J/A+A/542/A116 Rotation in A-F stars (Ammler-von Eiff+, 2012)
New measurements of rotation and differential rotation in A-F stars:
Are there two populations of differentially rotating stars?
Ammler-von Eiff M., Reiners A.
<Astron. Astrophys. 542, A116 (2012)>
=2012A&A...542A.116A 2012A&A...542A.116A
ADC_Keywords: Stars, A-type ; Stars, F-type ; Stars, nearby ;
Rotational velocities
Keywords: stars: rotation - stars: fundamental parameters -
Hertzsprung-Russell and C-M diagrams
Description:
Measurements of projected rotational velocities and the rotational
profile of stars with spectral types A-F are presented. This work
completes previous measurements by line profile analysis. New spectra
with high signal-to-noise ratio were taken with the high-resolution
CES and FEROS spectrographs operated by ESO at La Silla, Chile.
Stellar rotation is studied in inverse wavelength space analysing the
first two zeros of the Fourier transform of the overall broadening
profile. Rigid and differential rotation can be distinguished in the
case of rapid rotation. New and previous measurements are compiled and
made available. The data are supplemented by a homogeneous compilation
of basic stellar data from photometry. Data are flagged when there are
indications of multiplicity.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 95 192 Results obtained in the present work from the analysis
of the broadening profile and pertinent stellar data
table2.dat 103 629 Compilation of all stars measured to date by line
profile analysis and pertinent stellar data
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See also:
J/A+A/398/647 : Rotational velocities of F and G stars (Reiners+ 2003)
J/A+A/412/813 : Rotation in F-stars (Reiners+ 2003)
J/A+A/446/267 : Stellar latitudinal differential rotation (Reiners 2006)
Byte-by-byte Description of file: table?.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Name
20 A1 --- m_Name [A/B] Spectral component (1)
22- 26 F5.2 --- B-V ? B-V colour index (only in table1)
28- 32 I5 K Teff ? Effective Temperature
34- 38 F5.2 mag VMAG ? absolute V magnitude
40- 44 F5.1 km/s vsini Projected rotational velocity
46- 50 F5.1 km/s e_vsini Error on vsini
52- 55 F4.2 --- q2/q1 ? Ratio of second to first Fourier zeroes
57- 60 F4.2 --- e_q2/q1 ? Error of q2/q1
62- 66 F5.2 --- alpha ? Relative differential rotation
α/sqrt(sini) (5)
68 A1 --- f_alpha [-] sign of e_alpha (2)
69- 72 F4.2 --- e_alpha ? Error of alpha (2)
74- 78 F5.1 d P/sini ? Projected rotation period
80- 84 F5.2 rad/d DOmega ? ΔΩsqrt(sini), horizontal shear
(times sqrt(sin.i)) (5)
86- 90 F5.2 rad/d e_DOmega ? Error of DOmega
92-101 A10 --- Flags Flags which characterize the profile (3)
103 I1 --- Ref [1,7]? Source of measurements
(only in table2) (4)
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Note (1): Spectral component: In the case of multiple spectral components,
the strongest component is designated A and the weaker is considered the
B component. These labels are internal to the present work. They do not
necessarily agree with multiplicity indices assessed by other work for the
same targets.
Note (2): In the case of alpha=0 corresponding to rigid rotation, the error
bar gives the maximum value of alpha consistent with the value of q2/q1
measured. This value can be negative in the case of signatures of anti-solar
differential rotation. This case is considered hypothetic since it can be
explained by the presence of a polar spot in the regime of rigid rotation.
Note (3): In the present work, flags introduced by previous work were used as
much as possible and complemented by additional flags, as follows:
d = differential rotator
r = consistent with ΔΩ=0 (rigid rotation)
v = measurement of vsini only
< = upper limit on vsini only
a = asymmetric profile
f = noisy, distorted profile
m2 = multiple with 2 separated components
m3 = multiple with 3 separated components
m? = multiple with unknown number of components
x = photometry affected by unresolved components
y = spectroscopic analysis affected by unresolved components
b = blended multiple (suspected)
s = spotted star (suspected)
c = symmetric profile but candidate for spottedness
The use of flags is neither complete nor fully consistent for the compiled
data set (table2). The flags are rather adopted from the original source of
each entry. The setting of flags follows the policies described there. In
particular, not all differential rotators identified are flagged by 'd'.
In the case of identical flags, their meaning might vary slightly when
using data from different sources.
Note (4): Source of measurements as follows:
1 = this work (CES measurements)
2 = this work (FEROS measurements)
3 = Reiners & Schmitt, 2003, Cat. J/A+A/398/647
4 = Reiners & Schmitt, 2003, Cat. J/A+A/412/813
5 = Reiners & Royer (2004A&A...415..325R 2004A&A...415..325R)
6 = Reiners, 2006, Cat. J/A+A/446/267, table B1
7 = Reiners, 2006, Cat. J/A+A/446/267, table B2
Note (5): The differential rotation at latitude b is described by
Ω(b)=ΩEq(1-αsin2b),
if ΩEq is the equatorial rotation. The horizontal shear is:
ΔΩ=ΩEq-Ωpole=αΩEq
The parameter α of differential rotation is calculated from
the ratio of the zeroes of the Fourier transform q2/q1 using
the modeled relation of q2/q1 and α described in Reiners
and Schmitt (2002A&A...384..155R 2002A&A...384..155R)
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Acknowledgements:
Matthias Ammler-von Eiff, ammler(at)tls-tautenburg.de
(End) M. Ammler-von Eiff [TLS Tautenburg], P. Vannier [CDS] 20-Apr-2012