From Gemini Observatory: “Tiny Old Star Has Huge Impact”

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Gemini Observatory
From Gemini Observatory

November 5th, 2018

Media Contacts:

Peter Michaud
Public Information and Outreach manager
Gemini Observatory
Email: pmichaud”at”gemini.edu
Phone: 808-974-2510
Cell: 808-936-6643

Jill Rosen
Senior Media Relations Representative
Johns Hopkins University
Email: jrosen”at”jhu.edu
Desk: 443-997-9906
Cell: 443-547-8805

Science Contact:

Kevin Schlaufman
Assistant Professor of Physics and Astronomy
Johns Hopkins University
Email: kschlaufman”at”jhu.edu
Office Phone: 410-516-3295
Cell Phone: 814-490-9177

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The new discovery is only 14% the size of the Sun and is the new record holder for the star with the smallest complement of heavy elements. It has about the same heavy element proportion as Mercury, the smallest planet in our solar system. Credit: Kevin Schlaufman.

Astronomers use the Gemini Observatory to investigate a tiny star that is likely the oldest known star in the disk of our galaxy. The diminutive star could have a disproportionate impact on our understanding of the age and history of our Milky Way Galaxy. It also provides a unique glimpse into the conditions present in the young Universe shortly after the Big Bang.

A tiny star found in our galactic neighborhood is presenting astronomers with a compelling glimpse into the history of our galaxy and the early Universe. The star has some very interesting characteristics: it’s small, it’s old, and most significantly it’s made of material very similar to that spewed by the Big Bang. To host a star like this suggests that the disk of our galaxy could be up to three billion years older than previously thought.

“Our Sun likely descended from thousands of generations of short-lived massive stars that have lived and died since the Big Bang,” said Kevin Schlaufman of Johns Hopkins University, leader of this study published in the November 5th issue of The Astrophysical Journal. “However, what’s most interesting about this star is that it had perhaps only one ancestor separating it and the beginnings of everything,” Schlaufman adds.

The Big Bang theory dates our Universe at about 13.7 billion years and suggests that the first stars were made almost exclusively of hydrogen and helium. As stars die and gradually recycle their materials into new stars, heavier elements formed. Astronomers refer to stars which lack heavier elements as low metallicity stars. “But this one has such low metallicity,” said Schlaufman, “it’s known as an ultra metal poor star – this star may be one in ten million.”

The star, which goes by the designation 2MASS J18082002-5104378 B, also challenges the assumption that the first stars in the Universe were large, exclusively high-mass and short-lived stars. In addition, its location within the usually active and crowded disk of our galaxy is unexpected.

2MASS J18082002–5104378 B is a part of a binary star system. It is the smaller companion to a larger low-metallicity star observed in 2014 and 2015 by the European Southern Observatory’s Very Large Telescope UT2.

ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
•KUEYEN (UT2; The Moon ),
•MELIPAL (UT3; The Southern Cross ), and
•YEPUN (UT4; Venus – as evening star).
elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo

Before the discovery of the tiny star, astronomers mistakenly believed that this binary system might contain a black hole or neutron star. From April 2016 to July 2017, Schlaufman and his team used both the Gemini Multi-Object Spectrograph (GMOS) on the Gemini South telescope in Chile and the Magellan Clay Telescope at Las Campanas Observatory to dissect the star system’s light and measure the object’s relative motions, thus discovering the tiny star by detecting its gravitational tug on its partner.

Las Campanas Clay Magellan telescope, located at Carnegie’s Las Campanas Observatory, Chile, approximately 100 kilometres (62 mi) northeast of the city of La Serena, over 2,500 m (8,200 ft) high

Gemini Observatory GMOS on Gemini South

“Gemini was critical to this discovery, as its flexible observing modes enabled weekly check-ins on the system over six months,” Schlaufman confirms.

“Understanding the history of our own galaxy is critical for humanity to understand the broader history of the entire Universe,” said Chris Davis of the United State’s National Science Foundation (NSF). NSF funds the Gemini Observatory on behalf of the United States, additional international partners are listed at the end of this release.

2MASS J18082002–5104378 B has only about 14% the mass of our Sun making it a red dwarf star. While average-sized stars like our Sun live for approximately 10 billion years before extinguishing their nuclear fuel, low-mass stars can burn for trillions of years.

“Diminutive stars like these tend to shine for a very long time,” said Schlaufman. “This star has aged well. It looks exactly the same today as it did when it formed 13.5 billion years ago.”

The discovery of 2MASS J18082002–5104378 B gives astronomers hope for finding more of these old stars which provide a glimpse at the very early Universe. Only about 30 ultra metal poor stars have been identified. “Observations such as these are paving the way to perhaps one day finding that ever elusive first generation star,” concludes Schlaufman.

See the full article here.
See also the Monash University article here .


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Gemini/North telescope at Maunakea, Hawaii, USA,4,207 m (13,802 ft) above sea level

Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

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Gemini’s mission is to advance our knowledge of the Universe by providing the international Gemini Community with forefront access to the entire sky.

The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai’i (Gemini North) and the other telescope on Cerro Pachón in central Chile (Gemini South); together the twin telescopes provide full coverage over both hemispheres of the sky. The telescopes incorporate technologies that allow large, relatively thin mirrors, under active control, to collect and focus both visible and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in six partner countries with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the Canadian National Research Council (NRC), the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT), the Australian Research Council (ARC), the Argentinean Ministerio de Ciencia, Tecnología e Innovación Productiva, and the Brazilian Ministério da Ciência, Tecnologia e Inovação. The observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.