TY  - JOUR
A1  - Muraveva, Tatiana
A1  - Palmer, Max
A1  - Clementini, Gisella
A1  - Luri, Xavier
A1  - Cioni, Maria-Rosa L.
A1  - Moretti, Maria Ida
A1  - Marconi, Marcella
A1  - Ripepi, Vincenzo
A1  - Rubele, Stefano
T1  - New near-infrared period-luminosity-metallicity relations for RR lyrae stars and the outlock for GAIA
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We present results of the analysis of 70 RR Lyrae stars located in the bar of the Large Magellanic Cloud (LMC). Combining the spectroscopically determined metallicity of these stars from the literature with precise periods from the OGLE III catalog and multi-epoch K-s photometry from the VISTA survey of the Magellanic Clouds system, we derive a new near-infrared period-luminosity-metallicity (PLKsZ) relation for RR Lyrae variables. In order to fit the relation we use a fitting method developed specifically for this study. The zero-point of the relation is estimated two different ways: by assuming the value of the distance to the LMC and by using Hubble Space Telescope parallaxes of five RR Lyrae stars in the Milky Way (MW). The difference in distance moduli derived by applying these two approaches is similar to 0.2 mag. To investigate this point further we derive the PL(Ks)Z relation based on 23 MW RR Lyrae stars that had been analyzed in Baade-Wesselink studies. We compared the derived PL(Ks)Z relations for RR Lyrae stars in the MW and LMC. Slopes and zero-points are different, but still consistent within the errors. The shallow slope of the metallicity term is confirmed by both LMC and MW variables. The astrometric space mission Gaia is expected to provide a huge contribution to the determination of the RR Lyrae PL(Ks)Z relation; however, calculating an absolute magnitude from the trigonometric parallax of each star and fitting a PL(Ks)Z relation directly to period and absolute magnitude leads to biased results. We present a tool to achieve an unbiased solution by modeling the data and inferring the slope and zero-point of the relation via statistical methods.
KW  - astrometry
KW  - distance scale
KW  - Magellanic Clouds
KW  - methods: data analysis
KW  - stars: statistics
KW  - stars: variables: RR Lyrae
Y1  - 2015
U6  - https://doi.org/10.1088/0004-637X/807/2/127
SN  - 0004-637X
SN  - 1538-4357
VL  - 807
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Shayduk, Roman
A1  - Hallmann, Jörg
A1  - Rodriguez-Fernandez, Angel
A1  - Scholz, Markus
A1  - Lu, Wei
A1  - Bösenberg, Ulrike
A1  - Möller, Johannes
A1  - Zozulya, Alexey
A1  - Jiang, Man
A1  - Wegner, Ulrike
A1  - Secareanu, Radu-Costin
A1  - Palmer, Guido
A1  - Emons, Moritz
A1  - Lederer, Max
A1  - Volkov, Sergey
A1  - Lindfors-Vrejoiu, Ionela
A1  - Schick, Daniel
A1  - Herzog, Marc
A1  - Bargheer, Matias
A1  - Madsen, Anders
T1  - Femtosecond x-ray diffraction study of multi-THz coherent phonons in SrTiO3
JF  - Applied physics letters
N2  - We report generation of ultra-broadband longitudinal acoustic coherent phonon wavepackets in SrTiO3 (STO) with frequency components extending throughout the first Brillouin zone. The wavepackets are efficiently generated in STO using femtosecond infrared laser excitation of an atomically flat 1.6 nm-thick epitaxial SrRuO3 film. We use femtosecond x-ray diffraction at the European X-Ray Free Electron Laser Facility to study the dispersion and damping of phonon wavepackets. The experimentally determined damping constants for multi-THz frequency phonons compare favorably to the extrapolation of a simple ultrasound damping model over several orders of magnitude.
Y1  - 2022
U6  - https://doi.org/10.1063/5.0083256
SN  - 0003-6951
SN  - 1077-3118
VL  - 120
IS  - 20
PB  - AIP Publishing
CY  - Melville
ER  -