The intense radiation from a gamma-ray burst (GRB) is shown to be capable of
melting stony material at distances up to 300 light years which subsequently
cool to form chondrules. These conditions were created in the laboratory for
the first time when millimeter sized pellets were placed in a vacuum chamber in
the white synchrotron beam at the European Synchrotron Radiation Facility
(ESRF). The pellets were rapidly heated in the X-ray and gamma-ray furnace to
above 1400 C melted and cooled. This process heats from the inside unlike
normal furnaces. The melted spherical samples were examined with a range of
techniques and found to have microstructural properties similar to the
chondrules that come from meteorites. This experiment demonstrates that GRBs
can melt precursor material to form chondrules that may subsequently influence
the formation of planets. This work extends the field of laboratory
astrophysics to include high power synchrotron sources.Comment: 8 pages, 10 figures. Proceedings of the 5th INTEGRAL Workshop, Munich
  16-20 February 2004. High resolution figures available at
  http://bermuda.ucd.ie/%7Esmcbreen/papers/duggan_01.pd

Carr, A. J.

Duggan, P.

French, J.

Hanlon, L.

McBreen, B.

McBreen, S.

Metcalfe, L.

Winston, E.

English

arXiv

Thein tenseradiation from a Gamma-Ray Burst (GRB) is capable

of melting stony material at distances up to 300 light years which subsequently cool to form chondrules. These conditions were created in the laboratory for the first

time when millimeter sized pellets were placed in a vacuum chamber in the White synchrotron beam at the European Synchrotron Radiation Facility (ESRF). The pellets were rapidly heated in the X-ray and gamma-ray furnace to above 1400◦C melted and cooled. This process heats from the inside unlike normal furnaces. The melted spherical samples were examined with a range of techniques and found to

have microstructural properties similar to the chondrules that come from meteorites. This experiment demonstrates that GRBs can melt precursor material to form chondrules

that may subsequently influence the formation of planets. This work extends the field of laboratory astrophysics to includehigh-p ower synchrotron sources

Scientific Open-access Literature Archive and Repository

DOI 10.1393/ncc/i2005-10121-6IL NUOVO CIMENTO Vol. 28 C, N. 4-5 Luglio-Ottobre 2005Gamma-ray Bursts and X-ray melting of material as a source ofchondrules and planets(∗)E. Winston(1), S. McBreen(2), A. J. Carr(3), B. McBreen(1), P. Duggan(3)L. Hanlon(1), J. French(1) and L. Metcalfe(4)(1) Department of Experimental Physics, University College - Dublin 4, Ireland(2) Astrophysics Missions Division, RSSD of ESA, ESTEC - Noordwijk The Netherlands(3) Department of Mechanical Engineering, University College - Dublin 4, Ireland(4) XMM-Newton Science Operations Center, ESA - Villafranca del Castillo, 28080,Madrid, Spain(ricevuto il 23 Maggio 2005; pubblicato online il 21 Settembre 2005)Summary. — The intense radiation from a Gamma-Ray Burst (GRB) is capableof melting stony material at distances up to 300 light years which subsequently coolto form chondrules. These conditions were created in the laboratory for the firsttime when millimeter sized pellets were placed in a vacuum chamber in the whitesynchrotron beam at the European Synchrotron Radiation Facility (ESRF). Thepellets were rapidly heated in the X-ray and gamma-ray furnace to above 1400 ◦Cmelted and cooled. This process heats from the inside unlike normal furnaces. Themelted spherical samples were examined with a range of techniques and found tohave microstructural properties similar to the chondrules that come from meteorites.This experiment demonstrates that GRBs can melt precursor material to form chon-drules that may subsequently influence the formation of planets. This work extendsthe field of laboratory astrophysics to include high-power synchrotron sources.PACS 98.70.Rz – γ-ray sources: γ-ray bursts.PACS 96.50.Mt – Meteorites micrometeorites and tektites.PACS 97.82.Jw – Infrared excess; debris disks: protoplanetary disks; exo-zodiacaldust.PACS 07.20.Hy – Furnaces; heaters.PACS 01.30.Cc – Conference proceedings.1. – IntroductionChondrules are millimetre sized, spherical objects that constitute the major com-ponent of chondrite meteorites that originate in the region between Mars and Jupiterand which fall to Earth. The meteorites are the debris from a collision that destroyeda planet. The composition of the meteorites contain information on the material thatformed the planet and hence chondrules are considered to be an important stage in the(∗) Paper presented at the “4th Workshop on Gamma-Ray Burst in the Afterglow Era”, Rome,October 18-22, 2004.c© Societa` Italiana di Fisica 653654 E. WINSTON, S. MCBREEN, A. J. CARR ETC.b)Fig. 1. – Backscattered electron microscope images of (a) a chondrule from the Allende meteoriteand (b) a melted sample from the synchrotron run with randomly oriented olivene crystals andType 1A precursor composition. Phases with higher atomic number are brighter in color. Thedark grey grains are elongated olivine crystals in (a) and the brighter regions are the interstitialglassy material.processes leading to the formation of planets. Many proposals [11] have been made for thetransient heat source that melted the precursor material to form chondrules. The mainprocesses include nebular lightning, shock waves and activities associated with the youngSun. Almost all proposed heat sources are local to the solar nebula. One exception is theproposal [3-6] that the chondrules were flash heated to melting point by a nearby GRBwhen iron in the precursor material efficiently absorbed X-rays and low-energy γ-rays.The distance to the source could be up to 300 light years (∼ 100 pc) for a GRB with anisotropic output of 1046 J [9]. This distance limit was obtained using the minimum valueof 2× 106 J kg−1 required to heat and melt the precursor grains [13] and is equivalent toan enormous energy deposition of 108 Jm−2.The timing, duration and conditions that led to the formation of chondrules in thesolar nebula are poorly understood. The properties and thermal histories of the chon-drules have been inferred from an extensive series of experiments [1]. Their mineralogyis dominated by olivine ((Mg,Fe)2SiO4) and pyroxene ((Mg,Fe)SiO3) both being solidsolutions with a wide range in composition. This diversity is consistent with the melt-ing of heterogeneous solids or dust balls. The chemical composition, crystal structuresand morphologies of chondrules have been used to limit the temperature cycle. Thechondrules were rapidly heated in a few seconds, kept at maximum temperature between1400 ◦C and 2000 ◦C for about ten seconds and cooled at a rate of a few thousand degreesper hour. The temperature cycle can be produced by a GRB and the afterglow [6]. Abackscattered electron microscope image of a barred olivene chondrule from the Allendemeteorite is shown in fig. 1a.2. – Experimental methodIt is now possible to create the astrophysical conditions near a GRB source in thelaboratory due to the development of powerful synchrotrons. The ESRF has a 6GeVsynchrotron capable of generating the required power. A wiggler device was inserted andused to create X-rays in the range 3–200 keV. The 24-pole wiggler has a characteristicenergy of 29 keV at a minimum wiggler gap of 20.3mm. The composition of chondrulesvaries widely and a classification system based on the iron content is often used [11].Type IAB chondrules have low iron content while type IA and type II have increasingamounts of iron. The pellets were made from a mixture of elemental oxides with weightpercentages as given in [4, 5]. The powder was pressed into cylindrical pellets of diam-eter 3mm and height of 3mm. Each pellet was placed in a graphite crucible inside anGAMMA-RAY BURSTS AND X-RAY MELTING OF MATERIAL AS A SOURCE OF ETC. 65520 25 30 35 40 45 50 55 60 65 70 750501001502θCounts per sec.Fig. 2. – X-ray diffraction pattern of a type II sample. The data are plotted with crosses and thecalculated profile is shown as a continuous line. The three sets of vertical bars in the middle ofthe figure are the calculated reflection positions for silicon (top), olivine (middle) and magnetite(bottom). The residuals between the data and the calculated profile are shown at the bottomof the figure indicating a very good match.evacuated container and inserted into the path of the white X-ray beam. The size of thebeam was 2mm× 1.5mm. The synchrotron beam entered the vacuum chamber througha Kapton window of thickness 0.05mm. The pressure in the container was between 10−2and 10−3mbar, which is typical of planetary forming systems. During the heating cyclethe temperature of the pellet was measured using a pyrometer with a range from 1000 ◦Cto 3000 ◦C. The pellets were rapidly heated in the X-ray and γ-ray furnace to tempera-tures above 1400 ◦C. The melted samples were kept at the maximum temperature for aduration of 10 s to 300 s and cooled when the power in the beam was reduced by widen-ing the magnets of the wiggler. The beam was removed when the temperature droppedbelow 1000 ◦C. The samples cooled rapidly to yield 2–3mm diameter black spherules.A Huber model 642 Guinier X-ray powder diffractometer with monochromatic CuKα1radiation was used for powder diffraction. The crystal phases were identified using theJCPDS Powder Diffraction File [4, 5]. Crystal structures were refined using Rietveldanalysis in the range 20◦<2θ<100◦ using Rietica. For angular calibration and quantita-tive phase analysis, a known mass of high-purity silicon (9% to 16% by mass dependingon the sample) was added as an internal standard to the powdered sample.3. – ResultsA total of 24 samples were melted and cooled in the radiation beam. A backscatteredelectron microscope image of one sample is given in fig. 1b.There was a general tendency for the microstructure of the samples to reflect theliquidus temperature [11]. Type IA samples have the highest liquidus temperature of1692 ◦C. The type IA samples were predominantly porphyritic in texture with smallercrystals while IAB were about equal mixture of porphyritic and acicular olivine whereasacicular olivine predominated in type II. The type IA samples had more nuclei through-out the partial melt at the start of cooling on which the crystals could grow [11]. Thegreater number of nucleation sites resulted in more crystals with smaller dimensions.Type II samples had the least number of nucleation sites resulting in fewer but largercrystals. The faster the cooling rate the more imperfect the crystals that formed. Thereis not a perfect match between the microstructure of chondrules (fig. 1a) and the sam-ples produced in the synchrotron beam (fig. 1b). The final texture of samples dependson a range of factors [11] such as the precursor composition, maximum temperature,rate of cooling and duration of heating at maximum temperature. Further experimentsare needed to explore a wider range in parameter space to obtain more observational656 E. WINSTON, S. MCBREEN, A. J. CARR ETC.constraints on the process.The Rietveld plot of one sample is given in fig. 2. The sample in fig. 1b had olivine withweight percentage of 56.6% with the remainder being amorphous while the type II samplehad olivine (86.2 wt-%), magnetite (7.2 wt-%) with the remainder being amorphous. Thestoichiometry of the olivine is Mg1.92Fe0.08SiO4, (i.e. almost pure forsterite) for the typeIA sample (fig. 1b) and Mg1.72Fe0.28SiO4 for the type II sample (fig. 2).4. – DiscussionThis experiment demonstrates that GRBs can melt precursor dust balls to form chon-drules in nearby planetary forming systems. Once formed, the chondrules can movethrough the gas more freely and coagulate to form the building blocks of planets [2].GRBs with durations greater than 2 s are associated with supernovae in massive starsand the formation of Kerr black holes [7,10]. The discovery of more than 100 extra-solargiant planets has opened a range of questions regarding the mechanisms of planetaryformation [12]. The probability that any planetary forming system will be blasted by anearby GRB has been estimated [5,6] to be about 0.1%. In the solar neighbourhood, 7%of stars with high metallicity harbour a planet whereas less than 1% of stars with solarmetallicity seem to have a planet [12]. The high frequency of planetary systems impliesthat more than GRBs are involved and other processes may include nebular lightningand shock waves. However it has recently been shown [8] that a GRB and its post-burstemission can also cause charge separation and lightning storms in a protoplanetary neb-ula. This new process can melt chondrules and significantly increase the probability ofinteraction between GRBs and protoplanetary systems.A GRB can reveal planetary forming systems in other galaxies because there willbe short duration (∼ 1 hour) bursts of infrared radiation from the melting dust whenchondrules form across the whole nebula. These infrared bursts can occur for up toseveral hundred years after the GRB when the expanding shell of radiation melts the dustin planetary forming systems. The faint infrared bursts can be detected with powerfultelescopes such as the Overwhelmingly Large Telescope and the Next Generation SpaceTelescope if the GRB is in a nearby galaxy.REFERENCES[1] Cohen B. A., Hewins R. H. and Yu Y., Nature, 406 (2000) 600.[2] Cuzzi J. N., Hogan R. C., Paque J. M. et al., Astrophys. J., 546 (2001) 496.[3] Duggan P., McBreen B., Hanlon L. et al., in Gamma-ray Bursts in the AfterglowERA, edited by E. Costa, J. Hjorth and F. Frontera (Springer Verlag) 2002, p. 294.[4] Duggan P., McBreen B., Carr A. J. et al., Astron. Astrophys., 409 (2003) L9.[5] Duggan P., McBreen B., Carr A. J. et al., in Proceedings of 5th INTEGRALWorkshop, SP-552, edited by V. Scho¨nfelder, G. Lichti and C. Winkler (BavarianAcademy Sciences) 2003, p. 623.[6] McBreen B. and Hanlon L., Astron. Astrophys., 351 (1999) 759.[7] McBreen S., McBreen B., Hanlon L. and Quilligan F., Astron. Astrophys., 393(2002) L15.[8] McBreen B., Winston E., McBreen S. andHanlon L., Astron. Astrophys., 429 (2005)L41.[9] Piran T., Rev. Mod. Phys., 76 (2005) 1143.[10] Popham R., Woosley S. E. and Fryer C., Astrophys. J., 518 (1999) 356.[11] Rubin A. E., Earth-Science Revs., 50 (2000) 3.[12] Santos N. C., Israelian G., Mayor M. et al., Astron. Astrophys., 398 (2003) 363.[13] Wasson J. T., Meteoritics, 28 (1993) 14.

Gamma-ray Bursts and X-ray melting of material as a source of chondrules and planets

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Gamma-ray bursts and X-ray melting of material as a potential source of chondrules and planets

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