Space

Gaia Has Created the Richest Star Map of Our Galaxy and Beyond

Gaia Has Created The Richest Star Map of Our Galaxy and Beyond. (Image: Screenshot via YouTube)


A multitude of discoveries are on the horizon after a much-awaited release that is based on 22 months of charting the sky as part of Gaia’s mission to produce the largest, most precise three-dimensional map of our Galaxy ever created.

The new data includes positions, distance indicators, and motions of more than 1 billion stars, along with high-precision measurements of asteroids within our Solar System and stars beyond our own Milky Way Galaxy.

Preliminary analysis of this phenomenal data reveals fine details about the makeup of the Milky Way’s stellar population and about how stars move, essential information for investigating the formation and evolution of our home Galaxy, Günther Hasinger, ESA Director of Science said:

This unique mission is reliant on the work of Cambridge researchers who collect the vast quantities of data transmitted by Gaia to a data processing centre at the University, overseen by a team at the Institute of Astronomy.

Cambridge’s Professor Gerry Gilmore, Principal Investigator for the UK participation in the Gaia Data Processing and Analysis Consortium, and one of the original proposers of the mission to ESA, said:

Gaia was launched in December 2013 and started science operations the following year. The first data release, based on just over one year of observations, was published in 2016; it contained distances and motions of 2 million stars.

The new data release, which covers the period between July 25, 2014 and May 23, 2016, pins down the positions of nearly 1.7 billion stars, and with a much greater precision.

For some of the brightest stars in the survey, the level of precision equates to Earth-bound observers being able to spot a Euro coin lying on the surface of the Moon.

With these accurate measurements, it is possible to separate the parallax of stars — an apparent shift on the sky caused by Earth’s yearly orbit around the Sun — from their true movements through the Galaxy.

The new catalogue lists the parallax and velocity across the sky, or proper motion, for more than 1.3 billion stars. From the most accurate parallax measurements, about 10 percent of the total, astronomers can directly estimate distances to individual stars.

The comprehensive dataset provides a wide range of topics for the astronomy community. As well as positions, the data include brightness information of all surveyed stars and color measurements of nearly all, plus information on how the brightness and color of half a million variable stars change over time.

It also contains the velocities along the line of sight of a subset of 7 million stars, the surface temperatures of about a hundred million and the effect of interstellar dust on 87 million.

Gaia also observers objects

Gaia also observes objects in our Solar System: The second data release comprises the positions of more than 14,000 known asteroids, which allows precise determination of their orbits. A much larger asteroid sample will be compiled in Gaia’s future releases.

Further afield, Gaia closed in on the positions of half a million distant quasars, bright galaxies powered by the activity of the supermassive black holes at their cores.

These sources are used to define a reference frame for the celestial coordinates of all objects in the Gaia catalogue, something that is routinely done in radio waves, but now for the first time is also available at optical wavelengths.

Major discoveries are expected to come once scientists start exploring Gaia’s new release. An initial examination performed by the data consortium to validate the quality of the catalog has already unveiled some promising surprises — including new insights on the evolution of stars.

The team in Cambridge is led by Dr. Floor van Leeuwen, Dr. Dafydd Wyn Evans, Dr. Francesca De Angeli, and Dr. Nicholas Walton. De Angeli, head of the Cambridge processing center said:

Evans explained:

Van Leeuwen, Project Manager for the UK and European photometric processing work, added:

Walton, a member of the ESA Gaia Science Team, said:

More data releases will be issued in future years, with the final Gaia catalog to be published in the 2020s. This will be the definitive stellar catalog for the foreseeable future, playing a central role in a wide range of fields in astronomy, Gilmore added:

Provided by: University of Cambridge [Note: Materials may be edited for content and length.]

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Dark Matter May Not Be Interactive After All

Hubble Space Telescope image of the four giant galaxies at the heart of cluster Abell 3827. An almost three-hour exposure shows the view at wavelengths visible to the human eye and the near infrared, as used in the original 2015 study. The distorted image of a more distant galaxy behind the cluster is faintly visible, wrapped around the four galaxies. (Image: Richard Massey (Durham University) via NASA / ESA}

Space Radiation Is Becoming Increasingly More Hazardous

Space radiation is becoming increasingly more hazardous.

It might sound like something from a science fiction plot — astronauts traveling into deep space being bombarded by cosmic rays — but space radiation exposure is science fact.

As future missions look to travel back to the moon or even to Mars, new research from the University of New Hampshire’s Space Science Center cautions that the exposure to radiation is much higher than previously thought and could have serious implications on both astronauts and satellite technology.

Space radiation becoming worse and more hazardous

In their study, recently published in the journal Space Weather, the researchers found that large fluxes in Galactic Cosmic Rays (GCR) are rising faster and are on path to exceed any other recorded time in the space age.

They also point out that one of the most significant Solar Energetic Particle (SEP) events happened in September 2017, releasing large doses of radiation that could pose significant risk to both humans and satellites.

Unshielded astronauts could experience acute effects like radiation sickness or more serious long-term health issues like cancer and organ damage, including to the heart, brain, and central nervous system.

In 2014, Schwadron and his team predicted around a 20 percent increase in space radiation dose rates from one solar minimum to the next. Four years later, their newest research shows current conditions exceed their predictions by about 10 percent, showing the radiation environment is worsening even more than expected.

The authors used data from CRaTER on NASA’s Lunar Reconnaissance Orbiter (LRO). Lunar observations (and other space-based observations) show that GCR space radiation doses are rising faster than previously thought.

Researchers point to the abnormally long period of the recent quieting of solar activity. In contrast, an active sun has frequent sunspots, which can intensify the sun’s magnetic field.

That magnetic field is then dragged out through the solar system by the solar wind and deflects galactic cosmic rays away from the solar system — and from any astronauts in transit.

For most of the space age, the sun’s activity ebbed and flowed like clockwork in 11-year cycles, with 6- to 8-year lulls in activity, called solar minimum, followed by 2- to 3-year periods when the sun is more active.

However, starting around 2006, scientists observed the longest solar minimum and weakest solar activity observed during the space age.

Despite this overall reduction, the September 2017 solar eruptions produced episodes of significant Solar Particle Events and associated space radiation caused by particle acceleration by successive, magnetically well-connected coronal mass ejections.

The researchers conclude that the radiation environment continues to pose significant hazards associated both with historically large galactic cosmic ray fluxes and large but isolated SEP events, which still challenge space weather prediction capabilities.

Provided by: University of New Hampshire [Note: Materials may be edited for content and length.]

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