The studies suggested that the galaxy had erupted with star formation billions of years after its galactic neighbours, like our galaxy the Milky Way. Back then it was an important finding for astronomers, since this young galaxy was also nearby and could be studied in great detail; something that is not possible with observations made across great distances when the universe was much younger.
Hubble Finds Mature Galaxy Masquerading as Toddler Click for larger image The NASA/ESA Hubble Space Telescope quashed the possibility that what was previously believed to be a toddler galaxy in the nearby universe may actually be considered an adult. Called I Zwicky 18, this galaxy has a youthful appearance that resembles galaxies typically found only in the early universe. Hubble has now found faint, older stars within this galaxy, suggesting that the galaxy may have formed at the same time as most other galaxies. I Zwicky 18 is classified as a dwarf irregular galaxy and is much smaller than our Milky Way Galaxy. The concentrated bluish-white knots embedded in the heart of the galaxy are two major starburst regions where stars are forming at a furious rate. The wispy blue filaments surrounding the central starburst regions are bubbles of gas that have been blown away by stellar winds and supernovae explosions from a previous generation of hot, young stars. This gas is now heated by intense ultraviolet radiation unleashed by hot, young stars. A companion galaxy lies just above and to the left of I Zwicky 18. The companion may be interacting with I Zwicky 18 by gravitationally tugging on the galaxy. The interaction may have triggered the galaxy’s recent star formation that is responsible for the youthful appearance. Besides the bluish-white young stars, white-reddish stars also are visible in both I Zwicky 18 and its companion. These stars may be as old as 10 billion years. The reddish extended objects surrounding I Zwicky 18 and its companion are ancient, fully formed galaxies of different shapes that are much farther away. Hubble data also allowed astronomers for the first time to identify Cepheid variable stars in I Zwicky 18. These flashing stellar mile-markers were used to determine that I Zwicky 18 is 59 million light-years from Earth, almost 10 million light-years more distant than previously believed. The observations of I Zwicky 18 were taken in 2005 and 2006 with Hubble’s Advanced Camera for Surveys. Astronomers made this image by combining observations taken with blue and red filters. The science team consists of Alessandra Aloisi and Marco Sirianni of the European Space Agency and Space Telescope Science Institute; Francesca Annibali,Jennifer Mack, and Roeland van der Marel of the Space Telescope Science Institute; Abhijit Saha of the National Optical Astronomy Observatories; and Gisella Clementini, Rodrigo Contreras, Giuliana Fiorentino, Marcella Marconi, Ilaria Musella, and Monica Tosi of the Italian National Astrophysics Institutes in Bologna and Naples.
But these new Hubble data have quashed that possibility. The telescope found fainter older red stars contained within the galaxy, suggesting its star formation started at least one billion years ago and possibly as much as 10 billion years ago. The galaxy, therefore, may have formed at the same time as most other galaxies.
“Although the galaxy is not as youthful as was once believed, it is certainly developmentally challenged and unique in the nearby Universe,” said astronomer Alessandra Aloisi from the European Space Agency/Space Telescope Science Institute, who led the new study. Spectroscopic observations with ground-based telescopes have shown that I Zwicky 18 is mostly composed of hydrogen and helium, the main ingredients created in the Big Bang. In other words the stars within it have not created the same amounts of heavier elements as seen in other galaxies nearby. Thus the galaxy’s primordial makeup suggests that its rate of star formation has been much lower than that of other galaxies of similar age. The galaxy has been studied with most of NASA’s telescopes, including the Spitzer Space Telescope, the Chandra X-ray Observatory, and the Far Ultraviolet Spectroscopic Explorer (FUSE). However, it remains an outstanding mystery why I Zwicky 18 formed so few stars in the past, and why it is forming so many new stars right now.
The new Hubble data also suggest that I Zwicky 18 is 59 million light-years from Earth, almost 10 million light-years more distant than previously believed. On extragalactic standards this is still in our own backyard yet the galaxy’s larger-than-expected distance may now explain why astronomers have had difficulty detecting older, fainter stars within the galaxy until now. In fact, the faint old stars in I Zwicky 18 are almost at the limit of Hubble’s sensitivity and resolution.
Aloisi and her team discerned the new distance by observing blinking stellar distance-markers within I Zwicky 18. These massive stars, called Cepheid variables, pulse with a regular rhythm. The timing of their pulsations is directly related to their brightness. By comparing their actual brightness with their observed brightness, astronomers can precisely measure their distance. The team determined the observed brightness of three Cepheids and compared it to the actual brightness predicted by theoretical models specifically calculated for the low metal content of I Zwicky 18 in order to determine the galaxy’s distance. The Cepheid distance was also validated through another distance indicator, specifically the observed brightness of the brightest red stars in a characteristic stellar evolutionary phase (the so-called “giant” phase).
Cepheid variable stars have been studied for decades (especially by Hubble) and have been instrumental in the determination of the scale of our universe. This is the first time, however, that variable stars with so few heavy elements were found. This may provide unique new insights into the properties of variable stars, which is now a topic of ongoing study.
Lars Christensen | alfa
Astronomers release most complete ultraviolet-light survey of nearby galaxies
18.05.2018 | NASA/Goddard Space Flight Center
A quantum entanglement between two physically separated ultra-cold atomic clouds
17.05.2018 | University of the Basque Country
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology