From Instituto de Astrofísica de Canarias – IAC via Manu Garcia: “Analyzing white dwarf known planetary orbiting fragments.”


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From Instituto de Astrofísica de Canarias – IAC

20/9/18
Paula Izquierdo
paula.izquierdo@iac.es

Planetesimal orbiting white dwarf WD 1145 + 017.
1
Artistic representation of a disk of dust and fragments planet around a star. Credit: NASA / JPL-Caltech.

The study, led by doctoral student of the Institute of Astrophysics of the Canary Islands (IAC) and the University of La Laguna (ULL) Paula Izquierdo, a deeper analysis of this particular white dwarf, which provides regular transits produced by remnants of planetary origin . It has been made from data obtained with the Gran Telescopio Canarias [see below] and the Liverpool Telescope.


2-metre Liverpool Telescope at La Palma in the Canary Islands, Altitude 2,363 m (7,753 ft)

Liverpool Telescope at the Observatorio del Roque de los Muchachos

An article recently published in the journal Monthly Notices of the Royal Astronomical Society (MNRAS) confirms the evolution of transits produced by the remains of a planetesimal orbiting the white dwarf WD 1145 + 017 . These “debris” pass in front of the star every 4.5 hours hiding from the light that is emitted, and are in continuous interaction and fragmentation, which results in significant changes in the depth and shape of transits observed .

Roque de los Muchachos Observatory (Garafía, La Palma). Credit IAC.

WD 1145 + 017 is a white dwarf: the remnant of a star that has exhausted all its nuclear fuel. Most white dwarfs have a smaller mass than the Sun and a similar size to Earth. Several studies indicate that 95% of all stars in the universe will end their lives turned into white dwarfs. Including our own sun.

“Studying this system can provide information about the future of our Solar System , ” says Paula Izquierdo, lead author of the work. Why WD 1145 + 017 is special. It is the first white dwarf in which changes were detected in the amount of light that comes from it, which are because of the light from the star is hidden by the fragments in continuous disintegration of a rocky body orbiting .

Although discovered in 2015, this system has attracted the attention of a large number of research teams. This latter work has, for the first time, spectroscopic data of Great Canary Telescope (10.4 m), photometric data obtained simultaneously with Liverpool Telescope (2 m), both installed in the Roque of the Boys (Garafía, La Palm).

“Outside of traffic flow we assume 100%, since nothing gets in the way of the light emitted from the white dwarf,” says researcher IAC / ULL. “But when there is material in orbit that passes between us and the star, adds, what happens in transit, the amount of light we receive is lower. This decrease is 50% in transit deeper we observed: there are clouds of dust as a result of the fragmentation of the planetesimal that are able to hide half the light of the white dwarf. ”

The study also confirms that transits in the visible range of the spectrum are gray. That is, there is no relationship between the depth of transit and the wavelength, so transits have the same depth in the five bands studied. The authors develop a new hypothesis where the flow would drop caused by an optically thick structure, at the expense of thin optically postulated above.

“The deepest transit has a complex structure that we have managed to model with overlapping different clouds of dust, as if it were six equally spaced fragments from the planetesimal,” says Pablo Rodríguez-Gil, co-author, IAC researcher and professor ULL.

Among other things, the team has also observed a decrease in the amount of absorption produced by iron during transit detected deeper. “Part of this absorption line says co-author Boris Gänsicke, a researcher at the University of Warwick (UK), does not originate in the atmosphere of the white dwarf, but in a disk of gas orbiting around this, so we show that the disc fragments and gas should be spatially correlated. ”

Finally, using the distance measured by the Gaia mission system, the computer has determined the mass, radius, temperature and age WD 1145 + 017.

ESA/GAIA satellite

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).
The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

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)

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