (LMC), approximately 160,000 light-years away.
  • Small Magellanic Cloud (SMC), approximately 200,000 light years away.

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Image credit: Primoz Cigler, Joseph Brimacombe,

Ed Dunens and EkantTakePhotos

Stars orbiting the Supermassive Black Hole a…

Stars orbiting the Supermassive Black Hole at our Galactic Center.

This demo shows the observed and predicted orbits of thirteen stars that were used by astronomers at the Keck/UCLA Galactic Center Group to predict the position of a huge black hole at the center of the Milky Way. This data was provided by Andrea Ghez and Jessica Lu.

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Milky Way On the shore of Lake Dumbleyung …

Milky Way

On the shore of Lake Dumbleyung

by

William Vrbasso

This vibrant image from NASA’s Spitzer…

This vibrant image from NASA’s Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy.

Image credit: NASA/JPL-Caltech/STScI

On this day in 1889 was born the astronomer Ed…

On this day in 1889 was born the astronomer Edwin Hubble!

Edwin Hubble played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology and is regarded as one of the most important astronomers of all time.

Hubble discovered that many objects previously thought to be clouds of dust and gas and classified as “nebulae” were actually galaxies beyond the Milky Way. He used the strong direct relationship between a classical Cepheid variable’s luminosity and pulsation period (discovered in 1908 by Henrietta Swan Leavitt) for scaling galactic and extragalactic distances.

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Hubble provided evidence that the recessional velocity of a galaxy increases with its distance from the earth, a property known as “Hubble’s law”, a preliminary version of which was proposed earlier by Georges Lemaître. Hubble’s Law implies that the universe is expanding. A decade before, the American astronomer Vesto Slipher had provided the first evidence that the light from many of these nebulae was strongly red-shifted, indicative of high recession velocities.

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Hubble’s name is most widely recognized for the Hubble Space Telescope which was named in his honor, with a model prominently displayed in his hometown of Marshfield, Missouri.

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Hubble also devised the most commonly used system for classifying galaxies, grouping them according to their appearance in photographic images. He arranged the different groups of galaxies in what became known as the Hubble sequence .

  • Sa (SBa) – tightly wound, smooth arms; large, bright central bulge
  • Sb (SBb) – less tightly wound spiral arms than Sa (SBa); somewhat fainter bulge
  • Sc (SBc) – loosely wound spiral arms, clearly resolved into individual stellar clusters and nebulae; smaller, fainter bulge.
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In 1929 he demonstrated that the galaxies move away at great speed and that this speed increases with the distance. The relationship between velocity and distance from Earth is known as the Hubble Law and the ratio between the two values is known as Hubble’s Constant. If a galaxy is approaching, the light shifts to the blue color and if it is moving away from the light to the red color (Doppler effect). In each case, the relative variation of length is proportional to the speed at which the source moves.

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Hubble’s law

Hubble’s law is the name for the observation in physical cosmology that:

  1. Objects observed in deep space (extragalactic space, 10 megaparsecs (Mpc) or more) are found to have a red shift, interpreted as a relative velocity away from Earth;
  2. This Doppler shift-measured velocity, of various galaxies receding from the Earth, is approximately proportional to their distance from the Earth for galaxies up to a few hundred megaparsecs away.

When you hear the name “Hubble”, you probably think of the NASA/ESA Hubble Space Telescope. But, decades before the Hubble Space Telescope, Dr Edwin Powell Hubble revolutionised the field of astronomy. In the newest Hubblecast, we take a look at the life and work of this brilliant American astronomer for whom the Hubble Space Telescope is named.

  • Source: wikipedia [1, 2, 3, 4]
  • Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
  • Video: www.spacetelescope.org

Is there proof of that the centre of our galaxy is a blackhole?

Probably yes, astronomers believe that practically every galaxy has a black hole in its center, in…

The Andromeda Galaxy Is Coming To Get Us!Credit: Science…

The Andromeda Galaxy Is Coming To Get Us!

Credit:

Science Channel | Watch the video here 

Astronomy and Astrophysics: Facts

Here is a list of some curiosities of astronomy and astrophysics. From our solar system to…