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  • richardmitnick 9:39 am on November 25, 2021 Permalink | Reply
    Tags: "Astronomers discover ancient brown dwarf with lithium deposits intact", , , , Brown dwarf called Reid 1B, , IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “Astronomers discover ancient brown dwarf with lithium deposits intact” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    24/11/2021
    Contacts:
    Dr. Eduardo Martín Guerrero,
    Dr. Carlos del Burgo

    1
    The Spanish-Mexican team has found that the boundary between those objects which destroy lithium and those which preserve it lies at 51.5 times the mass of Jupiter. The brown dwarf Reid 1B is a major deposti of lithium which will never be destroyed. Planets such as Jupiter and the Earth are even less massive and do not destroy their lithium. The Sun has destroyed all the lithium that was in its nucleus and preserves some in its upper layers, which are slowly mixing with its interior. Credit: Gabriel Pérez Díaz, SMM (IAC).

    A team of researchers at The National Institute for Astrophysics, Optics and Electronics(MX), has discovered lithium in the oldest and coldest brown dwarf where the presence of this valuable element has been confirmed so far. This substellar object, called Reid 1B, preserves intact the earliest known lithium deposit in our cosmic neighbourhood, dating back to a time before the formation of the binary system to which it belongs. The discovery was made using the OSIRIS spectrograph on the Gran Telescopio Canarias (GTC) [below], at The Roque de los Muchachos Observatory | Instituto de Astrofísica de Canarias • IAC(ES),[below] in the Canary Islands.

    IAC Gran Telescopio Canarias OSIRIS spectrograph.

    The study has just been published in the journal MNRAS.


    Comparación entre las masas dinámicas y termonucleares en sistemas binarios de enanas marrones. Más información: http://www.iac.es.

    Brown dwarfs, also known as “coffee coloured dwarfs” or “failed stars” are the natural link between stars and planets. They are more massive than Jupiter but now sufficiently to burn hydrogen, which is the fuel the stars use to shine. For that reason these substellar objects were not observed until observers detected them in the mid 1990’s. They are particularly interesting because it was predicted that some of them could preserve intact their content of lithium, sometimes known as “white petroleum” because of its rarity and its relevance.

    In the past twenty years astronomers have detected, and followed the orbital motions of binaries formed by brown dwarfs in the solar neighbourhood. They have determined their masses dynamically using Kepler’s laws, the mathematical formulae produced in the XVII century by Johannes Kepler to describe the motions of astronomical bodies moving under the effects of their mutual gravitation, such as the system formed by the Earth and the Sun. In some of these systems the primary component has a mass sufficient to burn lithium while the secondary may not have this mass. However until now the theoretical models had not been put to the test.

    Using the OSIRIS spectrograph on the Gran Telescopio Canarias (GTC, or Grantecan) currently the largest optical and infrared telescope in the world, at the Roque de los Muchachos Observatory (ORM), a team of researchers at the Instituto de Astrofísica de Canarias (IAC) and the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) made high sensitivity spectroscopic observations, between February and August this year, of two binaries whose components are brown dwarfs.

    They did not detect lithium in three of them, but they did find it in Reid 1B, the faintest and coolest of the four. Doing this they made a remarkable discovery, a deposit of cosmic lithium which is not destroyed, whose origin dates back before the formation of the system to which Reid 1B belongs. It is, in fact, the coolest, faintest extrasolar object where lithium has been found, in a quantity 13 thousand times greater than the amount there is on Earth. This object, which has an age of 1.100 million years, and a dynamical mass 41 times bigger than that of Jupiter (the largest planet in the Solar System), is 16.9 light years away from us.

    A chest of hidden treasure

    Observations of lithium in brown dwarfs allow us to estimate their masses with a degree of accuracy, based on nuclear reactions. The thermonuclear masses found this way must be consistent with the dynamical masses found, with less uncertainty, from orbital analysis. However the researchers have found that the lithium is preserved up to a dynamical mass which is 10% lower than that predicted by the most recent theoretical models. This discrepancy seems to be significant, and suggests that there is something in the behaviour of brown dwarfs that we still don’t understand.

    “We have been following the trail of lithium in brown dwarfs for three decades” says Eduardo Lorenzo Martín Guerrero de Escalante, Research Professor of the Higher Council for Scientific Research (CSIC) at the IAC who is the first author of the article, “and finally we have been able to make a precise determination of the boundary in mass between its preservation and its destruction, and compare this with the theoretical predictions”. The researcher adds that “there are thousands of millions of brown dwarfs in the Milky Way. The lithium contained in brown dwarfs is the largest known deposit of this valuable element in our cosmic neighbourhood”.

    Carlos del Burgo Díaz co-author of the article, a researcher at the INAOE, a public research centre of the Mexican CONACYT, explains that “although primordial lithium was created 13.800 million years ago, together with hydrogen and helium, as a result of he nuclear reactions in the primordial fireball of the Big Bang, now there is as much as four times more lithium in the Universe”. According to this researcher “although this element can be destroyed, it is also created in explosive events such as novae and supernovae, so that brown dwarfs such as Reid 1B can wrap it up and protect it as if it was a chest of hidden treasure”.

    This research has been financed by funding from the Spanish Ministry of Economic Affairs and Digital Transformation (MINECO) and by the European Fund for Regional Developomente (FEDER) via project PID2019-109522GB-C53.

    The Gran Telescopio Canarias, and the Observatories of the Instituto de Astrofísica de Canarias (IAC) are part of the network of Singular Scientific and Technical Infrastructures (ICTS) of Spain.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The Instituto de Astrofísica the headquarters, which is in La Laguna (Tenerife).

    Observatorio del Roque de los Muchachos at La Palma (ES) at an altitude of 2400m.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft).

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    Isaac Newton Group 4.2 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands(ES), 2,396 m (7,861 ft).

    The Swedish 1m Solar Telescope SST at the Roque de los Muchachos observatory on La Palma Spain, Altitude 2,360 m (7,740 ft).

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Tiede Observatory, Tenerife, Canary Islands (ES)

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 11:36 am on November 17, 2021 Permalink | Reply
    Tags: "Characterization of the host galaxy from gamma-ray blazars", , , , IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES), Very high energy gamma rays   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “Characterization of the host galaxy from gamma-ray blazars” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    16/11/2021

    Josefa Becerra González
    José Antonio
    Acosta Pulido
    W. Boschin
    Telescopio Nazionale Galileo – La Palma [below]

    Rosa Clavero Jiménez
    Jorge Otero Santos
    J. A. Carballo-Bello
    University of Tarapacá [Universidad de Tarapacá – Universidad del Estado](CL)

    L. Domínguez-Palmero
    Isaac Newton Group of Telescopes- La Palma

    1
    Optical spectrum from the VHE gamma-ray blazar S4 0954+65. The detection of the emission lines allows us to firmly establish the redshift and the characteristics of the source.

    The most extreme electromagnetic radiation that can be observed is known as very high energy gamma rays (VHE, E>100 GeV). It is the last window open to the Universe, thanks to the development of the Čerenkov telescopes. The extragalactic VHE sky is still nowadays vastly unexplored, only composed of around 80 known sources. The great majority of them are classified as blazars, a type of Active Galactic Nuclei (AGN) whose relativistic jets point in the direction of the Earth boosting their emission. While the observation of the gamma-ray emission is crucial to understand the extreme physical mechanisms taking place at the relativistic jets from blazars, the optical characterization of their host galaxies plays a key role in the study of this extreme cosmological sources. There are mainly three aspects for which optical spectroscopic observations are key. The first one is the distance (redshift) of the target, that can only be derived confidently from the optical emission/absorption spectral features. Gamma rays are absorbed when interacting with the low energy diffuse photon fields (Extragalactic Background Light) in their way to the Earth. Such absorption strongly depends on the distance of the source, and therefore the redshift is key to infer the intrinsic gamma-ray emission. The second item is related to the characteristics of the optical emission lines, as they are a proxy to characterize the Broad Line Region (BLR), which photon field can induce gamma-ray absorption. The last important item is that extreme blazars emission peaks at higher energies, unveiling the host galaxy emission. Therefore, their optical spectrum allow us to probe the stellar population which is typically hidden due to the strong emission from their relativistic jets. In this work, the distance for three VHE gamma-ray blazars have been estimated firmly for the first time. The spectroscopic campaign during different flux states on S4 0954+65 was key to detect the weak emission lines. The continuum emission from the jet typically outshines the host galaxy, making very challenging the detection of spectral features. Therefore, the observation during the jet low flux states is important for the detection of weak spectral features. The stellar population has been also investigated for the VHE blazars TXS 1515−273 and RX J0812.0+0237, in both cases present an old and metallic stellar population, characteristics of giant elliptical galaxies.

    Science paper:
    MNRAS

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The Instituto de Astrofísica the headquarters, which is in La Laguna (Tenerife).

    Observatorio del Roque de los Muchachos at La Palma (ES) at an altitude of 2400m.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft).

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    Isaac Newton Group 4.2 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands(ES), 2,396 m (7,861 ft).

    The Swedish 1m Solar Telescope SST at the Roque de los Muchachos observatory on La Palma Spain, Altitude 2,360 m (7,740 ft).

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Tiede Observatory, Tenerife, Canary Islands (ES)

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 7:23 pm on October 19, 2021 Permalink | Reply
    Tags: "CLASP2.1- a new suborbital space mission for mapping the magnetic field of the solar chromosphere", CLASP and CLASP2 missions, IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES), Sounding rockets carry instruments into space for only a few minutes before falling back down to Earth., , The chromosphere is a key region of the solar atmosphere where magnetic forces start to dominate the behavior of the plasma., The chromosphere is located between the relatively cool and thin photosphere and the very extended and extremely hot corona., The CLASP sounding rocket experiments represent a milestone in astrophysics.   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “CLASP2.1- a new suborbital space mission for mapping the magnetic field of the solar chromosphere” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    18/10/2021

    Javier Trujillo Bueno
    jtb@iac.es

    Ernest Alsina Ballester
    ealsina@iac.es

    Tanausú del Pino Alemán
    tanausu@iac.es

    In 2015 and 2019 an international team (USA, Japan and Europe) carried out two unprecedented suborbital space experiments called CLASP and CLASP2, which were motivated by theoretical investigations carried out at the IAC. After the success of such missions, the team has just launched CLASP2.1 from the NASA facility in White Sands Missile Range (New Mexico, USA). The aim is to map the solar magnetic field throughout the chromosphere of an active region. To this end, CLASP2.1 has successfully measured the intensity and polarization of the solar ultraviolet radiation emitted by magnesium and manganese atoms, which can only be observed above the Earth’s atmosphere.

    Sounding rockets carry instruments into space for only a few minutes before falling back down to Earth, but they allow to achieve new scientific breakthroughs and discoveries at a relatively low cost. This is what the previous CLASP and CLASP2 missions did while opening a new exploration window in solar and stellar physics: ultraviolet spectropolarimetry. By measuring the polarization (a property of the electromagnetic radiation related to the orientation of its electric field) that some physical mechanisms introduce in the ultraviolet radiation emitted by the hot plasma of the solar chromosphere, it is possible to obtain information on the geometry of the plasma and its magnetism. The chromosphere is a key region of the solar atmosphere where magnetic forces start to dominate the behavior of the plasma. With an extension of a few thousands kilometers, the chromosphere is located between the relatively cool and thin photosphere and the very extended and extremely hot corona.

    1
    Figure 1: The region of the solar disk observed by CLASP2.1. The white rectangles in the lower right inset images of both panels indicate the area where the intensity and polarization of the ultraviolet radiation has been measured.

    The Chromospheric LAyer Spectro-Polarimeter 2.1 (CLASP2.1) is the third trip of the CLASP instrument to space. In 2019 CLASP2 could measure for the first time the polarization of the ultraviolet radiation emitted by the magnesium ions and the manganese atoms of the solar chromosphere, from which the magnetic field could be determined at each position along a fixed direction on the solar disk.

    The aim of CLASP2.1 is to obtain a full map of the magnetic field that permeates the chromosphere of active regions, such as that shown in figure 1. To this end, on 2021 October 8 CLASP2.1 scanned the area indicated in the figure, measuring the intensity and polarization of the emitted ultraviolet radiation at each spatial point. A video of the CLASP2.1 observation can be seen at the end of this press release.

    The CLASP sounding rocket experiments represent a milestone in astrophysics. They have demonstrated that the theoretically predicted polarization signals can be measured with today’s technology and that they allow us to determine the magnetic field throughout the whole solar chromosphere, including the base of the super-hot corona. “Space agencies worldwide can now be sure that the development of space telescopes equipped with instruments like CLASP would lead to major new advances and discoveries in solar and stellar physics”, comments Javier Trujillo Bueno, one of the four principal investigators of these pioneering space experiments.


    CLASP2.1 observation. Credit: CLASP2.1.

    The Principal Investigators of the CLASP-2 project are:

    David McKenzie (NASA Marschall Space Flight Center, USA)
    R. Ishikawa (National Astronomical Observatory of Japan, Japan)
    Fréderick Auchere (Institut d’Astrophysique Spatiale, France)
    Javier Trujillo Bueno (Instituto de Astrofísica de Canarias, Spain)

    CLASP2.1 is an international collaboration led by NASA’s Marshall Space Flight Center (US), The National Astronomical Observatory of Japan [国立天文台](JP), the Instituto de Astrofísica de Canarias (IAC, Tenerife, Spain) and The Institute of Space Astrophysics France [Institut d’Astrophysique Spatiale France](FR). Additional members are The IRSOL – Istituto Ricerche Solari, Locarno[CH] , the Astronomical Institute of the
    Czech Academy of Sciences – Akademie věd České republiky [CZ], Lockheed Martin Solar & Astrophysics Laboratory (USA), Stockholm University [Stockholms universitet](SE) and The Rosseland Centre for Solar Physics[Senter for Fremragende Forskning](NO).

    The IAC participation in CLASP2 receives funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Advanced Grant agreement No. 742265).

  • See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The Instituto de Astrofísica the headquarters, which is in La Laguna (Tenerife).

    Observatorio del Roque de los Muchachos at La Palma (ES) at an altitude of 2400m.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft).

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    Isaac Newton Group 4.2 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands(ES), 2,396 m (7,861 ft).

    The Swedish 1m Solar Telescope SST at the Roque de los Muchachos observatory on La Palma Spain, Altitude 2,360 m (7,740 ft).

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Tiede Observatory, Tenerife, Canary Islands (ES)

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

 
  • richardmitnick 9:16 pm on October 14, 2021 Permalink | Reply
    Tags: "Rocky exoplanets and their host stars may have similar composition", , , , , IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “Rocky exoplanets and their host stars may have similar composition” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    14/10/2021

    Garik Israelian
    gil@iac.es

    1
    Illustration of the formation of a planet round a star similar to the Sun, with rocks and iron molecules in the foreground. Credit: Tania Cunha (Harbor Planetarium [Planetário do Porto](PT) – Centro Ciência Viva & Instituto de Astrofísica e Ciências do Espaço).

    Newly formed stars have protoplanetary discs around them. A fraction of the material in the disc condenses into planet-forming chunks, and the rest finally falls into the star. Because of their common origin, researchers have assumed that the composition of these chunks and that of the rocky planets with low masses should be similar to that of their host stars. However, until now the Solar System was the only available reference for the astronomers.

    In a new research article, published today in the journal Science, an international team of astronomers led by the researcher Vardan Adibekyan, of The Instituto de Astrofísica e Ciências do Espaço (IA), with participation by the Instituto de Astrofísica de Canarias (IAC), has established for the first time a correlation between the composition of rocky exoplanets and that of their host stars. The study also shows that this relation does not correspond exactly to the relation previously assumed.

    “The team found that the composition of rocky planets is closely related to the composition of their host stars, which could help us to identify planets which may be similar to ours”, explains Vardan Adibekyan, the first author on the paper. “In addition, the iron content of these planets is higher than that predicted from the composition of the protoplanetary discs from which they formed, which is due to the specific characteristics of the formation processes of planets, and the chemistry of the discs. Our work supports models of planet formation and a level of certainty and detail without precedent”, he added.

    For Garik Israelian, an IAC researcher and co-author of the article, this result could not have been imagined in the year 2000. “At that time we tried to find a correlation between the chemical composition of certain solar type stars and the presence of planets orbiting them (or of their orbital characteristics). It was hard to believe that twenty years later these studies would grow to include the metal abundances of planets similar to the Earth”, he emphasises.

    “For us this would have seemed to be science fiction. Planets similar to the Earth were not yet known, and we concentrated only on the planets we could find, and on the parameters of their orbits around their host stars. And today, we are studying the chemical composition of the interiors and of the atmospheres of extrasolar planets. It is a great leap forward”, he added.

    To establish the relation, the team selected twenty-one rocky planets which had been characterized most accurately, using their measurements of mass and radius to determine their densities and their iron content. They also used high-resolution spectra from the latest generation of spectrographs in the major world observatories: at Mauna Kea (Hawaii), at La Silla and Paranal (Chile) and at the Roque de los Muchachos, (Garafía, La Palma, Canary Islands), to determine the compositions of their host stars, and of the most critical components for the formation of rocks in the protoplanetary discs.

    “Understanding the link in the composition between the stars and their planets has been a basic aspect of research in our centre for over a decade. Using the best high-resolution spectrographs, such as HARPS and ESPRESSO at the European Southern Observatory (ESO), our team has collected spectra of the host stars of exoplanets for several years.

    These spectra were used to determine the stellar parameters and abundances of the host stars, and the results have been put together in the published catalogue SWEET-Cat”, explained Nuno Santos, a researcher at the IA and a co-author of the article.

    The team also found an intriguing result. They found differences in the fraction of iron between the super earths and super mercurys, which implies that these planets seem to constitute different populations in terms of composition, with further implications for their formation. This finding will need more studies, because the simulations of the formation of planets, incorporating collision, cannot by themselves reproduce the super mercurys of high density. “Understanding the formation of the super mercurys will help us to understand the especially high density of Mercury”, Adibekyan assures us.

    This research was carried out in the framework of the project “Observational Tests of the Processes of Nucleosynthesis in the Universe” started in the year 2000 by the IAC researcher Garik Israelian; Michel Mayor, Nobel Laureate in Physics, 2019; and Nuno Santos, researcher at the IA.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft)

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 9:43 pm on October 13, 2021 Permalink | Reply
    Tags: "Einstein’s Principle of Equivalence verified in quasars for the first time", , , , , IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES),   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “Einstein’s Principle of Equivalence verified in quasars for the first time” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    13/10/2021

    Evencio Mediavilla
    emg@iac.es

    1
    Artist impression of a quasar. Credit: M. Kornmesser/ European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte](EU)(CL)

    According to Einstein’s theory of general relativity gravity affects light as well as matter. One consequence of this theory, based on the Principle of Equivalence, is that the light which escapes from a region with a strong gravitational field loses energy on its way, so that it becomes redder, a phenomenon known as the gravitational redshift. Quantifying this gives a fundamental test of Einstein’s theory of gravitation. Until now this test had been performed only on bodies in the nearby universe, but thanks to the use of a new experimental procedure scientists at the Instituto de Astrofísica de Canarias (IAC) and The University of Granada [Universidad de Granada] (ES) have been able to measure the gravitational redshift in quasars, and thus extend the test to very distant regions from where the light was emitted when our universe was young.

    Einstein’s Principle of Equivalence is the cornestone of the General Theory of Relativity, which is our best current description of gravity, and is one of the basic theories of modern physics. The principle states that it is experimentally impossible to distinguish between a gravitational field and an accelerated motion of the observer, and one of its predictions is that the light emitted from within an intense gravitational field should undergo a measurable shift to lower spectral energy, which for light means a shift to the red, which is termed “redshift”.

    This prediction has been well and very frequently confirmed close to the Earth, from the first measurements by R.V. Pound and G.A. Rebka at Harvard in 1959 until the most recent measurements with satellites. It has also been confirmed using observations of the Sun, and of some stars, such as our neighbour Sirius B, and the star S2 close to the supermassive black hole at the centre of the Galaxy. But to confirm it with measurements beyond the Galaxy has proved difficult, and there have been only a few tests with complicated measurements and low precision in clusters of galaxies relatively near to us in cosmological terms.

    The reason for this lack of testing in the more distant universe is the difficulty of measuring the redshift because in the majority of situations the effect of gravity on the light is very small. For that reason massive black holes with very strong gravitational fields offer promising scenarios for measuring gravitational redshifts. In particular the supermassive black holes found at the centres of galaxies, which have huge gravitational fields, offer one of the more promising scenarios to measure the gravitational redshift. They are situated at the centres of the extraordinarily luminous and distant quasars.

    A quasar is an object in the sky which looks like a star but is situated at a great distance from us, so that the light we receive from it was emitted when the universe was much younger than now. This means that they must be extremely bright. The origin of this huge power output is a disc of hot material which is being swallowed by the supermassive black hole at its centre. This energy is generated in a very small region, barely a few light days in size.

    In the neighbourhood of the black hole there is a very intense gravitational field and so by studying the light emitted by the chemical elements in this region (mainly hydrogen, carbon, and magnesium) we would expect to measure very large gravitational redshifts. Unfortunately the majority of the elements in quasar accretion discs are also present in regions further out from the central black hole where the gravitational effects are much smaller, so the light we receive from those elements is a mixture in which it is not easy to pick out clearly the gravitational redshifts.

    The measurements cover 80% of the history of the universe

    Now a team of researchers at the Instituto de Astrofísica de Canarias (IAC) and the University of Granada (UGR) have found a well defined portion of he ultraviolet light emitted by iron atoms from a region confined to the neighbourhood of the black hole. “Through our research related to gravitational lensing, another of the predictions of Einstein’s theory of General Relativity, we found that a characteristic spectal feature of iron in quasars seemed to be coming from a region very close to the black hole. Our measurements of the redshift confirmed this finding” explains Evencio Mediavilla, an IAC researcher, Professor at the Unversity of La Laguna(ULL) and first author of the article.

    Using this feature the researchers have been able to measure clearly and precisely the gravitational redshifts of many quasars and, using them, estimate the masses of the black holes. “This technique marks an extraordinary advance, because it allows us to measure precisely the gravitational redshifts of individual objects at great distances, which opens up important possibilities for the future” says Mediavilla.

    Jorge Jimenez Vicente, a researcher at the UGR, and co-author of the article, stressess the implications of this new experimental procedure, as it allows comparison of the measured redshift with the theoretcially predicted value: “this technique allows us for the first time to test Einstein’s Principle of Equivalence, and with it the basis of our understanding of gravity on cosmological scales.”

    This test of the Principle of Equivalence performed by these researchers is based on measurements which include active galaxies in our neighbourhood (some 13,800 million years after the Big Bang) out to individual quasars a large distances, whose light was emitted when the age of the universe was only some 2,200 million years, thus covering around 80% of the history of the universe. “The results, with a precision comparable to those of experiments carried out within our Galaxy, validate the Principle of Equivalence over this vast period of time” notes Jiménez-Vicente.

    The article has been published in the journal The Astrophysical Journal, and recently has been selected by The American Astronomical Society (US) which as published an interview with the researchers in the section “AAS Journal Author Series” of its YouTube channel, whose aim is to link the authors with their article, their personal histories, and the astronomical community in general.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft)

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 9:21 am on September 28, 2021 Permalink | Reply
    Tags: , IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES),   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “IRSOL and IAC scientists solve a complex paradox in solar physics” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    18/08/2021

    Ernest Alsina Ballester
    ernest.alsina@iac.es

    Javier Trujillo Bueno
    jtb@iac.es

    In 1998, the journal Nature published a seminal letter concluding that the mysterious polarization signal that had been recently discovered in the light emitted by the sodium atoms of the solar atmosphere implies that the solar chromosphere (a very important layer of the solar atmosphere) is practically unmagnetized, in sharp contradiction with common wisdom. This paradox motivated laboratory experiments and theoretical investigations, which instead of providing a solution, raised new issues and even led some scientists to question the quantum theory of radiation-matter interaction. In an article published and highlighted today by the prestigious Physical Review Letters, Ernest Alsina Ballester (IRSOL – Istituto Ricerche Solari, Locarno, and IAC), Luca Belluzzi (IRSOL) and Javier Trujillo Bueno (IAC) show the solution to such intriguing paradox, which has puzzled solar physicists over the last decades. This research opens up a new window for exploring the elusive magnetic fields of the solar chromosphere in the present new era of large-aperture solar telescopes.

    Twenty-five years ago, an enigmatic signal was discovered [Nature] while analyzing the polarization of sunlight with a new instrument, the Zurich Imaging Polarimeter (ZIMPOL).

    This mysterious linear polarization signal appears at the 5896 Å wavelength of the D1 line of neutral sodium where, according to the line’s quantum numbers, no linear polarization due to scattering processes should be present. This polarization signal was therefore totally unexpected, and its interpretation immediately opened an intense scientific debate. The mystery further increased two years later, when the journal Nature published a letter with an explanation, which required that the sublevels of the lower level of the D1 line are not equally populated. In that theoretical work, the enigmatic polarization signal of the D1 line was reproduced remarkably well. However, the proposed explanation implied that the region of the solar atmosphere known as the chromosphere is completely unmagnetized, in apparent contradiction with established results, which instead indicate that the quiet regions (outside sunspots) of the solar chromosphere are permeated by magnetic fields in the gauss range. This opened a serious paradox, which has challenged solar physicists for many years, and even led some scientists to question the quantum theory of atom-photon interactions.

    A first breakthrough towards the resolution of the paradox was achieved in 2013 at the IAC, when Luca Belluzzi and Javier Trujillo Bueno theoretically discovered a new mechanism through which linear polarization can be produced in the sodium D1 line without the need of population imbalances in the lower level of the D1 line. However, that important step given by these researchers was for the idealized case of a solar atmosphere model without magnetic fields.

    2
    Figure 1: Variation with wavelength of the linear polarization (Q/I) of sunlight across the solar sodium D1 and D2 spectral lines (left panel) and across D1 (right panel). The black curves indicate the observed signals (the measurements were carried out at IRSOL with the ZIMPOL instrument). The red and blue curves show the results of theoretical calculations carried out neglecting (red) and including (blue) magnetic fields. An excellent agreement between the observation and the theoretical modeling is obtained when assuming that the quiet regions (outside sunspots) of the solar chromosphere are permeated by a magnetic field of 15 gauss.

    In an article published today by Physical Review Letters, the prestigious scientific journal of the American Physical Society, Ernest Alsina Ballester, Luca Belluzzi, and Javier Trujillo Bueno show the solution to this intriguing paradox, which has puzzled solar physicists since 1998. As shown in figure 1, this team of researchers has been able to reproduce the enigmatic observations of the D1 line polarization, in the presence of magnetic fields in the gauss range. To achieve this result, it was necessary to carry out the most complete theoretical modeling of this polarization signal ever attempted, accounting for the joint action of very complex physical mechanisms. This required three years of work, carried out through a close cooperation between the Istituto Ricerche Solari (IRSOL) in Locarno-Monti (affiliated to the Università della Svizzera italiana) and the POLMAG group of the Instituto de Astrofísica de Canarias (IAC) in Tenerife.

    See http://research.iac.es/proyecto/polmag/

    This result has very important consequences. Linear polarization signals, like the one observed in the D1 line of sodium, are extremely interesting because they encode unique information on the elusive magnetic fields present in the solar chromosphere. This key interface layer of the solar atmosphere, located between the underlying cooler photosphere and the overlying million-degree corona, is at the core of several enduring problems in solar physics, including the understanding and prediction of the eruptive phenomena that may strongly impact our technology-dependent society. The magnetic field is known to be the main driver of the spectacular dynamical activity of the solar chromosphere, but our empirical knowledge of its intensity and geometry is still largely unsatisfactory. The solution of the long-standing paradox of solar D1 line polarization proves the validity of the present quantum theory of spectral line polarization, and opens up a new window to explore the magnetism of the solar atmosphere in the present new era of large-aperture solar telescopes.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The Instituto de Astrofísica the headquarters, which is in La Laguna (Tenerife).

    Observatorio del Roque de los Muchachos at La Palma (ES) at an altitude of 2400m.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft)

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    Isaac Newton Group 4.2 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands(ES), 2,396 m (7,861 ft)

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 1:38 pm on September 4, 2021 Permalink | Reply
    Tags: "Dust in the central parsecs of unobscured AGN provide more challenges to the torus", IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES), , , ,   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “Dust in the central parsecs of unobscured AGN provide more challenges to the torus” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    04/09/2021

    M Almudena, Prieto Escudero, J. Nadolny
    Instituto de Astrofísica de Canarias (IAC)

    J. A. Fernández-Ontiveros
    Istituto di Astrofisica e Planetologia Spaziali (IT)

    M. Mezcua
    Institute of Space Studies of Catalonia [Institut d’Estudis Espacials de Catalunya](ES)

    1
    The image shows the process of nuclear feeding of a black hole in the galaxy NGC 1566, and how the dust filaments – seen in white-blue colors- are trapped and rotating in a spiral around the black hole until the black hole swallows them. Credit: ESO.

    The black holes at the centres of galaxies are the most mysterious objects in the Universe, not only because of the huge quantities of material within them, millions of times the mass of the Sun, but because of the incredibly dense concentration of matter in a volume no bigger than that of our Solar System. When they capture matter from their surroundings they become active, eventually giving rise to the ejection of huge amounts of energy. It is however difficult to detect the black hole during these capture episodes because the event is rare. We detected long and narrow dust filaments surrounding and feeding the black hole in the centres of several galaxies. These filaments could furthermore be the natural cause of the darkening of the centre of many galaxies when their nuclear black holes become active. The discovery of these filaments and the understanding of their nature have been made possible by using extremely sharp images obtained with the Hubble Space Telescope, the Very Large Telescope (VLT) at the European Southern Observatory (ESO), and the Atacama Large Millimetre Array (ALMA) in Chile.

    Each of these images provides us with a different view of the various states of the interstellar medium in which these filaments reside. Their combined analysis led to a direct visualisation of filaments feeding the black hole. A first estimate of the amount of matter in the filaments indicates an inflow equivalent to the mass of the Sun per year.

    Science paper:
    MNRAS

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft)

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 10:17 am on September 4, 2021 Permalink | Reply
    Tags: "Anatomy of the impact of a protostellar jet in the Orion Nebula", , , , HH204-a Herbig-Haro object in the Orion Nebula, IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES), ,   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “Anatomy of the impact of a protostellar jet in the Orion Nebula” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    02/09/2021

    1
    View of HH204-a Herbig-Haro object in the Orion Nebula. The left panel shows the Orion Nebula observed with the Hubble Space Telescope, picking out the area around HH204. In the right panel, we can see in detail the structure of HH204 and of its apparent companion, HH203. In this panel, the images by the Hubble Space Telescope taken during 20 years and artificially highlighted with different colours show the advance of the jets of gas through the Orion Nebula. Credit: Gabriel Pérez Díaz, SMM (IAC).

    An international team led by researchers from the Instituto de Astrofísica de Canarias (IAC) has uncovered, with an new high degree of detail, the physical and chemical effects of the impact of a protostellar jet in the interior of the Orion Nebula. The study was made using observations with the Very Large Telescope (VLT) and 20 years of images with the NASA/ESA Hubble Space Telescope (HST).

    The observations show evidence of compression and heating produced by the shock front, and the destruction of dust grains, which cause a dramatic increase in the gas phase abundance of the atoms of iron, nickel, and other heavy elements in the Orion Nebula. The results were recently published in The Astrophysical Journal.

    The Orion Nebula, one of the known and brightest objects in the night sky, is the nearest region of massive star formation to Earth, and it has a complex and extensive gas structure.

    Some of the newborn stars within it emit jets of gas at high speed which, when they impact their surroudings, produce shock fronts which compress and heat the nebular gas. These impact zones are bow-shaped, and are called Herbig-Haro objects, after their discoverers, the US astonomer George Herbig, and the Mexican astronomer Guillermo Haro.

    These objects have been observed previously in many dark nebulae, where the cold gas is neutral, and its main source of energy is the heat generated by the shock. However, the jets of gas in the Orion Nebula are immersed in a large radiation field produced by the most massive stars in the Trapezium of Orion, situated at the centre of the nebula. Due to this radiation the gas within the shock front and also the gas compressed after it has passed through, is warm and ionized, and this allows us to measure precisely the physical conditions and the chemical composition of the jet.

    The research carried out by a team of astronomers in Spain, Mexico and the United States, led by José Eduardo Méndez Delgado, a doctoral student at the IAC and the University of La Laguna [Universidad de La Laguna](ES), has uncovered the complex relations between the ionic abundances of the gas and its physical conditions in HH204, one of the most prominent Herbig-Haro objects in the Orion Nebula.

    “Our work shows that the in the shock front of HH204 the gas abundances of heavy elements such as iron and nickel are increased by up to 350% compared to the values usually found in the Orion Nebula, and this allows us to determine the proportion of other chemical elements more accurately, which contributes to an improved knowledge of the chemical evolution in the solar neighbourhood”, explains José Eduardo Méndez Delgado, the first author of the article.

    “As well as the heavy element enrichment in the gas phase, we have observed a heated post-shock zone which comprises a very small fraction of the gas, and which lets us understand the different layers of the structure of the Herbig-Haro object generated by the impact of the shock front”, says César Esteban, and IAC researcher and a co-author of the article.

    “The origin of HH204 appears to be associated with one of the most brilliant and star formation rich zones of the Orion Nebula, the regions called Orion South, although there are many interactions of gas which appear to feed it from several directions”, adds William Henney, a researcher at the Institute of Radioastronomy and Astrophysics at the The National Autonomous University of Mexico [Universidad Nacional Autónoma de México](MX), and a co-author of the article.

    “Thanks to the images of the Hubble Space Telescope we have shown that HH204 is propagating at an angle of 32º with the plane of the sky, which lets us observe the compression of the gas transversely as we approach the shock front”, points out Karla Arellano Córdova, a researcher at The University of Texas-Austin (US), and a co-author of the article.

    “We have seen that the impact of these objects can be important when determining the local physical conditions in ionized nebulae. In fact, if we don’t take these effects into account we can make incorrect determinations of the chemical composition of the ionized nebulae, which are fundamental techniques for understanding the chemical evolution of the Universe”, sums up Jorge García Rojas, an IAC researcher and a co-author of the article.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft)

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 8:01 am on August 19, 2021 Permalink | Reply
    Tags: , IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES), , This research opens up a new window for exploring the elusive magnetic fields of the solar chromosphere in the present new era of large-aperture solar telescopes.   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “IRSOL and IAC scientists solve a complex paradox in solar physics” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    18/08/2021

    1
    Image of the solar atmosphere showing a coronal mass ejection. Credit: National Aeronautics Space Agency (US)/SDO.

    In 1998, the journal Nature published a seminal letter concluding that the mysterious polarization signal that had been recently discovered in the light emitted by the sodium atoms of the solar atmosphere implies that the solar chromosphere (a very important layer of the solar atmosphere) is practically unmagnetized, in sharp contradiction with common wisdom. This paradox motivated laboratory experiments and theoretical investigations, which instead of providing a solution, raised new issues and even led some scientists to question the quantum theory of radiation-matter interaction. In an article published and highlighted today by the prestigious Physical Review Letters, Ernest Alsina Ballester (IRSOL and IAC), Luca Belluzzi (IRSOL) and Javier Trujillo Bueno (IAC) show the solution to such intriguing paradox, which has puzzled solar physicists over the last decades. This research opens up a new window for exploring the elusive magnetic fields of the solar chromosphere in the present new era of large-aperture solar telescopes.

    Twenty-five years ago, an enigmatic signal was discovered while analyzing the polarization of sunlight with a new instrument, the Zurich Imaging Polarimeter (ZIMPOL) [Nature]. This mysterious linear polarization signal appears at the 5896 Å wavelength of the D1 line of neutral sodium where, according to the line’s quantum numbers, no linear polarization due to scattering processes should be present. This polarization signal was therefore totally unexpected, and its interpretation immediately opened an intense scientific debate. The mystery further increased two years later, when the journal Nature published a letter with an explanation, which required that the sublevels of the lower level of the D1 line are not equally populated. In that theoretical work, the enigmatic polarization signal of the D1 line was reproduced remarkably well. However, the proposed explanation implied that the region of the solar atmosphere known as the chromosphere is completely unmagnetized, in apparent contradiction with established results, which instead indicate that the quiet regions (outside sunspots) of the solar chromosphere are permeated by magnetic fields in the gauss range. This opened a serious paradox, which has challenged solar physicists for many years, and even led some scientists to question the quantum theory of atom-photon interactions.

    A first breakthrough towards the resolution of the paradox was achieved in 2013 at the IAC, when Luca Belluzzi and Javier Trujillo Bueno theoretically discovered a new mechanism through which linear polarization can be produced in the sodium D1 line without the need of population imbalances in the lower level of the D1 line. However, that important step given by these researchers was for the idealized case of a solar atmosphere model without magnetic fields.

    1
    Figure 1: Variation with wavelength of the linear polarization (Q/I) of sunlight across the solar sodium D1 and D2 spectral lines (left panel) and across D1 (right panel). The black curves indicate the observed signals (the measurements were carried out at IRSOL with the ZIMPOL instrument). The red and blue curves show the results of theoretical calculations carried out neglecting (red) and including (blue) magnetic fields. An excellent agreement between the observation and the theoretical modeling is obtained when assuming that the quiet regions (outside sunspots) of the solar chromosphere are permeated by a magnetic field of 15 gauss.

    In an article published today by Physical Review Letters, the prestigious scientific journal of the American Physical Society, Ernest Alsina Ballester, Luca Belluzzi, and Javier Trujillo Bueno show the solution to this intriguing paradox, which has puzzled solar physicists since 1998. As shown in figure 1, this team of researchers has been able to reproduce the enigmatic observations of the D1 line polarization, in the presence of magnetic fields in the gauss range. To achieve this result, it was necessary to carry out the most complete theoretical modeling of this polarization signal ever attempted, accounting for the joint action of very complex physical mechanisms. This required three years of work, carried out through a close cooperation between the Istituto Ricerche Solari (IRSOL) in Locarno-Monti (affiliated to the Università della Svizzera italiana) and the POLMAG group of the Instituto de Astrofísica de Canarias (IAC) in Tenerife (see http://research.iac.es/proyecto/polmag/).

    This result has very important consequences. Linear polarization signals, like the one observed in the D1 line of sodium, are extremely interesting because they encode unique information on the elusive magnetic fields present in the solar chromosphere. This key interface layer of the solar atmosphere, located between the underlying cooler photosphere and the overlying million-degree corona, is at the core of several enduring problems in solar physics, including the understanding and prediction of the eruptive phenomena that may strongly impact our technology-dependent society. The magnetic field is known to be the main driver of the spectacular dynamical activity of the solar chromosphere, but our empirical knowledge of its intensity and geometry is still largely unsatisfactory. The solution of the long-standing paradox of solar D1 line polarization proves the validity of the present quantum theory of spectral line polarization, and opens up a new window to explore the magnetism of the solar atmosphere in the present new era of large-aperture solar telescopes.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft)

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    [caption id="attachment_72536" align="alignnone" width="632"] Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 9:54 pm on August 18, 2021 Permalink | Reply
    Tags: "A nonlinear damping mechanism for waves in the solar corona", IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES),   

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) : “A nonlinear damping mechanism for waves in the solar corona” 

    Instituto de Astrofísica de Andalucía

    From IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES)

    17/08/2021

    1
    Scatter plot of oscillation amplitude and damping ratio values for 101 loop oscillation cases. The symbols and their colors indicate the levels of evidence obtained for the nonlinear (NL) and the linear resonant absorption (RA) models.

    The solar coronal heating problem originated almost 80 years ago and remains unsolved. A plausible explanation lies in mechanisms based on magnetic wave energy dissipation. Currently, several linear and nonlinear wave damping models have been proposed. The advent of space instrumentation has led to the creation of catalogues containing the properties of a large number of loop oscillation events. When the damping ratio of the oscillations is plotted against their oscillation amplitude, the data are scattered forming a cloud with a triangular shape. Larger amplitudes correspond in general to smaller damping ratio values and vice versa. Here, a Bayesian model comparison analysis has quantified the evidence for a nonlinear damping model relative to the evidence for linear resonant absorption in explaining the observed damping of coronal loop oscillations. The results indicate that there is qualitative agreement between the regions of high marginal likelihood and Bayes factor for the nonlinear damping model and the arrangement of observed data. A quantitative application to 101 loop oscillation cases observed with the Solar Dynamics Observatory (SDO, NASA) results in the marginal likelihood for the nonlinear model being larger in the majority of them. Moreover, the cases with conclusive evidence for the nonlinear model outnumber considerably those in favor of linear resonant absorption. Nonlinear damping is therefore a plausible explanation for the observed damping of solar coronal waves.

    Science paper:
    The Astrophysical Journal Letters

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft)

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009, the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    [caption id="attachment_72536" align="alignnone" width="632"] Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
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