87 research outputs found
Characterizing Exoplanets in the Visible and Infrared: A Spectrometer Concept for the EChO Space Mission
Transit-spectroscopy of exoplanets is one of the key observational techniques
to characterize the extrasolar planet and its atmosphere. The observational
challenges of these measurements require dedicated instrumentation and only the
space environment allows an undisturbed access to earth-like atmospheric
features such as water or carbon-dioxide. Therefore, several exoplanet-specific
space missions are currently being studied. One of them is EChO, the Exoplanet
Characterization Observatory, which is part of ESA's Cosmic Vision 2015-2025
program, and which is one of four candidates for the M3 launch slot in 2024. In
this paper we present the results of our assessment study of the EChO
spectrometer, the only science instrument onboard this spacecraft. The
instrument is a multi-channel all-reflective dispersive spectrometer, covering
the wavelength range from 400 nm to 16 microns simultaneously with a moderately
low spectral resolution. We illustrate how the key technical challenge of the
EChO mission - the high photometric stability - influences the choice of
spectrometer concept and drives fundamentally the instrument design. First
performance evaluations underline the fitness of the elaborated design solution
for the needs of the EChO mission.Comment: 20 pages, 8 figures, accepted for publication in the Journal of
Astronomical Instrumentatio
Measurement of the LT-asymmetry in \pi^0 electroproduction at the energy of the \Delta (1232) resonance
The reaction p(e,e'p)pi^0 has been studied at Q^2=0.2 (GeV/c)^2 in the region
of W=1232 MeV. From measurements left and right of q, cross section asymmetries
\rho_LT have been obtained in forward kinematics \rho_LT(\theta_\pi^0=20deg) =
(-11.68 +/- 2.36_stat +/- 2.36_sys)$ and backward kinematics
\rho_LT(\theta_\pi^0=160deg) =(12.18 +/- 0.27_stat +/- 0.82_sys). Multipole
ratios \Re(S_1+^* M_1+)/|M_1+|^2 and \Re(S_0+^* M_1+)/|M_1+|^2 were determined
in the framework of the MAID2003 model. The results are in agreement with older
data. The unusally strong negative \Re(S_0+^* M_1+)/|M_1+|^2 required to bring
also the result of Kalleicher et al. in accordance with the rest of the data is
almost excluded.Comment: 7 pages, 7 figures, 4 tables. Changed content. Accepted for
publication in EPJ
The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory
The Photodetector Array Camera and Spectrometer (PACS) is one of the three
science instruments on ESA's far infrared and submillimetre observatory. It
employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16x25
pixels, each, and two filled silicon bolometer arrays with 16x32 and 32x64
pixels, respectively, to perform integral-field spectroscopy and imaging
photometry in the 60-210\mu\ m wavelength regime. In photometry mode, it
simultaneously images two bands, 60-85\mu\ m or 85-125\mu\m and 125-210\mu\ m,
over a field of view of ~1.75'x3.5', with close to Nyquist beam sampling in
each band. In spectroscopy mode, it images a field of 47"x47", resolved into
5x5 pixels, with an instantaneous spectral coverage of ~1500km/s and a spectral
resolution of ~175km/s. We summarise the design of the instrument, describe
observing modes, calibration, and data analysis methods, and present our
current assessment of the in-orbit performance of the instrument based on the
Performance Verification tests. PACS is fully operational, and the achieved
performance is close to or better than the pre-launch predictions
Measurement of the beam-helicity asymmetry in the p(e_pol,e'p)pi_0 reaction at the energy of the Delta(1232) resonance
In a p(e_pol,e'p)pi_0 out-of-plane coincidence experiment at the
3-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry
has been precisely measured around the energy of the Delta(1232) resonance and
Q^2 = 0.2 (GeV/c)^2. The results are in disagreement with three up-to-date
model calculations. This is interpreted as lack of understanding of the
non-resonant background, which in dynamical models is related to the pion
cloud.Comment: 5 pages, 2 figures, 2 table
4D treatment planning for scanned ion beams
At Gesellschaft für Schwerionenforschung (GSI) more than 330 patients have been treated with scanned carbon ion beams in a pilot project. To date, only stationary tumors have been treated. In the presence of motion, scanned ion beam therapy is not yet possible because of interplay effects between scanned beam and target motion which can cause severe mis-dosage. We have started a project to treat tumors that are subject to respiratory motion. A prototype beam application system for target tracking with the scanned pencil beam has been developed and commissioned
The CARMENES search for exoplanets around M dwarfs High-resolution optical and near-infrared spectroscopy of 324 survey stars
The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520–1710 nm at a resolution of at least R >80 000, and we measure its RV, Hα emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700–900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m s−1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3–4 m s−1
The CARMENES search for exoplanets around M dwarfs. Two temperate Earth-mass planet candidates around Teegarden’s Star
Context.Teegarden’s Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0 V),the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES.Aims.As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of Teegarden’sStar and analysed them for planetary signals.Methods.We find periodic variability in the radial velocities of Teegarden’s Star. We also studied photometric measurements to rule out stellarbrightness variations mimicking planetary signals.Results.We find evidence for two planet candidates, each with 1.1M⊕minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. Noevidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotationand old age.Conclusions.The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cooldwarf for which the masses have been determined using radial velocities.We thank the referee Rodrigo Díaz for a careful review andhelpful comments. M.Z. acknowledges support from the Deutsche Forschungs-gemeinschaft under DFG RE 1664/12-1 and Research Unit FOR2544 “BluePlanets around Red Stars”, project no. RE 1664/14-1. CARMENES isan instrument for the Centro Astronómico Hispano-Alemán de Calar Alto(CAHA, Almería, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de InvestigacionesCientíficas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut für Astronomie, Instituto de Astrofísica de Andalucía, LandessternwarteKönigstuhl, Institut de Ciències de l’Espai, Institut für Astrophysik Göttingen,Universidad Complutense de Madrid, Thüringer Landessternwarte Tautenburg,Instituto de Astrofísica de Canarias, Hamburger Sternwarte, Centro de Astro-biología and Centro Astronómico Hispano-Alemán), with additional contribu-tions by the Spanish Ministry of Economy, the German Science Foundationthrough the Major Research Instrumentation Programme and DFG ResearchUnit FOR2544 “Blue Planets around Red Stars”, the Klaus Tschira Stiftung, thestates of Baden-Württemberg and Niedersachsen, and by the Junta de Andalucía.Based on data from the CARMENES data archive at CAB (INTA-CSIC). Thisarticle is based on observations made with the MuSCAT2 instrument, devel-oped by ABC, at Telescopio Carlos Sánchez operated on the island of Tener-ife by the IAC in the Spanish Observatorio del Teide. Data were partly col-lected with the 150-cm and 90-cm telescopes at the Sierra Nevada Observa-tory (SNO) operated by the Instituto de Astrofísica de Andalucía (IAA-CSIC).Data were partly obtained with the MONET/South telescope of the MOnitoringNEtwork of Telescopes, funded by the Alfried Krupp von Bohlen und HalbachFoundation, Essen, and operated by the Georg-August-Universität Göttingen,the McDonald Observatory of the University of Texas at Austin, and the SouthAfrican Astronomical Observatory. We acknowledge financial support from theSpanish Agencia Estatal de Investigación of the Ministerio de Ciencia, Inno-vación y Universidades and the European FEDER/ERF funds through projectsAYA2015-69350-C3-2-P, AYA2016-79425-C3-1/2/3-P, AYA2018-84089, BES-2017-080769, BES-2017-082610, ESP2015-65712-C5-5-R, ESP2016-80435-C2-1/2-R, ESP2017-87143-R, ESP2017-87676-2-2, ESP2017-87676-C5-1/2/5-R, FPU15/01476, RYC-2012-09913, the Centre of Excellence ”Severo Ochoa”and ”María de Maeztu” awards to the Instituto de Astrofísica de Canarias (SEV-2015-0548), Instituto de Astrofísica de Andalucía (SEV-2017-0709), and Cen-tro de Astrobiología (MDM-2017-0737), the Generalitat de Catalunya throughCERCA programme”, the Deutsches Zentrum für Luft- und Raumfahrt throughgrants 50OW0204 and 50OO1501, the European Research Council through grant694513, the Italian Ministero dell’instruzione, dell’università de della ricerca andUniversità degli Studi di Roma Tor Vergata through FFABR 2017 and “Mis-sion: Sustainability 2016”, the UK Science and Technology Facilities Council through grant ST/P000592/1, the Israel Science Foundation through grant848/16, the Chilean CONICYT-FONDECYT through grant 3180405, the Mexi-can CONACYT through grant CVU 448248, the JSPS KAKENHI through grantsJP18H01265 and 18H05439, and the JST PRESTO through grant JPMJPR1775
The CARMENES search for exoplanets around M dwarfs HD147379 b: A nearby Neptune in the temperate zone of an early-M dwarf
We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 (V = 8.9 mag, M = 0.58 ± 0.08 M⊙), a bright M0.0 V star at a distance of 10.7 pc, is found to undergo periodic RV variations with a semi-amplitude of K = 5.1 ± 0.4 m s−1 and a period of P = 86.54 ± 0.06 d. The RV signal is found in our CARMENES data, which were taken between 2016 and 2017, and is supported by HIRES/Keck observations that were obtained since 2000. The RV variations are interpreted as resulting from a planet of minimum mass mP sin i = 25 ± 2 M⊕, 1.5 times the mass of Neptune, with an orbital semi-major axis a = 0.32 au and low eccentricity (e < 0.13). HD 147379 b is orbiting inside the temperate zone around the star, where water could exist in liquid form. The RV time-series and various spectroscopic indicators show additional hints of variations at an approximate period of 21.1 d (and its first harmonic), which we attribute to the rotation period of the star.FEDER/ERF FICTS-2011-02 fundsMajor Research Instrumentation Programme
and DFG Research Unit FOR2544 “Blue Planets around Red StarsEuropean Research Council (ERC-279347), Deutsche Forschungsgemeinschaft
(RE 1664/12-1, RE 2694/4-1), Bundesministerium für Bildung
und Forschung (BMBF-05A14MG3, BMBF-05A17MG3), Spanish Ministry
of Economy and Competitiveness (MINECO, grants AYA2015-68012-C2-2-P,
AYA2016-79425-C3-1,2,3-P, AYA2015-69350-C3-2-P, AYA2014-54348-C03-
01, AYA2014-56359-P, AYA2014-54348-C3-2-R, AYA2016-79425-C3-3-P and
2013 Ramòn y Cajal program RYC-2013-14875), Fondo Europeo de Desarrollo
Regional (FEDER, grant ESP2016-80435-C2-1-R, ESP2015-65712-C5-
5-R), Generalitat de Catalunya/CERCA programme, Spanish Ministerio de
Educación, Cultura y Deporte, programa de Formación de Profesorado Universitario
(grant FPU15/01476), Deutsches Zentrum für Luft- und Raumfahrt
(grants 50OW0204 and 50OO1501), Office of Naval Research Global (award
no. N62909-15-1-2011), Mexican CONACyT grant CB-2012-183007
The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems
Stars and planetary system
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