J/A+A/710/A187 Photometry and RVs of anomalous Cepheids (Wielgorski+, 2026)
Period-luminosity relations, projection factor and radii of anomalous Cepheids.
Wielgorski P., Pietrzynski G., Gieren W., Zgirski B., Narloch W., Hajdu G.,
Storm J., Nardetto N., Kervella P., Pilecki B., Gorski M., Smolec R.,
Salinas R., Graczyk D., Hocde V., Karczmarek P., Taormina M., Pych W.,
Netzel H., Chini R., Hodapp K., Kaluszynski M., Pozo Nunez F., Kotysz K.,
Mozdzierski D., Mikolajczyk P., Kolaczek-Szymanski P.
<Astron. Astrophys. 710, A187 (2026)>
=2026A&A...710A.187W 2026A&A...710A.187W (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry, infrared ; Optical ;
Radial velocities
Keywords: stars: distances - stars: variables: Cepheids - Magellanic Clouds -
distance scale - infrared: stars
Abstract:
Anomalous Cepheids are radially pulsating stars observed in dwarf
galaxies, the Galactic bulge and halo, and globular clusters.
Similarly to other radially pulsating stars, they can be used as
distance indicators through their Period-Luminosity Relations (PLRs)
and the geometrical Baade-Wesselink (BW) method.
We aim to calibrate the zero-point of the distance scale of Anomalous
Cepheids using nearby representatives of this class of pulsating
stars.
We collected optical and near-infrared photometry and spectra for a
sample of nearby Anomalous Cepheids with two telescopes located at the
Rolf Chini Cerro Murphy Observatory (former Observatory Cerro
Armazones) and optical telescopes offered by the Las Cumbres
Observatory, and with instruments hosted and operated by the European
Southern Observatory. Using parallaxes measured by the Gaia space
mission and mean magnitudes from our new photometry, we calibrate the
zero-point of the PLRs in Johnson B, V, 2MASS J, H, Ks, and
Pan-STARRS g, r, i passbands and selected Wesenheit indices. Slopes
are adopted from the PLRs of the Large Magellanic Cloud Anomalous
Cepheids from the literature. Using the surface brightness-colour
relation version of the BW technique, we also determined the
projection factors and mean radii of three nearby Anomalous Cepheids.
Precision of the measured zero-points is at the level of
0.04-0.05mag and their systematic uncertainty is estimated to about
0.1mag. We used our zero-points and literature photometry of the
Large Magellanic Cloud Anomalous Cepheids to measure the distance
modulus of this galaxy and obtained a value of
18.454±0.045(statistical) mag, in a very good agreement with the
most accurate value from eclipsing binaries. The obtained projection
factors are 1.38±0.13, 1.59±0.21 and 1.35±0.14 for V716 Oph, XX
Vir and UY Eri, respectively. We suspect that the very high projection
factor of XX Vir is the result of the underestimated parallax of this
star in the Gaia catalogue as its radius and absolute brightness are
also higher than expected for Anomalous Cepheids at this period. The
radii measured for V716 Oph and UY Eri are in agreement with the
period-radius relation obtained from the Large Magellanic Cloud
Anomalous Cepheids.
Description:
We collected photometric time-series data for our sample stars
in Johnson B, V, 2MASS J, H and Ks, and Pan-STARRS g, r, i passbands.
For three anomalous Cepheids from our Milky Way sample we collected
time-series of spectra.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 35 8 Sample stars
table1.dat 38 1372 Photometry of 8 Milky Way anomalous Cepheids
table4.dat 45 92 Radial velocity measurements of 3 Milky Way
anomalous Cepheids
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Star Name of the star
11- 12 I2 h RAh Simbad right ascension (J2000)
14- 15 I2 min RAm Simbad right ascension (J2000)
17- 21 F5.2 s RAs Simbad right ascension (J2000)
23 A1 --- DE- Simbad declination sign (J2000)
24- 25 I2 deg DEd Simbad declination (J2000)
27- 28 I2 arcmin DEm Simbad declination (J2000)
30- 33 F4.1 arcsec DEs Simbad declination (J2000)
35 A1 --- fRV [+] + indicates RV data in table4.dat
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Star Name of the star
10- 11 A2 --- Filter Photometric passband (1)
13- 27 F15.7 d HJD Heliocentric Julian Date
29- 33 F5.2 mag mag Magnitude in filter
35- 38 F4.2 mag e_mag Uncertainty of magnitude
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Note (1): Photometric passbands are BV, JHKs, gri.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Star Name of the star
10- 22 F13.5 d HJD Heliocentric Julian Date
24- 31 F8.3 km/s RV Radial velocity
33- 37 F5.3 km/s e_RV Uncertainty of radial velocity
39- 45 A7 --- Inst Instrument used to obtain the spectrum,
CORALIE, FEROS, HARPS and UVES
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Acknowledgements:
Piotr Wielgorski, pwielgorski(at)gmail.com
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 13-Apr-2026