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Gaia begins to depict the galactic ledge in the Milky Way



  Gaia Begins Mapping the Galactic Beam in the Milky Way
This color chart, overlaid on an artistic representation of the galaxy, shows the distribution of 150 million stars in the Milky Way, based on data from the second publication of Gaia The ESA investigated missions in combination with infrared and optical surveys, with orange / yellow hues indicating a greater density of stars. Most of these stars are red giants. While the majority of mapped stars are closer to the sun (the larger orange / yellow spot in the lower part of the image), a large and elongated feature populated by many stars is also in the visible central region of the galaxy: this is the first geometric statement of the galactic bar. The distances to the stars shown in this table, as well as their surface temperature and extinction – a measure of how much dust there is between us and the stars – were estimated using the StarHorse computer code. Credit: Data: ESA / Gaia / DPAC, A. Khalatyan (AIP) & StarHorse Team; Galaxy Map: NASA / JPL-Caltech / R. Injured (SSC / Caltech)

The second release of data from the Gaia satellite to star mapping, published in 2018, has revolutionized many areas of astronomy. The unprecedented catalog contains information on brightness, positions, distance indicators, and sky movements for more than a billion stars in our Milky Way, as well as information about other celestial bodies.

This is only the beginning. While the second release is based on Gaasa's surveys for the first twenty-two months, the satellite has been scanning the sky for five years and will do so until at least 2022. New data releases planned in the coming years will steadily improve the measurements as follows In the meantime, a team of astronomers combined the latest Gaia data with infrared and optical observations made from ground and space "We have In particular, we consider two of the star parameters contained in the Gaia data: the surface temperature of stars and the "extinction", which is basically a measure of the temperature. How much dust is between us and the stars, whose light is darkened and redder leaves, "says Friedrich Anders, ICCUB member and lead author of the new study.

"These two parameters The data is interconnected, but we can independently estimate it by adding additional information obtained by scanning the dust with infrared observations," continues the expert, developed by co-author Anna Queiroz and other employees. The code compares the observations with star models to determine the surface temperature of stars, the extinction and an improved estimate of the distance to the stars.

Astronomers were able to better determine the distance to about 150 million stars – in some cases, the improvement is up to 20% or more. This allowed them to track the distribution of stars across the Milky Way to much greater distances than was possible with the original Gaia data alone.




3D visualization of the star density in the ESA / Gaia data version 2. The view revolves around the solar position. The color encodes the density: blue is low, yellow / orange are high. Due to the Gaia selection function, the highest star density is measured near the Sun, but it is also possible to detect some nearby star clusters and even the galactic bars (mainly its orange star clusters). Credit: StarHorse Team. Visualization: Arman Khalatyan; Credit Background image at the top of the video: NASA / Caltech / R. Hurt

"With the second release of the Gaia data, we were able to sample a radius around the Sun of about 6500 light years, but with our new catalog we can & # 39; Gaia – sphere – expand three or four times and extend to the earth center of the Milky Way, "explains co-author Cristina Chiappini of the Leibniz Institute for Astrophysics Potsdam, where the project was coordinated. In the center of our galaxy, the data clearly shows a large, elongated feature in the three-dimensional distribution of stars: the galactic bar.

"We know that the Milky Way has a beam, like other spiral galaxies with lattices, but so far we only had indirect clues to the motion of stars and gas, or to the number of stars in infrared measurements, this is the first time that we see the galactic beam in three-dimensional space, based on geometric measurements of the star distances, "says Friedrich Anders.

"Ultimately, we are interested in galactic archeology: we want to reconstruct how the milk is shaped and evo To achieve this, we need to understand the history of each component," adds Cristina Chiappini.

"It is still unclear how the rod – a large amount of stars and gas, which spin rigidly around the center of the galaxy – formed, but with Gaia and other upcoming polls over the next few years, we're certainly on the right track to it find out, "notes the researcher.

The team is looking forward to the next data release from the Apache Point Observatory Galaxy Evolution Experiment (APOGEE-2) as well as upcoming facilities such as the 4m telescope for surveying multiple objects (4MOST) at the European Southern Observatory in Chile and surveying WEAVE (WHT Enhanced Area Velocity Explorer) at the William Herschel Telescope (WHT) on La Palma (Canary Islands).

The third release of the Gaia data, which is currently scheduled for 2021, will involve significantly improved range finding for a much larger number of stars and is expected to allow advances in our world to understand the complex area at the center of the Milky Way.

"With this study, we can get a taste of the improvements in our knowledge of the Milky Way that can be expected from Gaia measurements in the third data release," said co-author Anthony Brown of Leiden University (The Netherlands).

"We reveal features in the Milky Way that we could not see otherwise: this is the power of Gaia, which, in combination with complementary surveys, is further enhanced," concludes Timo Prusti, Gaia project scientist at ESA.


Detecting Gaia to provide the most accurate map ever of more than a billion stars


Further information:
F. Anders et al., Photo-astrometric Distances, Absorbances, and Astrophysical Parameters for Gaia DR2 Stars Lighter Than G = 18, Astronomy & Astrophysics (2019). DOI: 10.1051 / 0004-6361 / 201935765

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Quote :
Gaia Begins Mapping the Galactic Bar in the Milky Way (2019, July 16)
retrieved on 16 July 2019
from https://phys.org/news/2019-07-gaia-galactic-bar-milky.html

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