{"id":165912,"date":"2022-09-26T11:20:57","date_gmt":"2022-09-26T21:20:57","guid":{"rendered":"https:\/\/www.hawaii.edu\/news\/?p=165912"},"modified":"2022-09-26T11:22:02","modified_gmt":"2022-09-26T21:22:02","slug":"map-galaxies-largest-ever-catalog","status":"publish","type":"post","link":"https:\/\/www.hawaii.edu\/news\/2022\/09\/26\/map-galaxies-largest-ever-catalog\/","title":{"rendered":"糖心视频<\/abbr> astronomers map distances to 56,000 galaxies, largest-ever catalog"},"content":{"rendered":"Reading time: <\/span> 3<\/span> minutes<\/span><\/span>
\"Full-sky
Full-sky map showing Cosmicflows-4\u2019s 56,000 galaxies with distance measurements. Each dot represents a galaxy, and the color of the dot indicates distance from us.<\/figcaption><\/figure>\n

How old is our universe, and what is its size? A team of researchers led by University of Hawaiʻi<\/span> at M\u0101noa astronomers Brent Tully<\/strong> and Ehsan Kourkchi<\/strong> from the Institute for Astronomy<\/a> have assembled the largest-ever compilation of high-precision galaxy distances, called Cosmicflows-4. Using eight different methods, they measured the distances to a whopping 56,000 galaxies. The study is being published in the Astrophysical Journal<\/em>.<\/p>\n

\"Stephan\u2019s
Four galaxies in roughly a vertical line lie at 270 million light years strongly interact. The galaxy to the left, NGC 7320, lies to the foreground, 54 million light years away. Knowledge of the properties of these stars yields a distance to the galaxy. (Credit: NASA)<\/figcaption><\/figure>\n

Galaxies, such as the Milky Way, are the building blocks of the universe, each comprised of up to several hundred billion stars. Galaxies beyond our immediate neighborhood are rushing away, faster if they are more distant, which is a consequence of the expansion of the universe that began at the moment of the Big Bang. Measurements of the distances of galaxies, coupled with information about their velocities away from us, determine the scale of the universe and the time that has elapsed since its birth.<\/p>\n

“Since galaxies were identified as separate from the Milky Way a hundred years ago, astronomers have been trying to measure their distances,” said Tully. “Now by combining our more accurate and abundant tools, we are able to measure distances of galaxies, and the related expansion rate of the universe and the time since the universe was born with a precision of a few percent.”<\/p>\n

From the newly published measurements, the researchers derived the expansion rate of the universe, called the Hubble Constant, or H0. The team\u2019s study gives a value of H0=75 kilometers per second per megaparsec or Mpc<\/abbr> (1 megaparsec = 3.26 million light years), with very small statistical uncertainty of about 1.5%.<\/p>\n

There are a number of ways to measure galaxy distances. Generally, individual researchers focus on an individual method. The Cosmicflows program spearheaded by Tully and Kourkchi includes their own original material from two methods, and additionally incorporates information from many previous studies. Because Cosmicflows-4 includes distances derived from a variety of independent, distinct distance estimators, intercomparisons should mitigate against a large systematic error.<\/p>\n