From IAC: “IAC astronomers find a star in the Milky Way that shouldn’t really exist”


Instituto de Astrofísica de Canarias – IAC

Feb. 20, 2018

Artistic image of J0023 + 0307 star that was created in the early stages of the formation of the Milky Way. The J0023 + 0307 star formed from the first ejected by supernovas material. Credit: Gabriel Pérez, SMM (IAC).

Artistic image of supernova explosions of the first stars mass that formed in the Milky Way. Credit: Gabriel Pérez, SMM (IAC).

Scientists from the Instituto de Astrofísica de Canarias (IAC) have discovered the dwarf star J0023+0307, which is 9,450 light years away, in the halo of our Galaxy.

The article published today in the scientific journal The Astrophysical Journal Letters analyzes the primaeval chemical composition of this star. Because of its low metal content, and specifically its low carbon content this star “ throws doubt on the models of low mass star formation in the early universe” explains David Aguado, the first author of the paper.

This finding is similar to that made last December by the same group of observers, otra estrella enana, J0815+4729 also situated in the halo of the Milky Way and with low metallicity. In this new star, however, even carbon has not been detected, which makes its composition different from that normally found in similar stars.

otra estrella enana, J0815+4729

This is a challenge to the theoretical models of the formation of stars with low metallicity.

J0023+0307 is still on the Main Sequence, the stage in which stars remain for most of their lives, and has an age “virtually similar to that of the universe”, explains Jonay González González, a Ramón y Cajal research fellow of the IAC, and another author of the article. According to the established models for the formation of these stars their carbon content ought to be much bigger than those observed. For that reason “This star should not really exist” according to another IAC researcher, and the second author of this publication, Carlos Allende Prieto.

The instruments used

This observation was carried out using spectroscopy with the instruments ISIS and OSIRIS, on the William Herschel Telescope and the Gran Telescopio CANARIAS respectively.

ISIS Spectrograph on the ING William Herschel Telescope

ING 4 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands, 2,396 m (7,861 ft)

IAC Gran Telescopio Canarias OSIRIS spectrograph

Both telescopes are at the Roque de los Muchachos Observatory, in the municipality of Garafía (La Palma). The former has a primary mirror with 4.2m diameter, and the latter with a 10.4 m primary, made up of segments, which is one of the largest and most advanced optical-infrared telescopes in the world.

The next goal of the research programme for the science team at the IAC will be to try to detect other chemicla elements in the star, such as lithium and iron. Because the star is so old lithium in particular could give us crucial information about the production of atomic nuclei (“nucleosynthesis”) in the period just after the Big Bang.

To do this large telescopes, between 8m and 10 m diameter are needed, with spectrographs yielding high spectral resolution. The researchers are confident that the HORS spectrograph, now in a testing phase in the GTC, will in the near future be used for the chemical analysis of faint stars such as J0023+0307 y J0815+4729.

See the full article here.

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Roque de los Muchachos Observatory is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands, at an altitude of 2,396 m (7,861 ft)

Stem Education Coalition
The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
The Centro de Astrofísica en La Palma (CALP)
The Observatorio del Teide (OT), in Izaña (Tenerife).
The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

The IAC’s research programme includes astrophysical research and technological development projects.

The IAC is also involved in researcher training, university teaching and outreachactivities.

The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.

Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC