Tachoastrometry: Astrometry with radial velocities

L. Pasquini, C. Cortés, M. Lombardi, L. Monaco, I. C. Leão, B. Delabre

Resultado de la investigación: Article

Resumen

Context. Spectra of composite systems (e.g., spectroscopic binaries) contain spatial information that can be retrieved by measuring the radial velocities (i.e., Doppler shifts) of the components in four observations with the slit rotated by 90 degrees in the sky. Aims. We aim at developing a framework to describe the method and to test its capabilities in a real case. Methods. By using basic concepts of slit spectroscopy we show that the geometry of composite systems can be reliably retrieved by measuring only radial velocity differences taken with different slit angles. The spatial resolution is determined by the precision with which differential radial velocities can be measured. Results. We use the UVES spectrograph at the VLT to observe the known spectroscopic binary star HD 188088 (HIP 97944), which has a maximum expected separation of 23 milli-Arcseconds. We measure an astrometric signal in radial velocity of 276 ms-1, which corresponds to a separation between the two components at the time of the observations of 18 ± 2 milli-Arcseconds. The stars were aligned east-west.We describe a simple optical device to simultaneously record pairs of spectra rotated by 180 degrees, thus reducing systematic effects. We compute and provide the function expressing the shift of the centroid of a seeing-limited image in the presence of a narrow slit. Conclusions. The proposed technique is simple to use and our test shows that it is amenable for deriving astrometry with milliarcsecond accuracy or better, beyond the diffraction limit of the telescope. The technique can be further improved by using simple devices to simultaneously record the spectra with 180 degrees angles. This device together with an optimized data analysis will further reduce the measurement errors. With tachoastrometry, radial velocities and astrometric positions can be measured simultaneously for many double line system binaries in an easy way. The method is not limited to binary stars, but can be applied to any astrophysical configuration in which spectral lines are generated by separate (non-rotational symmetric) regions.

Idioma originalEnglish
Número de artículo24882
PublicaciónAstronomy and Astrophysics
Volumen574
DOI
EstadoPublished - 2015

Huella dactilar

astrometry
radial velocity
slits
binary stars
hot isostatic pressing
composite materials
shift
centroids
diffraction
spectrographs
line spectra
sky
astrophysics
spatial resolution
spectroscopy
telescopes
geometry
stars
configurations
method

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Citar esto

Pasquini, L., Cortés, C., Lombardi, M., Monaco, L., Leão, I. C., & Delabre, B. (2015). Tachoastrometry: Astrometry with radial velocities. Astronomy and Astrophysics, 574, [24882]. https://doi.org/10.1051/0004-6361/201424882
Pasquini, L. ; Cortés, C. ; Lombardi, M. ; Monaco, L. ; Leão, I. C. ; Delabre, B. / Tachoastrometry : Astrometry with radial velocities. En: Astronomy and Astrophysics. 2015 ; Vol. 574.
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title = "Tachoastrometry: Astrometry with radial velocities",
abstract = "Context. Spectra of composite systems (e.g., spectroscopic binaries) contain spatial information that can be retrieved by measuring the radial velocities (i.e., Doppler shifts) of the components in four observations with the slit rotated by 90 degrees in the sky. Aims. We aim at developing a framework to describe the method and to test its capabilities in a real case. Methods. By using basic concepts of slit spectroscopy we show that the geometry of composite systems can be reliably retrieved by measuring only radial velocity differences taken with different slit angles. The spatial resolution is determined by the precision with which differential radial velocities can be measured. Results. We use the UVES spectrograph at the VLT to observe the known spectroscopic binary star HD 188088 (HIP 97944), which has a maximum expected separation of 23 milli-Arcseconds. We measure an astrometric signal in radial velocity of 276 ms-1, which corresponds to a separation between the two components at the time of the observations of 18 ± 2 milli-Arcseconds. The stars were aligned east-west.We describe a simple optical device to simultaneously record pairs of spectra rotated by 180 degrees, thus reducing systematic effects. We compute and provide the function expressing the shift of the centroid of a seeing-limited image in the presence of a narrow slit. Conclusions. The proposed technique is simple to use and our test shows that it is amenable for deriving astrometry with milliarcsecond accuracy or better, beyond the diffraction limit of the telescope. The technique can be further improved by using simple devices to simultaneously record the spectra with 180 degrees angles. This device together with an optimized data analysis will further reduce the measurement errors. With tachoastrometry, radial velocities and astrometric positions can be measured simultaneously for many double line system binaries in an easy way. The method is not limited to binary stars, but can be applied to any astrophysical configuration in which spectral lines are generated by separate (non-rotational symmetric) regions.",
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author = "L. Pasquini and C. Cort{\'e}s and M. Lombardi and L. Monaco and Le{\~a}o, {I. C.} and B. Delabre",
year = "2015",
doi = "10.1051/0004-6361/201424882",
language = "English",
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Pasquini, L, Cortés, C, Lombardi, M, Monaco, L, Leão, IC & Delabre, B 2015, 'Tachoastrometry: Astrometry with radial velocities', Astronomy and Astrophysics, vol. 574, 24882. https://doi.org/10.1051/0004-6361/201424882

Tachoastrometry : Astrometry with radial velocities. / Pasquini, L.; Cortés, C.; Lombardi, M.; Monaco, L.; Leão, I. C.; Delabre, B.

En: Astronomy and Astrophysics, Vol. 574, 24882, 2015.

Resultado de la investigación: Article

TY - JOUR

T1 - Tachoastrometry

T2 - Astrometry with radial velocities

AU - Pasquini, L.

AU - Cortés, C.

AU - Lombardi, M.

AU - Monaco, L.

AU - Leão, I. C.

AU - Delabre, B.

PY - 2015

Y1 - 2015

N2 - Context. Spectra of composite systems (e.g., spectroscopic binaries) contain spatial information that can be retrieved by measuring the radial velocities (i.e., Doppler shifts) of the components in four observations with the slit rotated by 90 degrees in the sky. Aims. We aim at developing a framework to describe the method and to test its capabilities in a real case. Methods. By using basic concepts of slit spectroscopy we show that the geometry of composite systems can be reliably retrieved by measuring only radial velocity differences taken with different slit angles. The spatial resolution is determined by the precision with which differential radial velocities can be measured. Results. We use the UVES spectrograph at the VLT to observe the known spectroscopic binary star HD 188088 (HIP 97944), which has a maximum expected separation of 23 milli-Arcseconds. We measure an astrometric signal in radial velocity of 276 ms-1, which corresponds to a separation between the two components at the time of the observations of 18 ± 2 milli-Arcseconds. The stars were aligned east-west.We describe a simple optical device to simultaneously record pairs of spectra rotated by 180 degrees, thus reducing systematic effects. We compute and provide the function expressing the shift of the centroid of a seeing-limited image in the presence of a narrow slit. Conclusions. The proposed technique is simple to use and our test shows that it is amenable for deriving astrometry with milliarcsecond accuracy or better, beyond the diffraction limit of the telescope. The technique can be further improved by using simple devices to simultaneously record the spectra with 180 degrees angles. This device together with an optimized data analysis will further reduce the measurement errors. With tachoastrometry, radial velocities and astrometric positions can be measured simultaneously for many double line system binaries in an easy way. The method is not limited to binary stars, but can be applied to any astrophysical configuration in which spectral lines are generated by separate (non-rotational symmetric) regions.

AB - Context. Spectra of composite systems (e.g., spectroscopic binaries) contain spatial information that can be retrieved by measuring the radial velocities (i.e., Doppler shifts) of the components in four observations with the slit rotated by 90 degrees in the sky. Aims. We aim at developing a framework to describe the method and to test its capabilities in a real case. Methods. By using basic concepts of slit spectroscopy we show that the geometry of composite systems can be reliably retrieved by measuring only radial velocity differences taken with different slit angles. The spatial resolution is determined by the precision with which differential radial velocities can be measured. Results. We use the UVES spectrograph at the VLT to observe the known spectroscopic binary star HD 188088 (HIP 97944), which has a maximum expected separation of 23 milli-Arcseconds. We measure an astrometric signal in radial velocity of 276 ms-1, which corresponds to a separation between the two components at the time of the observations of 18 ± 2 milli-Arcseconds. The stars were aligned east-west.We describe a simple optical device to simultaneously record pairs of spectra rotated by 180 degrees, thus reducing systematic effects. We compute and provide the function expressing the shift of the centroid of a seeing-limited image in the presence of a narrow slit. Conclusions. The proposed technique is simple to use and our test shows that it is amenable for deriving astrometry with milliarcsecond accuracy or better, beyond the diffraction limit of the telescope. The technique can be further improved by using simple devices to simultaneously record the spectra with 180 degrees angles. This device together with an optimized data analysis will further reduce the measurement errors. With tachoastrometry, radial velocities and astrometric positions can be measured simultaneously for many double line system binaries in an easy way. The method is not limited to binary stars, but can be applied to any astrophysical configuration in which spectral lines are generated by separate (non-rotational symmetric) regions.

KW - Binaries: Spectroscopic

KW - Techniques: High angular resolution

KW - Techniques: Radial velocities

KW - Techniques: spectroscopic

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