Researchers at the Instituto de Astrofisica de Canarias (IAC) and the University of Cambridge have detected lithium in a primitive star in our galaxy. The observations were made at the VLT, at the Paranal Observatory of ESO in Chile.
In astrophysics, any element heavier than hydrogen and helium is termed “metal” and lithium is among the lightest of these metals. Researchers at the IAC and the University of Cambridge have been able to detect lithium in a “primitive” star. This is the star J0023+0307, discovered a year ago by the same team of scientists with the Gran Telescopio Canarias (GTC) and the William Herschel Telescope (WHT) of the Observatorio del Roque de los Muchachos.
This discovery could give crucial information about the creation of atomic nuclei (“nucleosynthesis”) in the Big Bang. “This primitive star surprises us for its high lithium content, and its possible relation to the primordial lithium formed in the Big Bang,” notes David Aguado, a researcher associated with the University of Cambridge and formerly doctoral student of the IAC/ULL, who is the lead author on this article.
This star is similar to our Sun, but with a much poorer metal content, less than one thousandth part of that of the solar metallicity. This composition implies that we are dealing with a star which was formed in the first 300 million years of the universe, just after the supernovae marking the final phases of the first massive stars in our galaxy.
“The lithium content of this primitive star is similar to that of other metal poor stars in the halo of our galaxy, and they define, roughly, a constant value, independent of the value of the metal content of the star,” explains Jonay Gonzalez Hernandez, a Ramon y Cajal researcher at the IAC, a co-author of the article.
Lithium, synthesized in the Big Bang, is a very fragile metal which is easily destroyed in the interiors of stars by nuclear reactions at a temperature of 2,5 million degrees or above. As the base of the atmosphere of this type of metal-poor stars does not reach this temperature the lithium remains in them for practically the whole of their lives.
J0023+0307 is still on the main sequence, the phase in which stars remain for the greater part of their lives, and its age in almost that of the universe.
“Our star J0023+0307 retains this constant lithium content in a star with a very low metallicity, and so we understand that the lithium must have formed in an even earlier phase in the evolution of the universe,” adds Carlos Allende, an IAC researcher who is another author on the paper.
Orbit Logic reports it has delivered scheduling software to the National Oceanographic and Atmospheric Administration (NOAA) to optimize NOAA ground terminal contacts with Mid-Earth Orbit (MEO) satellites equipped to receive search and rescue distress alerts.
The solution helps improve the timeliness and location accuracy of distress alerts received by the satellites, leading to faster and more effective responses by rescue personnel. Orbit Logic’s delivered solution will include STK Scheduler for contact schedule optimization, STK Pro for system modeling, STK Coverage for Dilution of Precision (DoP) computations, as well as a custom software plug-in to coordinate computations and generate updated contact schedules on demand.
There are a growing number of MEO satellites equipped to receive search and rescue distress signals. Distress signals received by the satellites get relayed to NOAA ground terminals, which send the signals on to appropriate rescue organizations.
The number of MEO satellites on orbit now exceeds the number of NOAA ground terminals, so decisions need to be made about which satellites the terminals should point at to receive relayed distress calls.
Orbit Logic developed a COTS-based solution that uses STK Pro and STK Coverage to compute DoP for all possible satellite contact combinations, then passes this information to STK Scheduler. STK Scheduler uses this information to generate ground terminal pointing schedules optimized to provide the best possible geolocation accuracy of distress signals.
STK Scheduler models the system as a set of prioritized communications tasks with weighted preferences for resource (satellite) combinations over time. Scheduler generates a new, optimized contact schedule within seconds, allowing for quick updates as conditions change.
“We are honored to have been selected by NOAA for this important project that automates and optimizes contact scheduling in support of NOAA’s search and rescue mission.” said Alex Herz, president of Orbit Logic. “It is always a good feeling to know that your software is being deployed to help save lives.”
