From Instituto de Astrofísica de Canarias – IAC: “The observation of a rare hypernova, complete the story of the death of the most massive stars.

IAC

From Instituto de Astrofísica de Canarias – IAC

8/1/19
Manu Astrónomus

Contact:
Institute of Astrophysics of Andalusia (IAA-CSIC)
Dissemination and Communication Unit
Silbia Lopez de Lacalle – sll@iaa.es – 958230676
https://www.iaa.csic.es
https://divulgacion.iaa.csic.es

[I have done my best to correct the translation.]

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Explosion image obtained by the Gran Telescopio Canarias in the period of maximum brightness of the event.

A study led by the Institute of Astrophysics of Andalusia (IAA-CSIC) and published in Nature, studied in detail to the life of a star, which produces a gamma – ray burst (GRB) and a hypernovae.

The end of the life of stars holds placid scenarios in the case of low-mass stars like the sun. Not so in the case of very massive stars, which undergo explosive events so intense that they can get to outshine all the galaxy that hosts. An international group of astronomers has studied in detail the end of a massive star that has been a gamma-ray burst (GRB) and hypernovae, which has detected a new component in this type of phenomena. The study, published in the journal Nature [above], provides the link to complete the story that links hypernovae with GRBs.

“In 1998 the first hypernovae was detected, a version of the very energy supernovae, which followed a burst of gamma rays and which was the first evidence of the connection between the two phenomena” says Luca Izzo Institute investigator Andalusia Astrophysics (IAA-CSIC) headed the study.

The proposed scenario to explain the phenomenon involved a star of more than twenty solar masses, to exhaust their fuel undergoes a process of core collapse. To collapse on itself, the core generates a black hole or neutron stars, while two polar jets of matter that cross the outer layers of the star and, emerging into the medium, produce gamma ray bursts occur ( GRBs). Hypernovae finally burst, which can be tens of times more intense than a supernova occurs.

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Hypernovae artistic representation. The interaction of the jet
with the outer layers of the star forms a sheath around
the jet head and begins to spread laterally with respect
to the jet direction. The jet is able to completely pierce the
shell of the parent star, issue the issuance of a type of high – energy,
responsible for GRB. Source: Anna Serena Esposito.

But, even after twenty years of studying the relationship between GRBs and hypernovae seems clear, it is not met in the opposite direction, as they have detected several hypernovae not have associated gamma-ray bursts. “This work has allowed us to identify the missing link between these two subtypes hypernovae in the form of a new component: a kind of hot envelope is formed around the jet according propagates through the parent star -apunta Izzo (IAA CSIC) -. The jet transfers a significant part of its energy to the shell and, if it goes through the surface of the star will produce gamma ray emission we identify as GRB “.

However, the jet may spoil within the star and not emerge to medium lacking sufficient energy, a circumstance occurs hypernovae but not a GRB. Thus, the casing detected in this investigation represents the link between the two subtypes hypernovae studied so far, and these “jets damped” (English choked-jets) naturally explain the differences.

EVENT HISTORY

On December 5 the GRB171205A outbreak was detected in a galaxy located just five hundred million light years from Earth, making it the fourth GRB nearest known. “Phenomena of this kind occur on average once every ten years, so immediately began an intense campaign observation with the Gran Telescopio Canarias to observe the emerging hypernovae from the early stages -apunta Christina Thöne, researcher at the Institute of Astrophysics of Andalusia ( IAA-CSIC) participating in the hallazgo-. In fact, it is the earliest detection of a hypernovae to date, less than a day after the collapse of the star. ”

And indeed, once the first evidence of the presence of a hypernovae were observed. “This was possible because the luminosity of the jets was much weaker than normal because usually outshine the emission of the supernova He points during the first week Antonio de Ugarte Postigo, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) participating in the hallazgo-. However, a peculiar hypernovae, was already showing very high growth rates and a different chemical abundances to those recorded in similar events “.

This unique chemical composition and velocities associated fit the existence of a jet surrounded by an envelope that cuts on the surface of the star, which had been predicted earlier but had not yet observed. Sheath accompanying the jet during the first days drag material from the interior of the star, and in the case study allowed us to determine its chemical structure. After a few days, this comoponent disappeared and hypernovae evolved similarly to those observed previously.

The total energy emitted by the envelope was higher than the GRB, which implies that the jet deposited much of its energy in it. But also it shows that the energy of GRB depends on the interaction of the jet with stellar material and this new component, the wrapper. And also highlights the need to review the model: “While the standard model supernovae core collapse leads to nearly spherical explosions, evidence of such energy emission produced by a sheath of this type suggests that the jet plays an important role in central collapse supernovae, and we need to take into account the role of the jet explosion models of supernovae, “says Izzo (IAA-CSIC).

This study was coordinated by researchers from the group Phenomena Transients High Energy and Environment (High-Energy Transients and Their Hosts, HETH) of the IAA-CSIC. Christina headed by Thöne, studying the physics of transient astronomical phenomena, the environment in which they occur and the galaxies that host them.

See the full article here.


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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).

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