J/A+A/682/A143 V Hya HERMES radial velocity curve (Planquart+, 2024)
A dynamic view of V Hydrae Monitoring of a spectroscopic-binary AGB star
with an alkaline jet.
Planquart L., Jorissen A., Escorza A., Verhamme O., Van Winckel H.
<Astron. Astrophys., 682, A143 (2024)>
=2024A&A...682A.143P 2024A&A...682A.143P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Radial velocities ; Optical ; Infrared
Keywords: techniques: spectroscopic - stars: AGB and post-AGB -
binaries: spectroscopic - stars: individual: V Hydrae -
stars: variables: general - ISM: jets and outflows
Abstract:
The well studied carbon star V Hydrae is known to exhibit a complex
asymmetric environment made of a dense equatorial wind and
high-velocity outflows, hinting at its transition from the AGB phase
to the asymmetric planetary nebula phase. In addition, V Hydrae also
exhibits a long secondary period of 17yr in its light curve,
suggesting the presence of a binary companion that could shape the
circumstellar environment.
In this paper, we aim to confirm the binary nature of V Hydrae by
deriving its orbital parameters and investigating the effect of the
orbital motion on the circumbinary environment.
In a first step, we used a radial-velocity monitoring performed with
the HERMES spectrograph to disentangle the pulsation signal of the AGB
from its orbital motion and to obtain the spectroscopic orbit. We
combined the spectroscopic results with astrometric information to get
the complete set of orbital parameters, including the system
inclination. Next, we reported the time variations of the sodium and
potassium resonance doublets. Finally, following the methods used for
post-AGB stars, we carried out spatio-kinematic modelling of a conical
jet to reproduce the observed spectral-line modulation.
We found the orbital solution of V Hydrae for a period of 17yr. We
correlated the companion passage across the line of sight with the
obscuration event and the blue-shifted absorption of alkaline resonant
lines. Those variations were modelled by a conical jet emitted from
the companion, whose opening angle is wide and whose sky-projected
orientation is found to be consistent with the axis of the large-scale
bipolar outflow previously detected in the radio-emission lines of CO.
We show that the periodic variation seen for V Hydrae is likely to be
due to orbital motion. The presence of a conical jet offers a coherent
model to explain the various features of V Hydrae environment.
Description:
V Hya has been monitored with the HERMES spectrograph mounted on the
1.2m Mercator telescope at La Palma. A total of 130 spectra were taken
on different dates between 2011 and 2023, with an average exposure
time of 900s. The high-resolution mode was used, providing a
resolution of R=86000 over a wavelength range from 3800 to 9000Å.
Objects:
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RA (2000) DE Designation(s)
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10 51 37.26 -21 15 00.3 V Hya = HIP 53085
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 27 100 Radial velocities of V Hya measured with HERMES
(barycentric correction applied)
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- N Sequential number of observation
5- 14 F10.2 d JD Julian date of observation
16- 22 F7.3 km/s RV Radial velocity
24- 27 F4.2 km/s e_RV Radial velocity dispersion
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Apr-2024