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6 results on '"Schmidt B.P."'

1. Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way

Author

Howes, L.M., Casey, A.R., Asplund, M., Keller, S.C., Yong, D., Nataf, D.M., Poleski, R., Lind, K., Kobayashi, C., Owen, C.I., Ness, M., Bessell, M.S., Da Costa, G.S., Schmidt, B.P., Tisserand, P., Udalski, A., Szymanski, M.K., Soszynski, I., Pietrzynski, G., Ulaczyk, K., Wyrzykowski, L., Pietrukowicz, P., Skowron, J., Kozlowski, S., and Mroz, P.

Subjects
Milky Way -- Observations, Galaxies -- Observations, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

The first stars are predicted to have formed within 200 million years after the Big Bang (1), initiating the cosmic dawn. A true first star has not yet been discovered, [...]

Published
2015

2. A single low-energy, iron-poor supernova as the source of metals in the star SMSS J031300.36-670839.3

Author

Keller, S.C., Bessell, M.S., Frebel, A., Casey, A.R., Asplund, M., Jacobson, H.R., Lind, K., Norris, J.E., Yong, D., Heger, A., Magic, Z., Costa, G.S. Da, Schmidt, B.P., and Tisserand, P.

Subjects
Supernovae -- Observations -- Chemical properties -- Natural history, Astronomical research, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

The element abundance ratios of four low-mass stars with extremely low metallicities (abundances of elements heavier than helium) indicate that the gas out of which the stars formed was enriched in each case by at most a few- and potentially only one--low-energy supernova (1-4). Such supernovae yield large quantities of light elements such as carbon but very little iron. The dominance of low-energy supernovae seems surprising, because it had been expected that the first stars were extremely massive, and that they disintegrated in pair-instability explosions that would rapidly enrich galaxies in iron (5). What has remained unclear is the yield of iron from the first supernovae, because hitherto no star has been unambiguously interpreted as encapsulating the yield of a single supernova. Here we report the optical spectrum of SMSS J031300.36-670839.3, which shows no evidence of iron (with an upper limit of [10.sup.-7.1] times solar abundance). Based on a comparison of its abundance pattern with those of models, we conclude that the star was seeded with material from a single supernova with an original mass about 60 times that of the Sun (and that the supernova left behind a black hole). Taken together with the four previously mentioned low-metallicity stars, we conclude that low-energy supernovae were common in the early Universe, and that such supernovae yielded light-element enrichment with insignificant iron. Reduced stellar feedback both chemically and mechanically from low-energy supernovae would have enabled first-generation stars to form over an extended period. We speculate that such stars may perhaps have had an important role in the epoch of cosmic reionization and the chemical evolution of early galaxies., Whereas the solar spectrum contains many thousands of spectral lines due to iron and other elements, the high-resolution (R = 28,000) optical spectrum of SMSS J031300.36-670839.3 (hereafter SMSS 0313 - [...]

Published
2014

3. A photometric redshift of z = 6.39 ± 0.12 for GRB 050904

Author

Ivarsen, K.M., Levan, A., Fernandez, A.J.M., Barthelmy, S., MacLeod, C.L., Hartmann, D.H., Canterna, R., Moon, D.S., Bayliss, M.B., Tanvir, N., Gorosabel, J., Zdarowicz, C.M., Lamb, D.Q., Kulkarni, S.R., Fruchter, A.S., Gehrels, N., Moles, M., Hudec, R., Alvarez, A., Bartelme, J.W., Guziy, S., Kirschbrown, J.R., Evans, C.R., Castro-Tirado, A.J., Price, P.A., Rol, E., Williams, G.G., Prada, F., Bersier, D., Chapman, R., Alfaro, E., Crain, J.A., Priddey, R., Reichart, D.E., Rhoads, J., Mack, C.E., Kasliwal, M.M., Clemens, J.C., De Ugarte Postigo, A., Foster, A.C., Jelinek, M., Park, H.-S., Maturana, D., Burrows, D.N., O'Brien, P., Soderberg, A.M., Kubanek, P., Graham, J., LaCluyze, A., Kumar, N.D., Ugarte, P., Gal-Yam, A., Cenko, S.B., Haislip, J.B., Klose, S., Henden, A.A., Vitek, S., Pizarro, S., Jarvis, M.J., Schmidt, B.P., Fox, D.B., Nysewander, M.C., Wijers, R.A.M.J., Figueredo, E., Cypriano, E.S., Kouveliotou, C., and Harrison, F.A.

Abstract

Gamma-ray bursts (GRBs) and their afterglows are the most brilliant transient events in the Universe. Both the bursts themselves and their afterglows have been predicted to be visible out to redshifts of z ≈ 20, and therefore to be powerful probes of the early Universe1,2. The burst GRB 000131, at z = 4.50, was hitherto the most distant such event identified3. Here we report the discovery of the bright near-infrared afterglow of GRB 050904 (ref. 4). From our measurements of the near-infrared afterglow, and our failure to detect the optical afterglow, we determine the photometric redshift of the burst to be z = 6.39-0.12+0.11 (refs 5-7). Subsequently, it was measured8 spectroscopically to be z = 6.29 ± 0.01, in agreement with our photometric estimate. These results demonstrate that GRBs can be used to trace the star formation, metallicity, and reionization histories of the early Universe.

Published
2006
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4. The unusually long duration gamma-ray burst GRB 000911: Discovery of the afterglow and host galaxy

Author

Cline, T., Hurley, K., Mahabal, A., Mazets, E., Frail, D.A., Berger, E., Schmidt, B.P., Golenetskii, S., Djorgovski, S.G., Morrison, G., Reichart, D.E., Trombka, J., Bloom, J.S., Harrison, F.A., Sari, R., Price, P.A., Yost, S.A., Galama, T.J., Axelrod, T.S., Kulkarni, S.R., and Fox, D.W.

Abstract

Of all the well-localized gamma-ray bursts, GRB 000911 has the longest duration (T90 = 500 s) and ranks in the top 1% of BATSE bursts for fluence. Here we report the discovery of the afterglow of this unique burst. In order to simultaneously fit our radio and optical observations, we are required to invoke a model involving a hard electron distribution, p ∼ 1.5, and a jet-break time less than 1.5 days. A spectrum of the host galaxy taken 111 days after the burst reveals a single emission line, interpreted as [011] at a redshift z = 1.0585, and a continuum break that we interpret as the Balmer limit at this redshift. Despite the long 790, the afterglow of GRB 000911 is not unusual in any other way when compared to the set of afterglows studied to date. We conclude that the duration of the GRB plays little part in determining the physics of the afterglow.

Published
2002
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6. The Gaia-ESO Survey: the most metal-poor stars in the Galactic bulge

Author

Alejandra Recio-Blanco, David M. Nataf, Sofia Randich, Karin Lind, A. Hourihane, Carmela Lardo, Sofia Feltzing, G. G. Sacco, Martin Asplund, C. C. Worley, Paula Jofre, Andreas Korn, David Yong, C. Allende Prieto, L. M. Howes, G. S. Da Costa, Enrico Maiorca, Manuela Zoccali, Francesco Damiani, L. Morbidelli, Vanessa Hill, Maria Bergemann, Ulrike Heiter, Andrew R. Casey, Rodolfo Smiljanic, Gerard Gilmore, Stefan Keller, Michael S. Bessell, Dante Minniti, Patrick Tisserand, Laura Magrini, Anna F. Marino, Brian P. Schmidt, Antonella Vallenari, Thomas Masseron, Luca Casagrande, Ettore Flaccomio, P. de Laverny, Elena Pancino, Thomas Bensby, Christopher Owen, M. T. Costado, Howes L.M., Asplund M., Casey A.R., Keller S.C., Yong D., Gilmore G., Lind K., Worley C., Bessell M.S., Casagrande L., Marino A.F., Nataf D.M., Owen C.I., Da Costa G.S., Schmidt B.P., Tisserand P., Randich S., Feltzing S., Vallenari A., Allende Prieto C., Bensby T., Flaccomio E., Korn A.J., Pancino E., Recio-Blanco A., Smiljanic R., Bergemann M., Costado M.T., Damiani F., Heiter U., Hill V., Hourihane A., Jofre P., Lardo C., de Laverny P., Magrini L., Maiorca E., Masseron T., Morbidelli L., Sacco G.G., Minniti D., and Zoccali M.

Subjects
010504 meteorology & atmospheric sciences, Evolution, Metallicity, K-type main-sequence star, Milky Way, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Bulge, 0103 physical sciences, Galaxy formation and evolution, Population II-Galaxy, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, Spiral galaxy, Bulge-Galaxy, Astronomy, Astronomy and Astrophysics, Stars, Astrophysics - Astrophysics of Galaxies, Galaxy, Abundances-star, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics
Abstract

We present the first results of the EMBLA survey (Extremely Metal-poor BuLge stars with AAOmega), aimed at finding metal-poor stars in the Milky Way bulge, where the oldest stars should now preferentially reside. EMBLA utilises SkyMapper photometry to pre-select metal-poor candidates, which are subsequently confirmed using AAOmega spectroscopy. We describe the discovery and analysis of four bulge giants with -2.72, Comment: 7 pages, 5 figures. Accepted for publication by MNRAS

Published
2014
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