J/A+A/534/A94 Milky Way Cepheids radial velocities (Storm+, 2011)
Calibrating the Cepheid period-luminosity relation from the infrared surface
brightness technique.
I. The p-factor, the Milky Way relations, and a universal K-band relation.
Storm J., Gieren W., Fouque P., Barnes T.G., Pietrzynski G., Nardetto N.,
Weber M., Granzer T., Strassmeier K.G.
<Astron. Astrophys. 534, A94 (2011)>
=2011A&A...534A..94S 2011A&A...534A..94S
ADC_Keywords: Milky Way ; Stars, variable ; Stars, distances ; Radial velocities
Keywords: stars: variable: Cepheids - stars: fundamental parameters -
stars: distances - distance scale
Abstract:
We determine Period-Luminosity relations for Milky Way Cepheids in the
optical and near-IR bands. These relations can be used directly as
reference for extra-galactic distance determination to Cepheid
populations with solar metallicity, and they form the basis for a
direct comparison with relations obtained in exactly the same manner
for stars in the Magellanic Clouds, presented in an accompanying
paper. In that paper we show that the metallicity effect is very small
and consistent with a null effect, particularly in the near-IR bands,
and we combine here all 111 Cepheids from the Milky Way, the LMC and
SMC to form a best relation. We employ the near-IR surface brightness
(IRSB) method to determine direct distances to the individual Cepheids
after we have recalibrated the projection factor using the recent
parallax measurements to ten Galactic Cepheids and the constraint
that Cepheid distances to the LMC should be independent of pulsation
period. We confirm our earlier finding that the projection factor for
converting radial velocity to pulsational velocity depends quite
steeply on pulsation period, p=1.550-0.186*log(P) in disagrement
with recent theoretical predictions. We find PL relations based
on 70 Milky Way fundamental mode Cepheids of
Mk=-3.33(±0.09)(log(P)-1.0)-5.66(±0.03),
Wvi=-3.26(±0.11)(log(P)-1.0)-5.96(±0.04).
Combining the 70 Cepheids presented here with the results for 41
Magellanic Cloud Cepheids which are presented in an accompanying
paper, we find Mk=-3.30(±0.06)(log(P)-1.0)-5.65(±0.02),
Wvi=-3.32(±0.08)(log(P)-1.0)-5.92(±0.03). We delineate the
Cepheid PL relation using 111 Cepheids with direct distances from the
IRSB analysis. The relations are by construction in agreement with the
recent HST parallax distances to Cepheids and slopes are in excellent
agreement with the slopes of apparent magnitudes versus period
observed in the LMC.
Description:
Repeated high precision radial velocity measurements for 14 galactic
Cepheids obtained with the STELLA telescope and echelle spectrograph
are presented together with the associated time stamps. From these
data radial velocity curves with good phase coverage can be
established. The Cepheids observed are: V496 Aql, TT Aql, VZ Cyg,
ζ Gem, X Pup, AQ Pup, BN Pup, LS Pup, VZ Pup, X Sgr, Y Sgr,
BB Sgr, XX Sgr, YZ Sgr.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 63 14 Star list
table3.dat 45 381 Time stamps and radial velocities
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See also:
J/A+A/534/A95 : LMC Cepheids radial velocities (Storm+, 2011)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
11- 12 I2 h RAh Simbad Hour of Right Ascension (J2000.0)
14- 15 I2 min RAm Simbad Minute of Right Ascension (J2000.0)
17- 20 F4.1 s RAs Simbad Second of Right Ascension (J2000.0)
22 A1 --- DE- Simbad Sign of the Declination (J2000.0)
23- 24 I2 deg DEd Simbad Degree of Declination (J2000.0)
26- 27 I2 arcmin DEm Simbad Arcminute of Declination (J2000.0)
29- 30 I2 arcsec DEs Simbad Arcsecond of Declination (J2000.0)
33- 37 F5.2 mag Bmag Simbad B band magnitude
39- 43 F5.2 mag Vmag Simbad V band magnitude
46- 52 A7 --- SpType Simbad MK spectral type
56- 63 F8.6 [d] logP Period (from table7 of the paper)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Variable star identifier (GCVS)
12- 24 F13.5 d HJD Heliocentric Julian Date
27- 30 F4.2 --- Phase Pulsation phase
32- 38 F7.2 km/s HRV Heliocentric Radial Velocity
42- 45 F4.2 km/s e_HRV Estimated error on the Radial Velocity
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Acknowledgements:
Jesper Storm, jstorm(at)aip.de
References:
Strom et al., Paper II 2011A&A...534A..95S 2011A&A...534A..95S, Cat. J/+A/534/A95
(End) Jesper Storm [AIP, Germany], Patricia Vannier [CDS] 07-Oct-2011