J/A+A/686/A177 VELOCE I. Cepheids High-precision RVs (Anderson+, 2024)
VELOCE I. High-precision radial velocities of Cepheids
Anderson R.I., Viviani G., Shetye S.S., Mowlavi N., Eyer L., Palaversa L.,
Holl B., Blanco-Cuaresma S., Kravchenko K., Pawlak M., Cruz Reyes M.,
Khan S., Netzel H.E., Loebling L., Papics P.I., Postel A., Roelens M.,
Spetsieri Z.T., Thoul A., Zak J., Bonvin V., Martin D.V., Millon M.,
Saesen S., Wyttenbach A., Figueira P., Marmier M., Prins S., Raskin G.,
van Winckel H.
<Astron. Astrophys. 686, A177 (2024)>
=2024A&A...686A.177A 2024A&A...686A.177A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable; Binaries, spectroscopic; Radial velocities
Keywords: techniques: radial velocities - binaries: spectroscopic -
stars: oscillations - stars: variables: Cepheids
Abstract:
We present the first data release of VELOCE, a project dedicated to
measuring high-precision radial velocities (RVs) of Galactic classical
Cepheids (henceforth: Cepheids). VELOCE DR1 comprises 18225 RV
measurements of 258 bona fide classical Cepheids on both hemispheres
collected mainly between 2010 and 2022, as well as 1,161 observations
of 164 additional stars, the majority of which were previously
misclassified as Cepheids. The median per-observation RV uncertainty
for Cepheids is 0.037km/s and reaches 2m/s for the brightest stars
observed with Coralie. Non- variable standard stars were used to
characterize RV zero-point stability and to provide a base for future
cross-calibrations. We determined zero-point differences between
VELOCE and 31 literature data sets using template fitting, which we
also used to investigate linear period changes of 146 Cepheids.
Seventy-three spectroscopic binary Cepheids and 13 candidate binary
Cepheids were identified using VELOCE data alone and are investigated
in detail in a companion paper (VELOCE II). VELOCE DR1 provides
several new insights into the pulsational variability of Cepheids.
Chiefly among these are: a) the most detailed description of the
Hertzsprung progression based on RVs to date, b) the identification of
double-peaked bumps in the pulsation curve, and c) clear evidence that
virtually all Cepheids feature spectroscopic variability signals that
lead to modulated RV variability at the level of tens to hundreds of
m/s that cannot be satisfactorily modeled using single-periodic
Fourier series. We identified 36 stars exhibiting such modulated
variability, of which four also exhibit orbital motion. Linear radius
variations depend strongly on pulsation period, and a steep increase
in slope of the delta R/p vs log P-relation is found near 10 d. This
effect, combined with significant RV amplitude differ- ences at fixed
period challenge the existence of a tight relation between
Baade-Wesselink projection factors and pulsation periods. We
investigated the accuracy of RV time-series measurements, vgamma,
and RV amplitudes published by the ESA mission Gaia's third data
release and determined an offset of 0.65±0.11km/s relative to
VELOCE. Whenever possible, we recommend adopting a single set of
template correlation parameters for distinct classes of large
amplitude variable stars to avoid systematic offsets in v_gamma among
stars belonging to the same class. Peak-to-peak amplitudes of Gaia RVs
exhibit significant (16%) dispersion. Potential differences of RV
amplitudes require further inspection, notably in the context of
projection factor calibration.
Description:
The first data release of the VELOCE project (VELOCE DR1) comprises
18,225 radial velocity measurements (RVs) of 258 bona-fide classical
Cepheids and 1161 RVs of additional targets, most of which were
previously misclassified as Cepheids. The observations were collected
mainly between 2010 and 2022 using two 1.2m telescopes: Euler (Coralie
spectrograph) at ESO La Silla Observatory in Chile, and Mercator
(Hermes spectrograph) at Roque de los Muchachos Observatory on La
Palma, Canary Islands, Spain. Furthermore, we compared and determined
the zero-points differences between our measurements and 31 literature
catalogs, including Gaia DR3 RV time series of classical Cepheids.
Here, we deliver tables specifying the measured literature zero-point
offsets (table 5), period changes (table 6), summary information on
the sample of 258 bona fide single mode Cepheids (table A.1), the
results from the Fourier series modeling of 219 Cepheids (table A.2),
and information for 164 additional stars (table B.1). The full set of
radial velocity measurements is published in FITS format on
https://zenodo.org/records/10793507 .
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table5.dat 102 34 Literature data zero-points
table6.dat 47 146 Linear period change rates (dP/dt)
tablea1.dat 125 258 Bona fide single-mode classical Cepheids
tablea2.dat 120 219 Fourier parameters of modeled Cepheids
tableb1.dat 142 164 Other targets in VELOCE
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/A+A/674/A22 : Gaia DR3. Cross-match with known variable objects
(Gavras+, 2023)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- Ref Literature or instrument reference
24- 25 I2 --- Nstars [1/68] Number of stars used to determine
the zero-point
27- 29 I3 --- Nclusters [1/219] Number of clusters used to determine
the zero-point
31- 36 F6.3 km/s ZP Zero-point difference between VELOCE and
the reference
38- 42 F5.3 km/s e_ZP Uncertainty on the zero-point difference
44-102 A59 --- BibCodes Bibcode for the references
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Star Name of the Cepheid
11- 19 F9.3 s/yr dP/dt Linear period change rate
21- 27 F7.3 s/yr e_dP/dt Uncertainty in the linear period change rate
29- 47 A19 --- Notes Notes on the results
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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- 19 A19 --- Name Name of the Cepheid
21- 22 I2 h RAh Right ascension (J2000)
24- 25 I2 min RAm Right ascension (J2000)
27- 28 I2 s RAs Right ascension (J2000)
30 A1 --- DE- Declination sign (J2000)
31- 32 I2 deg DEd Declination (J2000)
34- 35 I2 arcmin DEm Declination (J2000)
37- 38 I2 arcsec DEs Declination (J2000)
40- 58 A19 --- GaiaDR3 Gaia DR3 source_id
60- 64 F5.1 mag Gmag ? Gaia G magnitude
66- 69 F4.1 mag Bp-Rp ? Gaia GBp-GRp color
71- 72 A2 --- Pmode Pulsation mode classification according to
Gaia DR3
74 A1 --- Binflag [FTU] Binary flag
76- 78 I3 --- NRV [1/929] Number of radial velocity measurements
80- 84 F5.1 --- NFS [2/19]? Number of terms in the Fourier series
86- 95 F10.6 d P ? Pulsation period
97-103 E7.2 d e_P ? Uncertainty on the pulsation period
105-117 F13.6 d E ? Reference epoch at which phi=0 (BJD-2400000)
119-125 E7.2 d e_E ? Uncertainty on the reference epoch
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Name of the Cepheid
21- 22 I2 --- Polydeg [1/20]? Degree of the polynomial used in
conjunction with the Fourier series
24- 26 I3 --- DoF [2/901] Degrees of freedom
28- 36 F9.1 --- Chi2 Chi-squared (Chi2)
38- 45 F8.3 km/s vgamma Radial velocity offset
47- 52 F6.3 km/s P2P Peak-to-peak radial velocity amplitude
54- 59 F6.3 km/s A1 Amplitude of the first Fourier component
61- 66 F6.3 rad phi1 Phase of the first Fourier component
68- 73 F6.4 --- R21 Ratio of the second to the first
Fourier harmonics
75- 78 F4.2 rad phi21 Phase difference between the
second and the first Fourier harmonics
80- 86 F7.4 --- R31 ? Ratio of the third to the first
Fourier harmonics
89- 92 F4.2 rad phi31 ? Phase difference between the
third and the first Fourier harmonics
94-100 F7.4 --- R41 ? Ratio of the fourth to the first
Fourier harmonics
102-106 F5.2 rad phi41 ? Phase difference between the
fourth and the first Fourier harmonics
108-114 F7.4 --- R51 ? Ratio of the fifth to the first
Fourier harmonics
117-120 F4.2 rad phi51 ? Phase difference between the
fifth and the first Fourier harmonics
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 26 A26 --- Name Name of the target
28- 30 I3 --- NRV [0/199] Number of radial velocity
measurements
32 A1 --- CCFpeak [yn] Peak of the cross-correlation function
flag
34 A1 --- CCFodd [yn?] CCF looks significantly different from
those of classical Cepheids flag
36- 44 A9 --- Ncomp Specify if more than one absorption
component was noticed
46- 50 A5 --- Emission Exhibits signs of emission features
52- 53 A2 --- vRV [yn? NA] RV variability flag
55- 56 A2 --- vFWHW [yn? NA] FWHM variability flag
58- 59 A2 --- vAsym [yn? NA] Line asymmetry variability flag
61- 62 A2 --- vLineDepth [yn? NA] Line depth variability flag
64-109 A46 --- CCFnote Additional notes on the CCF
111-129 I19 --- GaiaDR3 Gaia DR3 source_id
131-136 A6 --- Class Gaia DR3 classification
138-142 A5 --- G22 Gavras et al. (2023A&A...674A..22G 2023A&A...674A..22G,
Cat. J/A+A/674/A22) classification
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History:
From Richard I. Anderson, richard.anderson(at)epfl.ch
Acknowledgements:
This research has received support from the European Research Council
(ERC) under the European Union's Horizon 2020 research and innovation
programme (Grant Agreement No. 947660). The Euler telescope is funded
by the Swiss National Science Foundation (SNSF). This research is
based on observations made with the Mercator Telescope, operated on
the island of La Palma by the Flemish Community, at the Spanish
Observatorio del Roque de los Muchachos of the Instituto de
Astrofisica de Canarias. Hermes is supported by the Fund for
Scientific Research of Flanders (FWO), Belgium, the Research Council
of K.U. Leuven, Belgium, the Fonds National de la Recherche
Scientifique (F.R.S.-FNRS), Belgium, the Royal Observatory of Belgium,
the Observatoire de Geneve, Switzerland, and the Thuringer
Landessternwarte, Tautenburg, Germany
(End) Patricia Vannier [CDS] 31-Mar-2024