Showing papers by "M. Schultheis published in 2017"
University of Virginia1, Liverpool John Moores University2, Texas Christian University3, University of La Laguna4, Spanish National Research Council5, Johns Hopkins University6, New Mexico State University7, Sternberg Astronomical Institute8, University of Arizona9, Ohio State University10, Pennsylvania State University11, University of Wisconsin-Madison12, Eötvös Loránd University13, University of Toronto14, University of Michigan15, University of Texas at Austin16, Leibniz Institute for Astrophysics Potsdam17, Yale University18, University of Colorado Boulder19, New York University20, Princeton University21, University of Utah22, Goddard Space Flight Center23, Aarhus University24, University of Birmingham25, Harvard University26, Space Telescope Science Institute27, Computer Sciences Corporation28, Paris Diderot University29, INAF30, Max Planck Society31, Space Science Institute32, Pierre-and-Marie-Curie University33, University of Franche-Comté34, Federal University of Rio de Janeiro35, University of Nice Sophia Antipolis36
TL;DR: In this article, the Hungarian National Research, Development and Innovation Office (K-119517) and Hungarian National Science Foundation (KNFI) have proposed a method to detect the presence of asteroids in Earth's magnetic field.
Abstract: National Science Foundation [AST-1109178, AST-1616636]; Gemini Observatory; Spanish Ministry of Economy and Competitiveness [AYA-2011-27754]; NASA [NNX12AE17G]; Hungarian Academy of Sciences; Hungarian NKFI of the Hungarian National Research, Development and Innovation Office [K-119517]; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science
1,193 citations
Liverpool John Moores University1, Spanish National Research Council2, University of La Laguna3, INAF4, University of Franche-Comté5, Max Planck Society6, University of New South Wales7, University of Arizona8, Leibniz Institute for Astrophysics Potsdam9, University of Texas at Austin10, Eötvös Loránd University11, Apache Corporation12, Sternberg Astronomical Institute13, University of Notre Dame14, University of Virginia15, Ohio State University16, Texas Christian University17, Pennsylvania State University18, New Mexico State University19, University of Michigan20, Steward Health Care System21, University of Toronto22, University of Nice Sophia Antipolis23, Johns Hopkins University24
TL;DR: Alfred P. Sloan Foundation, National Science Foundation, US Department of Energy Office of Science, University of Arizona, Brazilian Participation Group, Brookhaven National Laboratory; University of Cambridge; Carnegie Mellon University; University Of Florida; French Participation Group; German Participation Group and Harvard University; Instituto de Astrofisica de Canarias; Michigan State/Notre Dame/JINA Participation Group as discussed by the authors.
Abstract: Alfred P. Sloan Foundation; National Science Foundation; US Department of Energy Office of Science; University of Arizona; Brazilian Participation Group; Brookhaven National Laboratory; University of Cambridge; Carnegie Mellon University; University of Florida; French Participation Group; German Participation Group; Harvard University; Instituto de Astrofisica de Canarias; Michigan State/Notre Dame/JINA Participation Group; Johns Hopkins University; Lawrence Berkeley National Laboratory; Max Planck Institute for Astrophysics; New Mexico State University; New York University; Ohio State University; Pennsylvania State University; University of Portsmouth; Princeton University; Spanish Participation Group; University of Tokyo; University of Utah; Vanderbilt University; University of Virginia; University of Washington; Yale University; Physics Frontier Center/Joint Institute or Nuclear Astrophysics (JINA) [PHY 14-30152]; Physics Frontier Center/JINA Center for the Evolution of the Elements (JINA-CEE) by the US National Science Foundation; US National Science Foundation; Spanish Ministry of Economy and Competitiveness [AYA2010-16717, AYA2013-42781P]; Spanish Ministry of Economy and Competitiveness (MINECO) [AYA2014-56359-P]; Australian Research Council through DECRA Fellowship [DE140100598]; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences; Ramon y Cajal fellowship [RYC-2013-14182]; MINECO [AYA-2014-58082-P]
192 citations
TL;DR: In this article, the first parallax measurements of the primary standard candles of the cosmological distance ladder, that involve astrometry collected by Gaia during the initial 14 months of science operation, are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS).
Abstract: Parallaxes for 331 classical Cepheids, 31 Type II Cepheids and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, that involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity ($PL$), period-Wesenheit ($PW$) relations for classical and Type II Cepheids and infrared $PL$, $PL$-metallicity ($PLZ$) and optical luminosity-metallicity ($M_V$-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. The new relations were computed using multi-band ($V,I,J,K_{\mathrm{s}},W_{1}$) photometry and spectroscopic metal abundances available in the literature, and applying three alternative approaches: (i) by linear least squares fitting the absolute magnitudes inferred from direct transformation of the TGAS parallaxes, (ii) by adopting astrometric-based luminosities, and (iii) using a Bayesian fitting approach. TGAS parallaxes bring a significant added value to the previous Hipparcos estimates. The relations presented in this paper represent first Gaia-calibrated relations and form a "work-in-progress" milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia's Data Release 2 (DR2) in 2018.
105 citations
TL;DR: In this paper, the first parallax measurements of the primary standard candles of the cosmological distance ladder, that involve astrometry collected by Gaia during the initial 14 months of science operation, are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS).
Abstract: Parallaxes for 331 classical Cepheids, 31 Type II Cepheids and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, that involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity ($PL$), period-Wesenheit ($PW$) relations for classical and Type II Cepheids and infrared $PL$, $PL$-metallicity ($PLZ$) and optical luminosity-metallicity ($M_V$-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. The new relations were computed using multi-band ($V,I,J,K_{\mathrm{s}},W_{1}$) photometry and spectroscopic metal abundances available in the literature, and applying three alternative approaches: (i) by linear least squares fitting the absolute magnitudes inferred from direct transformation of the TGAS parallaxes, (ii) by adopting astrometric-based luminosities, and (iii) using a Bayesian fitting approach. TGAS parallaxes bring a significant added value to the previous Hipparcos estimates. The relations presented in this paper represent first Gaia-calibrated relations and form a "work-in-progress" milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia's Data Release 2 (DR2) in 2018.
103 citations
Liverpool John Moores University1, Ohio State University2, Texas Christian University3, Johns Hopkins University4, Eötvös Loránd University5, Spanish National Research Council6, University of La Laguna7, University of Concepción8, University of Notre Dame9, University of Franche-Comté10, University of Virginia11, INAF12, University of New South Wales13, Sternberg Astronomical Institute14, New Mexico State University15, Pontifical Catholic University of Chile16, University of Chile17, University of Antofagasta18, University of La Serena19, University of Nice Sophia Antipolis20
TL;DR: In this paper, chemical abundances obtained by the SDSS-III/Apache Point Observatory Galactic Evolution Experiment for giant stars in five globular clusters located within 2.2 kpc of the Galactic Centre are reported.
Abstract: We report chemical abundances obtained by Sloan Digital Sky Survey (SDSS)-III/Apache Point Observatory Galactic Evolution Experiment for giant stars in five globular clusters located within 2.2 kpc of the Galactic Centre. We detect the presence of multiple stellar populations in four of those clusters (NGC 6553, NGC 6528, Terzan 5 and Palomar 6) and find strong evidence for their presence in NGC 6522. All clusters with a large enough sample present a significant spread in the abundances of N, C, Na and Al, with the usual correlations and anticorrelations between various abundances seen in other globular clusters. Our results provide important quantitative constraints on theoretical models for self-enrichment of globular clusters, by testing their predictions for the dependence of yields of elements such as Na, N, C and Al on metallicity. They also confirm that, under the assumption that field N-rich stars originate from globular cluster destruction, they can be used as tracers of their parental systems in the high-metallicity regime.
86 citations
TL;DR: In this paper, the authors used the APOGEE stars to derive their metallicity distribution function (MDF) and individual abundances, for α$- and iron-peak elements of the ASPCAP pipeline (DR13), as well as the age distribution for stars in Baade's window (BW).
Abstract: Baade's window (BW) is one of the most observed Galactic bulge fields in terms of chemical abundances. Due to its low and homogeneous interstellar absorption it is considered as a calibration field for Galactic bulge studies. In the era of large spectroscopic surveys, calibration fields such as BW are necessary to cross calibrate the stellar parameters and individual abundances of the APOGEE survey. We use the APOGEE BW stars to derive their metallicity distribution function (MDF) and individual abundances, for $\alpha$- and iron-peak elements of the APOGEE ASPCAP pipeline (DR13), as well as the age distribution for stars in BW. We determine the MDF of APOGEE stars in BW and find a remarkable agreement with that of the Gaia-ESO survey (GES). Both exhibit a clear bimodal distribution. We also find that the Mg-metallicity planes of both surveys agree well, except for the metal-rich part ([Fe/H] >0.1), where APOGEE finds systematically higher Mg abundances with respect to the GES. The ages based on the [C/N] ratio reveal a bimodal age distribution, with a major old population at 10 Gyr, with a decreasing tail towards younger stars. A comparison between APOGEE estimates and stellar parameters, and those determined by other sources reveals detectable systematic offsets, in particular for spectroscopic surface gravity estimates. In general, we find a good agreement between individual abundances of O, Na, Mg, Al, Si, K, Ca, Cr, Mn, Co, and Ni from APOGEE with that of literature values. We have shown that in general APOGEE data show a good agreement in terms of MDF and individual chemical abundances with respect to literature works. Using the [C/N] ration we found a significant fraction of young stars in BW which is in agreement with the model of Haywood et al. (2016).
76 citations
National Autonomous University of Mexico1, Spanish National Research Council2, University of La Laguna3, University of Nice Sophia Antipolis4, University of Notre Dame5, University of Franche-Comté6, Andrés Bello National University7, Universidade Federal do Rio Grande do Sul8, Leibniz Institute for Astrophysics Potsdam9
TL;DR: In this article, the authors examined the variation of chemical abundances in distant halo stars observed by the Apache Point Galactic Evolution Experiment (APOGEE), as a function of distance from the Galactic center and iron abundance.
Abstract: The galaxy formation process in the $\Lambda$-Cold Dark Matter scenario can be constrained from the analysis of stars in the Milky Way's halo system. We examine the variation of chemical abundances in distant halo stars observed by the Apache Point Galactic Evolution Experiment (APOGEE), as a function of distance from the Galactic center ($r$) and iron abundance ([M/H]), in the range 5 $\lesssim r \lesssim$ 30 kpc and $-2.5 15$ kpc and [M/H] $> -1.1$ (larger in the case of O, Mg and S) with respect to the nearest halo stars. This result confirms previous claims for low-$\alpha$ stars found at larger distances. Chemical differences in elements with other nucleosynthetic origins (Ni, K, Na, and Al) are also detected. C and N do not provide reliable information about the interstellar medium from which stars formed because our sample comprises RGB and AGB stars and can experience mixing of material to their surfaces.
43 citations
Posted Content•
TL;DR: In this paper, the first 14 months of the Gaia mission were analyzed using G-band photometry results of 28 days of Ecliptic Pole Scanning Law and 13 months of nominal scanning law.
Abstract: The ESA Gaia mission provides a unique time-domain survey for more than one billion sources brighter than G=20.7 mag. Gaia offers the unprecedented opportunity to study variability phenomena in the Universe thanks to multi-epoch G-magnitude photometry in addition to astrometry, blue and red spectro-photometry, and spectroscopy. Within the Gaia Consortium, Coordination Unit 7 has the responsibility to detect variable objects, classify them, derive characteristic parameters for specific variability classes, and provide global descriptions of variable phenomena.
We describe the variability processing and analysis that we plan to apply to the successive data releases, and we present its application to the G-band photometry results of the first 14 months of Gaia operations that comprises 28 days of Ecliptic Pole Scanning Law and 13 months of Nominal Scanning Law.
Out of the 694 million, all-sky, sources that have calibrated G-band photometry in this first stage of the mission, about 2.3 million sources that have at least 20 observations are located within 38 degrees from the South Ecliptic Pole. We detect about 14% of them as variable candidates, among which the automated classification identified 9347 Cepheid and RR Lyrae candidates. Additional visual inspections and selection criteria led to the publication of 3194 Cepheid and RR Lyrae stars, described in Clementini et al. (2016). Under the restrictive conditions for DR1, the completenesses of Cepheids and RR Lyrae stars are estimated at 67% and 58%, respectively, numbers that will significantly increase with subsequent Gaia data releases.
Data processing within the Gaia Consortium is iterative, the quality of the data and the results being improved at each iteration. The results presented in this article show a glimpse of the exceptional harvest that is to be expected from the Gaia mission for variability phenomena. [abridged]
23 citations
7 citations
01 Jul 2017
TL;DR: In this paper, the authors investigate the effect of the selection function on the metallicity distribution function (MDF) as well as on the vertical metalicity gradient by studying similar lines-of-sight using four different spectroscopic surveys (APOGEE, LAMOST, RAVE and Gaia-ESO).
Abstract: We investigate here the effect of the selection function on the metallicity distribution function (MDF) as well as on the vertical metallicity gradient by studying similar lines-of-sight using four different spectroscopic surveys (APOGEE, LAMOST, RAVE and Gaia-ESO) which have different targeting strategies and therefore different selection functions. We create mock fields for each survey using two stellar population synthesis models, GALAXIA and TRILEGAL. The effects of the selection function are studied in detail by applying the selection function to the two models and comparing the MDF as well as vertical metallicity gradients of the selected sources with that of the underlying sample. We find a negligible selection function effect on the MDF as well as on the vertical metallicity gradients for APOGEE, RAVE and LAMOST, and estimate a mean vertical metallicity gradient of -0.241±0.028 dex kpc−1.
01 Jul 2017
TL;DR: In this article, the authors explore morphological, kinematic and chemical trends of boxy/peanut (b/p) bulges of Milky Way (MW)-type galaxies, to better understand the formation history of the MW’s bulge.
Abstract: Abstract We explore morphological, kinematic and chemical trends of boxy/peanut (b/p) bulges of Milky Way (MW)-type galaxies, to better understand the formation history of the MW’s bulge. We show, using N-body simulations with both a kinematically cold and a kinematically hot disc, that colder populations develop a more prominent bar and X-shaped peanut as compared to their hotter counterpart. Colder discs also exhibit lower line-of-sight velocities (when viewed edge-on) at the edges of the b/p compared to hot discs, in agreement with what is seen for the MW bulge. Furthermore, we explore an N-body model which has three co-spatial discs with metallicities which correspond to the stellar populations of the inner Milky Way, where the α-enhanced thick disc populations are massive and centrally concentrated. The metallicity trends seen in observations of the Bulge can be reproduced in the model without the need of adding any additional components, which hints to the disc origin of the MW’s bulge.