J/ApJ/775/45 PTI carbon star angular size survey (van Belle+, 2013)
The PTI carbon star angular size survey: effective temperatures and
non-sphericity.
van Belle G.T., Paladini C., Aringer B., Hron J., Ciardi D.
<Astrophys. J., 775, 45 (2013)>
=2013ApJ...775...45V 2013ApJ...775...45V
ADC_Keywords: Stars, carbon ; Infrared sources ; Interferometry ;
Stars, diameters ; Photometry ; Surveys
Keywords: infrared: stars; instrumentation: high angular resolution;
instrumentation: interferometers; stars: carbon; stars: distances;
stars: fundamental parameters
Abstract:
We report new interferometric angular diameter observations of 41
carbon stars observed with the Palomar Testbed Interferometer. Two of
these stars are CH carbon stars and represent the first such
measurements of this subtype. Of these, 39 have Yamashita spectral
classes and are of sufficiently high quality that we can determine the
dependence of effective temperature on spectral type. We find that
there is a tendency for the effective temperature to increase with
increasing temperature index by ∼120K per step, starting at
Teff≃2500K for C3, y, although there is a large amount of scatter
in this relationship. Overall, the median effective temperature of the
carbon star sample is 2800±270 K and the median linear radius is
360±100R☉. We also find agreement, on average within 15K, with
the Teff determinations of Bergeat et al. (J/A+A/369/178) and a
refinement of the carbon star angular size prediction based on V & K
magnitudes is presented that is good to an rms of 12%. A subsample of
our stars have sufficient {u, v} coverage to permit non-spherical
modeling of their photospheres, and a general tendency for detection
of statistically significant departures from sphericity with
increasing interferometric signal-to-noise is seen. The implications
of most -and potentially all- carbon stars being non-spherical is
considered in the context of surface inhomogeneities and a
rotation-mass-loss connection.
Description:
The PTI was an 85-110m (H and K bands: 1.6um and 2.2um) interferometer
located at Palomar Observatory in San Diego County, CA. The data from
PTI considered herein cover the range from the beginning of 1998 until
the cessation of operations in 2009.
For each of the target stars observed in this investigation, a
bolometric flux (FBOL) estimate was established from the SED fits.
This fit was accomplished using literature photometry values, with
spectra from our carbon star models (Section 2.2 and Figure 7). See
table 3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 41 Target observed by Palomar Testbed Interferometer
table2.dat 98 16 Parameters of ellipsoidal fits to angular size
data for those stars with semi-orthogonal NS
and NW baseline data
table3.dat 105 432 Target photometry used in SED fits (for 41 stars)
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See also:
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)
II/271 : TASS Mark IV patches photometric catalog, version 2 (Droege+, 2007)
III/227 : General Catalog of galactic Carbon stars, 3d Ed. (Alksnis+ 2001)
III/150 : Perkins Revised MK Types for the Cooler Stars (Keenan+ 1989)
II/157 : Photoelectric Photometry in Vilnius system (Straizys+ 1989)
J/other/A+ARV/20.51 : Rapidly rotating stars (Van Belle, 2012)
J/ApJ/732/39 : Rotational velocities of K giant stars (Carlberg+, 2011)
J/ApJS/193/17 : IRC+10216 at 293-355GHz (Patel+, 2011)
J/A+A/503/913 : Synthetic spectrophotom. for C-rich giants (Aringer+, 2009)
J/ApJ/694/1085 : Radii of exoplanet host stars (van Belle+, 2009)
J/ApJS/176/276 : PTI calibrator catalog (van Belle+, 2008)
J/MNRAS/369/751 : Near-infrared photometry of carbon stars (Whitelock+, 2006)
J/ApJS/154/673 : COBE DIRBE Point Source Catalog (Smith+, 2004)
J/AJ/126/2048 : NStars project: the Northern Sample. I. (Gray+, 2003)
J/A+A/390/967 : Carbon-rich giants in the HR diagram (Bergeat+, 2002)
J/A+A/390/511 : Millimetre obs. of carbon stars. II. (Groenewegen+, 2002)
J/A+A/369/178 : Effective temperatures of carbon-rich stars (Bergeat+, 2001)
J/A+AS/146/217 : Library of Spectra (0.5-2.5um) of Cool Stars (Lancon+ 2000)
J/A+A/342/773 : Hot carbon stars B-V colour excess (Bergeat+ 1999)
J/A+AS/139/433 : RV and vsini of evolved stars (de Medeiros+ 1999)
J/A+A/321/236 : Reddening and fluxes of carbon stars (Knapik+ 1997)
J/A+A/310/933 : C isotopic ratio in N- and SC-type stars (Ohnaka+, 1996)
J/ApJS/105/419 : Spectral Atlas of Carbon Stars (Barnbaum+ 1996)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Target name
11- 19 A9 --- AName Alternative ID
21- 22 I2 h RAh Hour of right ascension (J2000)
24- 25 I2 min RAm Minute of right ascension (J2000)
27- 30 F4.1 s RAs Second of right ascension (J2000)
32 A1 --- DE- Sign of declination (J2000)
33- 34 I2 deg DEd Degree of declination (J2000)
36- 37 I2 arcmin DEm Arcminute of declination (J2000)
39- 42 F4.1 arcsec DEs Arcsecond of declination (J2000)
44- 45 I2 --- V2 [1/96]? Visibility points used in fitting
θUD
47- 49 I3 --- NV2 [1/116]? Number of visibility points available
(3σ outliers were discarded)
51- 55 F5.3 mas theta [1.4/4.9]? Resultant uniform disk angular size
(θUD)
57- 61 F5.3 mas e_theta [0.005/0.2]? Formal fitting error on theta (1)
63 A1 --- f_chi2 i: ∞
64- 68 F5.3 --- chi2 ? χ2 fit
70- 74 F5.3 --- Res ? Average residual
76- 78 A3 --- Group Group (2)
80- 86 A7 --- Var Variability type (3)
88- 91 F4.2 mag Amp [0.3/4.7]? Amplitude (3)
93- 94 A2 --- Band Band (V, B, p=photographic or Hp=Hipparcos)
96- 99 F4.2 mag Amp1 [0.4/2.8]? AFOEV amplitude (4)
101-104 F4.2 mag Amp2 [0.1/1.7]? HIP amplitude
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Note (1): For ensuing computations that make use of θUD, an error floor
of ±4.6% will be used, as per the discussion at the end of
Section 2.6.2.
Note (2): From the group designations in Bergeat et al. (2001, J/A+A/369/178),
as discussed in Section 4.2. Teff calibration for the CV groups as:
-----------------------------------------------------------
Group N Teff Teff
(this work) (Bergeat+, 2001, J/A+A/369/178)
------------------------------------------------------------
CV2 5 3145±315K 3130± 70K
CV3 12 2916±206K 2940± 80K
CV4 5 2778± 69K 2790±130K
CV5 9 2638±154K 2720±135K
CV6 4 2585±158K 2385±110K
------------------------------------------------------------
Note (3): Variability type and amplitude from the AAVSO Variability Index
(Watson et al. 2012, B/vsx)
Note (4): AFOEV = Association Francaise des Observateurs d'Etoiles Variables
http://cdsarc.u-strasbg.fr/afoev/
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Set [Na] Set (a=all baselines) (1)
3- 11 A9 --- Name Star identifier
13- 17 F5.3 mas theta [1.4/3.9] Uniform disk diameter fit with a
single-parameter circle (θcirc)
19- 23 F5.3 mas e_theta [0.004/0.03] theta uncertainty
25- 29 F5.3 mas a [1.6/3.96] Major axis
31- 35 F5.3 mas e_a [0.02/0.2]? Major axis uncertainty
37- 41 F5.3 mas b [1.4/3.6] Minor axis
43- 47 F5.3 mas e_b [0.01/0.2]? Minor axis uncertainty
49- 51 I3 deg PA [-78/76] Position angle φ
53- 54 I2 deg e_PA [1/42]? PA uncertainty
56- 58 F3.1 --- chi2e [0.1/3.8] χ2ν,ellipse value
60- 63 F4.1 --- chi2c [0.3/14.1] χ2ν,circle value
65- 68 F4.1 --- Delchi2 [-0.2/14.1] Δχ2ν value
70- 74 F5.3 mas thetaEq [1.6/3.8] Equivalent angular size
(θequiv=(ab)0.5)
76- 80 F5.3 --- Ratio [0.9/1.1] Ratio of equivalent angular size to
circular angular size
(θequiv/θcirc)
82- 86 F5.3 --- Oblat [0.01/0.2] Oblateness (Oab=a/b-1)
88- 92 F5.3 --- E_Oblat [0.01/0.1]? Positive error in Oblat
94- 98 F5.3 --- e_Oblat [0.01/0.2]? Negative error in Oblat
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Note (1): Code as follows:
N = Check stars (NS, NW baselines only)
a = Check stars (all baselines)
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star identifier
11- 17 A7 --- Syst Photometry system (2Mass, Cousins, Johnson or
Vilnius)
19- 20 A2 --- Band Bandpass (U, V, Rc, Ic, J, H, K, Ks, L, M, P,
S, X, Y or Z) (1)
22- 26 F5.2 mag mag [1.01/15.4]? Observed magnitude in Band (1)
28- 31 F4.2 mag e_mag [0.04/2.4]? Magnitude uncertainty
33- 37 I5 nm lambda [1000/12000]? Wavelength (1)
39- 42 I4 nm Width ? Bandwidth
44- 49 F6.2 Jy Flux [-36.1/107.2]? Observed flux in lambda (1)
51- 56 F6.2 Jy e_Flux [0.05/384]? Uncertainty in Flux
58- 83 A26 --- Auth Author(s) of the reference for mag or Flux
87-105 A19 --- BibCode Bibcode of the reference for mag or Flux
when available
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Note (1): The collections of photometry used in the SED fitting routine for
all objects. Refer to Section 3.1 for details.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Mar-2015