Wandering Stars Have Been Adrift Between Galaxies for Billions of Years

Hubble Space Telescope images of two massive clusters of galaxies named MOO J1014+0038 (left panel) and SPT-CL J2106-5844 (right panel).. Credits: NASA/ESA/STScI/James Jee (Yonsei University)/Joseph DePasquale (STScI)

In the giant galaxy clusters in the Universe, which can consist of hundreds or thousands of galaxies, there are countless “rogue” stars wandering between them. These stars are not gravitationally bound to any individual galaxy but to the halo of galaxy clusters themselves and are only discernible by the diffuse light they emit – “Ghost Light” or “Intracluster light” (ICL). For astronomers, the explanation for how these stars became so scattered throughout their galaxy clusters has always been an unresolved question.

There are several theories, including the possibility that the stars were pulled from their galaxies, ejected in the course of galactic mergers, or were part of their cluster since its early formation billions of years ago. Using NASA’s Hubble Space Telescope, a team from Yonsei University, Seoul, and the University of California, Davis, conducted an infrared survey of distant galaxy clusters. Their observations suggest that these wandering stars have been adrift for billions of years and were not stripped from their respective galaxies.

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Hubble and Spitzer Team up to Find a Pair of Waterworld Exoplanets

Artist’s impression of a water world, where half of its mass consists of water. Just like our Moon, the planet is bound to its star by tidal forces and always shows the same face to its host star. Credit: Pilar Montañés

As of December 19th, 2022, 5,227 extrasolar planets have been confirmed in 3,908 systems, with over 9,000 more awaiting confirmation. While most of these planets are Jupiter- or Neptune-sized gas giants or rocky planets many times the size of Earth (Super-Earths), a statistically significant number have been planets where water makes up a significant part of their mass fraction – aka. “water worlds.” These planets are unlike anything we’ve seen in the Solar System and raise several questions about planet formation in our galaxy.

In a recent study, an international team led by researchers from the University of Montreal’s Institute for Research on Exoplanets (iREx) found evidence of two water worlds in a single planetary system located about 218 light-years away in the constellation Lyra. Based on their densities, the team determined that these exoplanets (Kepler-138c and Kepler-138d) are lighter than rocky “Earth-like” ones but heavier than gas-dominated ones. The discovery was made using data from NASA’s now-retired Spitzer Space Telescope and the venerable Hubble Space Telescope.

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Here's a new Image of the Carina Nebula From Hubble

The Carina Nebula is an enormous stellar nursery about 7,500 light-years from Earth in the southern constellation Carina, the Keel. Credits: NASA, ESA, A. Kraus (University of Texas at Austin), and ESO; Processing: Gladys Kober (NASA/Catholic University of America)

Like a famous (and photogenic) actor followed by paparazzi, the Carina Nebula is one of the most photographed objects in space because of its stunning beauty. Over the years, the Carina Nebula has been one of the Hubble Space Telescope’s most-imaged objects.

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Hubble Sees a Glittering Jewel in the Small Magellanic Cloud. But the Jewel is Disappearing

A small portion of the Small Magellanic Cloud (SMC) is pictured in this image from the NASA/ESA Hubble Space Telescope. Image Credit: NASA/ESA

As far as we know, nobody lives in our neighbour, the Small Magellanic Cloud (SMC.) So it’s okay to point our telescope there and gaze at it.

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A new Hubble Image Reveals a Shredded Star in a Nearby Galaxy

The latest composite image of supernova remnant DEM L 190, released in November 2022. Credit: ESA/Hubble & NASA, S. Kulkarni, Y. Chu

The Hubble Space Telescope, to which we owe our current estimates for the age of the universe and the first detection of organic matter on an exoplanet, is very much doing science and still alive. It’s latest masterpiece remixes an old hit – apparently a growing trend in space science as well as space music.

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Hubble Spots Two Open Clusters. One is Also an Emission Nebula

The open cluster NGC 1858, seen in this Hubble image, contains stars of different ages. Image Credit: NASA, ESA and G. Gilmore (University of Cambridge); Processing: Gladys Kober (NASA/Catholic University of America)

Open star clusters are groups of stars in loosely-bound gravitational associations. The stars are further apart than the stars in their cousins, the globular clusters. The weak gravity from the loose clusters means open clusters take on irregular shapes. They usually contain only a few thousand stars.

The Hubble Space Telescope captured images of two clusters in the Large Magellanic Cloud.

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By Looking Back Through Hubble Data, Astronomers Have Identified six Massive Stars Before They Exploded as Core-Collapse Supernovae

Hubble Space Telescope
NASA's Hubble Space Telescope flies with Earth in the background after a 2002 servicing mission. Credit: NASA.

The venerable Hubble Space Telescope has given us so much during the history of its service (32 years, 7 months, 6 days, and counting!) Even after all these years, the versatile and sophisticated observatory is still pulling its weight alongside more recent addition, like the James Webb Space Telescope (JWST) and other members of NASA’s Great Observatories family. In addition to how it is still conducting observation campaigns, astronomers and astrophysicists are combing through the volumes of data Hubble accumulated over the years to find even more hidden gems.

A team led by Caltech’s recently made some very interesting finds in the Hubble archives, where they observed the sites of six supernovae to learn more about their progenitor stars. Their observations were part of the Hubble Space Telescope Snapshot program, where astronomers use HST images to chart the life cycle and evolution of stars, galaxies, and other celestial objects. From this, they were able to place constraints on the size, mass, and other key characteristics of the progenitor stars and what they experienced before experiencing core collapse.

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Two Great Globular Clusters Seen by Hubble: Pismis 26 and Ruprecht 106

Pismis 26, a globular star cluster located about 23,000 light-years away, as seen by the Hubble Space Telescope. Credit: NASA, ESA and R. Cohen (Rutgers the State University of New Jersey); Processing: Gladys Kober (NASA/Catholic University of America).

If you like shiny things, some of the most gorgeous objects in space are globular clusters, with their bright, densely packed collections of gleaming stars. And if you like globular clusters, you’re in luck: two different Hubble images of globular clusters were featured this week by NASA and ESA.

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Gaze Slack-jawed at the Haunting Beauty of Galaxy NGC 1566, Captured by JWST, Processed by Judy Schmidt

NGC 1566, as seen by the James Webb Space Telescope's Mid-Infrared Instrument. Credit: NASA/ESA/CSA/Judy Schmidt.

Here’s an absolutely stunning new view from the James Webb Space Telescope of a dusty spiral galaxy, NGC 1566. Amateur (but expert!) image editor Judy Schmidt took the raw data from JWST’s Mid-Infrared Instrument (MIRI) and teased out this eerie, spider-web-like view of this distant galaxy. The swirling and symmetrical arms are so full of dust that not many stars are visible.

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Hubble saw the Same Supernova at Three Different Times Thanks to Gravitational Lensing

supernova explosion
The Crab Nebula; at its core is a long dead star. Did early massive stars die in supernova explosions like this? Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)

As cosmic events go, supernova explosions epitomize the saying, “Live fast, die young, and leave a good-looking corpse.” They’re the deaths of stars so massive that they tear through their fuel in a short time. Then, they explode and create gorgeous scenes of stellar destruction. These seminal events enrich the universe with chemical elements for new generations of stars and planets.

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