J/ApJ/747/50 Distance to Cepheids using the Wesenheit function (Ngeow, 2012)
On the application of Wesenheit function in deriving distance to Galactic
Cepheids.
Ngeow C.-C.
<Astrophys. J., 747, 50 (2012)>
=2012ApJ...747...50N 2012ApJ...747...50N
ADC_Keywords: Stars, distances ; Stars, variable ; Models
Keywords: distance scale - stars: variables: Cepheids
Abstract:
In this paper, we explore the possibility of using the Wesenheit
function to derive individual distances to Galactic Cepheids, as the
dispersion of the reddening-free Wesenheit function is smaller than
the optical period-luminosity (P-L) relation. When compared to the
distances from various methods, the averaged differences between our
results and published distances range from -0.061 to 0.009, suggesting
that the Wesenheit function can be used to derive individual Cepheid
distances. We have also constructed Galactic P-L relations and
selected Wesenheit functions based on the derived distances. A
by-product from this work is the derivation of Large Magellanic Cloud
distance modulus when calibrating the Wesenheit function. It is found
to be 18.531±0.043 mag.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 97 393 Distance to Galactic Cepheids using the Wesenheit
function
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See also:
J/A+A/550/A70 : Galactic & MC Cepheids distance (Groenewegen, 2013)
J/AJ/142/136 : Spectroscopy of Cepheids. l=30-250° (Luck+, 2011)
J/AJ/142/51 : Galactic Cepheids abundance variations (Luck+, 2011)
J/ApJ/715/277 : Insights into the Cepheid distance scale (Bono+, 2010)
J/A+A/476/73 : Calibration of Cepheid P-L relation (Fouque+, 2007)
J/A+A/404/423 : BVI photometry of Galactic Cepheids (Tammann+, 2003)
J/A+AS/143/211 : Galactic Cepheids BVRI photometry (Berdnikov+, 2000)
J/AJ/113/1073 : Abundances in Cepheid Variables (Fry+ 1997)
http://www.astro.utoronto.ca/DDO/research/cepheids/ : the Galactic Cepheid
database of David Dunlap Observatory
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Name of Cepheid
11- 15 A5 --- Type Type of Cepheid from GCVS (CEP, DCEP or DCEPS)
17- 21 F5.3 [d] log(P) [0.16/1.84] log10 of the pulsating period
23- 29 F7.3 mag Bmag [2.3/16.2]?=999.99 The B band mean magnitude (1)
31- 36 F6.3 mag Vmag [1.97/14.64] The V band mean magnitude (1)
38- 44 F7.3 mag Rmag ?=999.99 The R band mean magnitude (1)
46- 51 F6.3 mag Imag The I band mean magnitude (1)
53- 59 F7.3 mag Jmag [0.8/9.8]?=999.99 The J band mean magnitude (1)
61- 67 F7.3 mag Hmag ?=999.99 The H band mean magnitude (1)
69- 75 F7.3 mag Kmag ?=999.99 The K band mean magnitude (1)
77- 83 F7.3 mag E(B-V) [0/1.678]?=999.99 Extinction value (2)
85- 90 F6.2 [Sun] [Fe/H] [-0.7/0.5]?=999.99 Metallicity (3)
92- 97 F6.3 mag muW [5.56/16.18] Distance modulus calculated from
Wesenheit Function (4)
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Note (1): A sample of Galactic Cepheids that have VI-band intensity mean
magnitudes was compiled from Berdnikov et al. 2000 (J/A+AS/143/211),
with updated intensity mean magnitudes adopted from van Leeuwen et al.
(2007MNRAS.379..723V 2007MNRAS.379..723V). Additional Cepheids or the missing VI-band
intensity mean magnitudes were added from the following sources:
Groenewegen (1999A&AS..139..245G 1999A&AS..139..245G), Lanoix et al. (1999MNRAS.308..969L 1999MNRAS.308..969L),
Sandage et al. (1999ApJ...522..250S 1999ApJ...522..250S), Tammann et al. 2003 (J/A+A/404/423),
Fouque et al. 2007 (J/A+A/476/73), and van Leeuwen et al.
(2007MNRAS.379..723V 2007MNRAS.379..723V). In addition, B- and R-band (in the Cousins
system) intensity mean magnitudes were available for 387 and 334
Cepheids, respectively, from the cited reference. Finally, JHK-band
intensity mean magnitudes in the SAAO (South African Astronomical
Observatory) system are available for 229 Cepheids from van Leeuwen et
al. (2007MNRAS.379..723V 2007MNRAS.379..723V). They were converted to 2MASS (Two-Micron
All Sky Survey, Skrutskie et al. 2006, Cat. VII/233) systems using the
color transformation equations given on the 2MASS Web site.
Note (2): E(B-V) for 10 Cepheids, which do not have the entries from Fernie
et al. (1995IBVS.4148....1F 1995IBVS.4148....1F), were taken from either Fouque et al.
(2007, Cat. J/A+A/476/73) or van Leeuwen et al. (2007MNRAS.379..723V 2007MNRAS.379..723V).
Note (3): [Fe/H] values are available from Luck & Lambert 2011 (Cat.
J/AJ/142/136, 254 Cepheids), Luck et al. 2011 (Cat. J/AJ/142/51, 76
Cepheids), Romaniello et al. (2008A&A...488..731R 2008A&A...488..731R, VW Cen and LS Pup),
Andrievsky et al. (2003AN....324..532A 2003AN....324..532A, X Sgr), Yong et al.
(2006AJ....131.2256Y 2006AJ....131.2256Y, HQ Car), and Fry and Carney 1997 (Cat.
J/AJ/113/1073, QZ Nor). See section 2 for further details.
Note (4): Distance moduli to Galactic Cepheids can be found using the
following equation (1): µW=I-1.55(V-I)+3.313log(P)+2.639 where
one only needs to know the pulsating period, P, and the VI-band
intensity mean magnitudes (the I band is in the Cousins system)
for a given Cepheid. The error on µW is taken to be
σW=((0.069)2+(0.043)2)0.5=0.081mag. See section 2 and 4.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Sep-2013