J/ApJ/824/1 Timing data for the classical Cepheid l Car (Neilson+, 2016)
The secret lives of Cepheids: evolution, mass-loss, and ultraviolet emission
of the long-period classical Cepheid.
Neilson H.R., Engle S.G., Guinan E.F., Bisol A.C., Butterworth N.
<Astrophys. J., 824, 1-1 (2016)>
=2016ApJ...824....1N 2016ApJ...824....1N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry
Keywords: stars: evolution; stars: fundamental parameters;
stars: individual: l Car; stars: mass-loss; stars: variables: Cepheids
Abstract:
The classical Cepheid l Carinae is an essential calibrator of the
Cepheid Leavitt Law as a rare long-period Galactic Cepheid.
Understanding the properties of this star will also constrain the
physics and evolution of massive (M≥8M☉) Cepheids. The
challenge, however, is precisely measuring the star's pulsation period
and its rate of period change. The former is important for calibrating
the Leavitt Law and the latter for stellar evolution modeling. In this
work, we combine previous time-series observations spanning more than
a century with new observations to remeasure the pulsation period and
compute the rate of period change. We compare our new rate of period
change with stellar evolution models to measure the properties of l
Car, but find models and observations are, at best, marginally
consistent. The results imply that l Car does not have significantly
enhanced mass-loss rates like that measured for δ Cephei. We
find that the mass of l Car is about 8-10M☉. We present Hubble
Space Telescope Cosmic Origins Spectrograph observations that also
differ from measurements for δ Cep and β Dor. These
measurements further add to the challenge of understanding the physics
of Cepheids, but do hint at the possible relation between enhanced
mass-loss and ultraviolet emission, perhaps both due to the strength
of shocks propagating in the atmospheres of Cepheids.
Description:
To measure the period and rate of period change for l Car, we use
published photometric data spanning from 1871 to 1990 which we
complement with new observations for the year 2012 taken by one of us
(Butterworth). See table 1.
Six UV observations of l Car were carried out in 2012-2013 with the
HST-COS. Also as part of "The Secret Lives of Cepheids" program, an
X-ray observation of l Car was carried out with XMM-Newton in 2010
February. See section 4 for further details.
Objects:
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RA (ICRS) DE Designation(s) (Period)
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09 45 14.81 -62 30 28.5 l Car = TYC 8946-3219-1 (P=35.5)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 77 115 Published and new timing data for l Car
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/285 : Photoelectric observations of Cepheids in UBV(RI)c (Berdnikov, 2008)
II/224 : Catalogue of Stellar Diameters (CADARS) (Pasinetti-Fracassini+ 2001)
J/MNRAS/455/4231 : Coralie radial velocities for l Car (Anderson+, 2016)
J/A+A/584/A80 : Pulsation model for delta Cep and eta Aql (Merand+, 2015)
J/MNRAS/446/4008 : RT Aur and SZ tau UBV light curves (Evans+, 2015)
J/AN/336/70 : Veloc. & proper motions of Galactic Cepheids (Mel'nik+, 2015)
J/A+A/566/L10 : Cepheid radial velocity amplitude modulations (Anderson, 2014)
J/A+A/566/A37 : Iron abundances for 42 Galactic Cepheids (Genovali+, 2014)
J/A+A/550/A70 : Galactic & MC Cepheids distance (Groenewegen, 2013)
J/ApJ/759/146 : Spitzer/IRAC photom. for 37 Galactic Cepheids (Monson+, 2012)
J/MNRAS/420/1590 : Abundances of classical Cepheids (Acharova+, 2012)
J/AJ/142/51 : Galactic Cepheids abundance variations (Luck+, 2011)
J/MNRAS/410/190 : Young runaway stars within 3kpc (Tetzlaff+, 2011)
J/ApJS/190/203 : 3.6 years of DIRBE NIR stellar light curves (Price+, 2010)
J/A+A/504/959 : Amplitudes of single-mode Cepheids (Klagyivik+, 2009)
J/A+A/502/951 : HARPS observations of nine galactic Cepheids (Nardetto+, 2009)
J/AcA/58/313 : LMC Cepheids in OGLE and MACHO data (Poleski+, 2008)
J/A+A/476/307 : Period variations in galactic RRab stars (Le Borgne+, 2007)
J/A+A/453/309 : HARPS observations of nine galactic Cepheids (Nardetto+, 2006)
J/MNRAS/362/1167 : Radial velocities of 14 southern Cepheids (Petterson+, 2005)
J/A+A/428/587 : Cepheids BVRIJHK dereddened magnitudes (Kervella+, 2004)
J/ApJS/154/673 : COBE DIRBE Point Source Catalog (Smith+, 2004)
J/A+AS/143/211 : Galactic Cepheids BVRI photometry (Berdnikov+, 2000)
http://www.aavso.org/ : American Association of Variable Star Observers page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d HJD Heliocentric Julian Date of maximum
13- 16 I4 --- Epoch [-932/534] Epoch number
18- 24 F7.4 d (O-C) [-8.7/8.3] Residual
26- 28 F3.1 --- Weight [0.5/5] Weighting value
30- 57 A28 --- Ref Reference (Author and year) (1)
59- 77 A19 --- BibCode Bibcode for Ref if available
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Note (1): See Section 2 for a discussion of the times of maximum reported
by Innes (1897AJ.....17...95I 1897AJ.....17...95I).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 09-Aug-2016