J/A+A/707/A142 Abundances for 60 Classical Cepheids (DCEPs) (Trentin+, 2026)
Cepheid Metallicity in the Leavitt Law (C- MetaLL) survey.
VIII: Spectroscopic detection or rare earth dysprosium, erbium, lutetium, and
thorium in classical Cepheids.
Trentin E., Catanzaro G., Ripepi V., Luongo E., Marconi M., Musella I.,
Cusano F., Storm J., Bhardwaj A., De Somma G., Leccia S., Sicignano T.,
Molinaro R., Testa V.
<Astron. Astrophys. 707, A142 (2026)>
=2026A&A...707A.142T 2026A&A...707A.142T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Abundances ; Optical ; Photometry
Keywords: stars: abundances - stars: distances - stars: fundamental parameters -
stars: variables: Cepheids - Galaxy: disc
Abstract:
Classical Cepheids (DCEPs) are among the most important distance
calibrators thanks to the correlation between their period and
luminosity (PL relation), and play a crucial role in the calibration
as the first rung of the extragalactic distance ladder. Given their
typical age, they also constitute an optimal tracer of the young
population in the Galactic disc.
We aim to increase the number of available DCEPs with high-resolution
spectroscopic metallicities, study the galactocentric radial gradients
of several chemical elements, and analyse the spatial distribution of
the Galactic young population of stars in the Milky Way disc.
We performed a complete spectroscopical analysis of 136 spectra
obtained from three different high- resolution spectrographs, for a
total of 60 DCEPs. More than half have pulsational periods longer than
15 days, up to 70 days, doubling the number of stars in our sample
with P>15d. We derived radial velocities, atmospheric parameters,
and chemical abundances for up to 33 different species.
We present an updated list of trusted spectroscopic lines for the
detection and estimation of chemical abundances. We used this new set
to revisit the abundances already published in the context of the
C-MetaLL (Cepheids- Metallicity in the Leavitt Law) survey and
increase the number of available chemical species. For the first time
(to our knowledge), we present the estimation of abundances for
Cepheids for dysprosium (Dy, Z=66), as well as a systematic
estimation of erbium (Er, Z=68), lutetium (Lu, Z=71), and thorium
(Th, Z=90) abundances.
We calculated a galactic radial gradient for [Fe/H] with a slope of
-0.064±0.002dex/kpc, in good agreement with recent literature
estimation. The other elements also exhibit a clear negative radial
trend, with this effect diminishing and eventually disappearing for
heavier neutron-capture elements. Depending on the proposed spiral
arms model present in several literature sources, our most external
stars agree on tracing either the Perseus, the Norma-Outer, or both
the Outer and the association Outer-Scutum-Centaurus (OSC) arms.
Description:
In this eighth work in the context of the C-MetaLL project, we
collected and analysed a total of 136 spectra, corresponding to 60
DCEPs, 7 of which are repeated targets already published in previous
C-MetaLL works, and 2 are SMC stars.
A sample of 23 stars (29 spectra in total) were observed at the
European Southern Observatory (ESO) during period P112 (2023-2024)
under proposal 112.25NA.
A sample of 15 stars (for a total of 44 spectra) was observed
with the High Accuracy Radial velocity Planet Searcher for the
Northern hemisphere (HARPS-N) at the 3.5m Telescopio Nazionale Galileo
(TNG), during period 47 (proposal A47TAC_18, July-August 2024).
A sample of 22 stars (for a total of 63 spectra) was observed with
the Potsdam Echelle Polarimetric and Spectroscopic Instrument
(PEPSI), the fibre-feed high-resolution optical echelle spectrograph
for the Large Binocular Telescope (LBT). The observations were carried
out in two periods (proposals IT-2019B-014 and IT-2021202224) in
2019-2020 and 2021-2022.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 202 60 Main properties of the 60 programme DCEPs
tablea2.dat 149 137 Observation information and atmospheric
parameters for the 137 spectra analysed
in this work
tablea3.dat 95 201 List of observed spectral lines in our spectra
tablea4.dat 788 340 Estimated chemical abundances for the whole
C-MetaLL dataset of 340 stars
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 28 A28 --- Star Literature name of the DCEP
30- 48 I19 --- GaiaDR3 Gaia DR3 identifier
50- 67 F18.14 deg RAdeg Right ascension (J2000)
69- 88 F20.16 deg DEdeg Declination (J2000)
90-108 F19.16 d Period Period of pulsation
110-111 A2 --- Mode Mode of pulsation
114-123 F10.7 mag Gmag G magnitude
125-134 F10.7 mag GBPmag GBP magnitude
136-145 F10.7 mag GRPmag GRP magnitude
147-154 F8.5 kpc rgc Galactocentric distance
156-162 F7.5 kpc e_rgc Galactocentric distance error
164-170 F7.5 deg phi Azimutal angle
172-180 F9.5 kpc h Vertical distance from the disc
182-194 A13 --- Source Instrument used to observe the star
196-202 A7 --- Notes Origin of the periods and modes
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 28 A28 --- Star Name of the star
30 A1 --- N Multiplicity index when several spectra for
the same star
32- 47 F16.10 d HJD Heliocentric Julian Day at mid exposure
49- 59 F11.5 --- Phase Phase
61- 69 F9.4 s ExpTime Exposure time
71- 78 A8 --- SNR Signal-to-noise ratio
80- 88 F9.4 km/s HRV Heliocentric radial velocity
90- 94 F5.3 km/s e_HRV Heliocentric radial velocity error
96- 99 I4 K Teff Effective temperature
101-103 I3 K e_Teff Effective temperature error
105-109 F5.3 km/s vmic Microturbulent velocity
111-115 F5.3 km/s e_vmic Microturbulent velocity error
117-121 F5.3 [cm/s2] logg Logarithm of the gravity
123-127 F5.3 [cm/s2] e_logg logg error
129-130 I2 km/s vbroad Broadening velocity
132-135 F4.1 km/s e_vbroad vbroad error
137-149 A13 --- Source Instrument used to observe the star
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- El Element and ionization state
7- 14 F8.3 0.1nm lambda Wavelength
16- 22 F7.3 --- loggf Oscillator strength, log(gf)
24- 44 F21.18 eV Ei Lower level energy in eV
46- 49 F4.1 eV Ji Lower level total angular momentum
51- 69 F19.16 --- Ef Upper level energy in eV
71- 73 F3.1 --- Jf Upper level total angular momentum
75- 79 F5.2 --- loggammar Radiative damping constant in logarithmic form
81- 85 F5.2 --- loggammaS Stark damping constant in logarithmic form
87- 91 F5.2 --- loggammaW Van der Waals damping constant
in logarithmic form
93- 95 A3 --- Comment Further info of the line
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 28 A28 --- Star Name of the star
30- 35 F6.2 --- [C/H] Carbon abundance in [X/H] form
37- 42 F6.2 --- e_[C/H] ?=-99 Carbon abundance error
44- 49 F6.2 --- [O/H] ?=-99 Oxygen abundance in [X/H] form
51- 56 F6.2 --- e_[O/H] ?=-99 Oxygen abundance error
58- 69 F12.9 --- [Na/H] Sodium abundance in [X/H] form
71- 74 F4.2 --- e_[Na/H] Sodium abundance error
76- 95 F20.16 --- [Mg/H] ?=-99 Magnesium abundance in [X/H] form
97-102 F6.2 --- e_[Mg/H] ?=-99 Magnesium abundance error
104-116 E13.9 --- [Al/H] ?=-99 Alluminium abundance in [X/H] form
117-122 F6.2 --- e_[Al/H] ?=-99 Alluminium abundance error
124-144 F21.17 --- [Si/H] ?=-99 Silicon abundance in [X/H] form
146-151 F6.2 --- e_[Si/H] ?=-99 Silicon abundance error
153-173 F21.17 --- [S/H] ?=-99 Solfur abundance in [X/H] form
175-180 F6.2 --- e_[S/H] ?=-99 Sulfur abundance error
182-194 E13.9 --- [Ca/H] Calcium abundance in [X/H] form
196-199 F4.2 --- e_[Ca/H] Calcium abundance error
201-220 F20.17 --- [Sc/H] Scandium abundance in [X/H] form
222-225 F4.2 --- e_[Sc/H] Scandium abundance error
227-239 F13.9 --- [Ti/H] ?=-99 Titanium abundance in [X/H] form
241-246 F6.2 --- e_[Ti/H] ?=-99 Titanium abundance error
248-260 E13.9 --- [V/H] Vanadium abundance in [X/H] form
262-265 F4.2 --- e_[V/H] Vanadium abundance error
267-286 F20.16 --- [Cr/H] ?=-99 Chromium abundance in [X/H] form
288-293 F6.2 --- e_[Cr/H] ?=-99 Chromium abundance error
295-307 F13.9 --- [Mn/H] ?=-99 Manganese abundance in [X/H] form
308-313 F6.2 --- e_[Mn/H] ?=-99 Manganese abundance error
315-326 F12.9 --- [Fe/H] Iron abundance in [X/H] form
328-331 F4.2 --- e_[Fe/H] Iron abundance error
333-346 F14.10 --- [Co/H] Cobalt abundance in [X/H] form
347-352 F6.2 --- e_[Co/H] ?=-99 Cobalt abundance error
354-366 E13.9 --- [Ni/H] ?=-99 Nickel abundance in [X/H] form
368-373 F6.2 --- e_[Ni/H] ?=-99 Nickel abundance error
375-394 E20.17 --- [Cu/H] ?=-99 Copper abundance in [X/H] form
395-400 F6.2 --- e_[Cu/H] ?=-99 Copper abundance error
402-414 F13.9 --- [Zn/H] ?=-99 Zinc abundance in [X/H] form
416-421 F6.2 --- e_[Zn/H] ?=-99 Zinc abundance error
423-428 F6.2 --- [Sr/H] ?=-99 Strontium abundance in [X/H] form
430-435 F6.2 --- e_[Sr/H] ?=-99 Strontium abundance error
437-456 E20.17 --- [Y/H] ?=-99 Yttrium abundance in [X/H] form
458-463 F6.2 --- e_[Y/H] ?=-99 Yttrium abundance error
465-484 E20.18 --- [Zr/H] ?=-99 Zirconium abundance in [X/H] form
486-491 F6.2 --- e_[Zr/H] ?=-99 Zirconium abundance error
493-497 F5.2 --- [Ba/H] Barium abundance in [X/H] form
499-503 F5.2 --- e_[Ba/H] Barium abundance error
505-517 E13.9 --- [La/H] ?=-99 Lanthanum abundance in [X/H] form
519-524 F6.2 --- e_[La/H] ?=-99 Lanthanum abundance error
526-539 F14.10 --- [Ce/H] ?=-99 Cerium abundance in [X/H] form
541-546 F6.2 --- e_[Ce/H] ?=-99 Cerium abundance error
548-560 F13.9 --- [Pr/H] ?=-99 Praseodymium abundance in [X/H] form
562-567 F6.2 --- e_[Pr/H] ?=-99 Praseodymium abundance error
569-581 F13.9 --- [Nd/H] ?=-99 Neodymium abundance in [X/H] form
583-588 F6.2 --- e_[Nd/H] ?=-99 Neodymium abundance error
590-601 F12.8 --- [Sm/H] ?=-99 Samarium abundance in [X/H] form
603-608 F6.2 --- e_[Sm/H] ?=-99 Samarium abundance error
610-622 F13.9 --- [Eu/H] ?=-99 Europium abundance in [X/H] form
624-629 F6.2 --- e_[Eu/H] ?=-99 Europium abundance error
631-638 F8.4 --- [Gd/H] ?=-99 Gadolinium abundance in [X/H] form
640-645 F6.2 --- e_[Gd/H] ?=-99 Gadolinium abundance error
647-666 F20.16 --- [Dy/H] ?=-99 Dysprosium abundance in [X/H] form
668-687 F20.16 --- e_[Dy/H] ?=-99 Dysprosium abundance error
689-707 F19.15 --- [Er/H] ?=-99 Erbium abundance in [X/H] form
709-727 F19.15 --- e_[Er/H] ?=-99 Erbium abundance error
729-748 F20.16 --- [Lu/H] ?=-99 Lutetium abundance in [X/H] form
750-769 F20.16 --- e_[Lu/H] ?=-99 Lutetium abundance error
771-776 F6.2 --- [Th/H] ?=-99 Thorium abundance in [X/H] form
778-782 F5.1 --- e_[Th/H] ?=-99 Thorium abundance error
784-788 A5 --- Source Instrument used to observe the star
--------------------------------------------------------------------------------
Acknowledgements:
Erasmo Trentin, erasmo.trentin(at)inaf.it
References:
Ripepi et al., Paper I 2021MNRAS.508.4047R 2021MNRAS.508.4047R, Cat. J/MNRAS/508/4047
Trentin et al., Paper II 2023MNRAS.519.2331T 2023MNRAS.519.2331T
Molinaro et al., Paper III 2023MNRAS.520.4154M 2023MNRAS.520.4154M
Trentin et al., Paper IV 2024A&A...681A..65T 2024A&A...681A..65T, Cat. J/A+A/681/A65
Bhardwaj et al., Paper V 2024A&A...683A.234B 2024A&A...683A.234B, Cat. J/A+A/683/A234
Trentin et al., Paper VI 2024A&A...690A.246T 2024A&A...690A.246T
(End) Patricia Vannier [CDS] 02-Feb-2026