J/PASP/111/335 CaII-Mv Correlation (Wilson-Bappu Effect) (Wallerstein+ 1999)
The Ca II-Mv Correlation (Wilson-Bappu Effect) Calibrated by Hipparcos
Parallaxes
Wallerstein G., Machado-Palaez L., Gonzalez G.
<Publ. Astron. Soc. Pac. 111, 335 (1999)>
=1999PASP..111..335W 1999PASP..111..335W
ADC_Keywords: Parallaxes, trigonometric; Magnitudes, absolute;
Photometry, K-line; Stars, late-type
Description:
Hipparcos parallaxes were used to derive absolute visual magnitudes of
G, K, and M stars with Ca II emission line widths previously measured
by O.C. Wilson. A linear relationship similar to the one derived
originally by Wilson & Bappu and improved by Lutz & Kelker was found
from Mv=+7 to -2. For stars brighter than Mv=-2 a substantial
number of stars show Ca II emission lines that are broader than
expected from the linear fit. Most of those stars are bright giants
and supergiants of type G.
Introduction:
In 1957 O. C. Wilson and M. K. V. Bappu reported on the remarkable
correlation between the measured width of the emission feature at the
center of the Ca II K line and the absolute visual magnitude of the
star. The correlation is independent of spectral type and applicable
to stars of type G, K, and M. Their original calibration was based on
the Sun and the four K giants in the Hyades. Except for the
main-sequence stars there were not many additional calibrating stars
with sufficiently accurate parallaxes to evaluate the dispersion about
the mean relation or to extend the calibration to stars brighter than
about Mv = 0.
The paucity of accurate parallaxes for luminous red giants has been
largely overcome by the Hipparcos program (Kovalevsky
1998ARA&A..36...99K 1998ARA&A..36...99K) in which parallaxes with uncertainties of near 1
mas were obtained for numerous stars. Hence, we now have 10 sigma
parallaxes out to 100 pc and 5 sigma data to 200 pc, providing
Mv-values with uncertainties of 0.21 and 0.42 mag, respectively.
Therefore, the large database provided by Wilson (1976ApJ...205..823W 1976ApJ...205..823W)
can be combined with Hipparcos parallaxes to recalibrate the Mv -
log W0 relation, where W0 is the measured width corrected for the
instrumental width. In addition, stars that appear to deviate from the
Wilson-Bappu relation may be investigated in order to understand the
anomalies of their chromospheres.
We have limited ourselves to stars with parallaxes that are at least 5
times their probable error and whose log W0-values are listed by
Wilson (1967PASP...79...46W 1967PASP...79...46W, 1976ApJ...205..823W 1976ApJ...205..823W). Other databases are
available, e.g., Warner (1967MNRAS.137..119W 1967MNRAS.137..119W) and Zarro & Rogers
(1983ApJS...53..815Z 1983ApJS...53..815Z), but the Wilson data are so much larger than the
others that we decided to base our discussion on these data alone. For
each star we have extracted the parallax, its probable error, V
magnitude, spectral type, B-V color, and V-I color from the Hipparcos
Catalogue (ESA 1997, Cat. I/239). These quantities are listed in
Table 1 along with Wilson's intensity index (1-5), log W0, and the
Mv-value derived from the apparent magnitude and parallax.
Table 1 is divided into three sections: Table1a.dat contains stars
with Ca II emission index 2 from Wilson (1976ApJ...205..823W 1976ApJ...205..823W);
Table1b.dat contains stars of index 1 from the same source; and
Table1c.dat contains stars in Wilson (1967PASP...79...46W 1967PASP...79...46W). The
complete data set has been used to plot fig1.gif, where we show Mv
plotted against log W0, the same coordinates used by Wilson & Bappu
(1957ApJ...126...46W 1957ApJ...126...46W). Because of the crowding we do not show the
probable errors of each point in this plot.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1a.dat 54 390 Stars with Ca II Emission of Intensity Index
≥2 and Hipparcos Parallaxes (Wilson 1976)
table1b.dat 53 250 Stars with Ca II Emission of Intensity Index
1 and Hipparcos Parallaxes (Wilson 1976)
table1c.dat 53 30 Mostly Lower Luminosity Stars with Ca II
Emission and Hipparcos Parallaxes
(Wilson 1967)
fig1.gif 1 65587 *695 x 639 GIF image of Dependence of Mv as
derived from Hipparcos parallaxes on log W0
fig2.gif 1 49152 695 x 639 GIF image of Dependence of the
deviation from the mean line, delta log W0,
on Wilson's estimated intensity of Ca II
emission
fig3.gif 1 51575 695 x 639 GIF image of Dependence of delta log
W0 on spectral type
fig4.gif 1 102442 653 x 853 GIF image of Sample profiles of the
Ca II K line. Note the apparent emission
features at 3936.0 and 3938.3 angstroms due
to Fe II in some stars
fig5.gif 1 109958 653 x 853 GIF image of Sample profiles of the
Ca II H line and Hepsilon
--------------------------------------------------------------------------------
Note on fig1.gif:
An unweighted least-squares fit to the data is shown as a solid line.
The dashed line shows a least-squares fit with the points weighted by
parallax/probable error. Circles represent stars with parallax >
(10xprobable error); triangles represent stars with (10xprobable
error) > parallax > (5xprobable error). Stars within the parallelogram
are described in Table 2. The symbols have the same meaning in
fig2.gif and fig3.gif.
--------------------------------------------------------------------------------
Table 2
Stars within the Box in fig1.gif
-----------------------------------------------
Star (HD) Spectral Type log W0 Mv Trig.
-----------------------------------------------
16901 G0 Ib 2.15 -1.20
20123 G5 III 2.10 -2.00
26630 G0 Ib 2.15 -2.61
74395 G1 Ib 2.12 -1.71
92125 G3 Ib-II 2.07 -1.13
159181 G2 II 2.19 -2.43
173764 G4 II 2.11 -2.41
204075 G4 Ibp* 2.07 -1.66
204867 G0 Ib 2.16 -3.47
209750 G2 Ib 2.20 -3.88
210745 K1 Ib 2.16 -3.35
222574 G0 Ib 2.09 -1.65
-----------------------------------------------
* A well-known Ba II star.
Table A1
Properties of Stars Whose Spectra are Displayed in fig4.gif and fig5.gif
------------------------------------------------------------------------
Spectral
Region Spectral
Star (angstroms) Type Mv log W0 Observatory
------------------------------------------------------------------------
Boo 3933,68 K2 IIIp -0.31 1.83 DAO
UMa 3933,68 K0 III -1.08 1.84 DAO
Leo A 3933 K1 III -0.92 1.82 DAO
Dra 3968 K2 +0.81 1.75 DAO
Vir 3968 M1 III -0.87 1.86 McD
Cyg 3933,68 K5 Ib-II -4.07 1.83 McD
Aqr 3933,68 G2 Ib -3.88 2.20 McD
56 Leo 3933 M5 II +0.92 1.93 McD
------------------------------------------------------------------------
Table A2
Measured Wavelengths of Suspected Emission Lines Other than the
Ca II, H and K Lines
-----------------------------------------------------------
Star HD H 3970.05 Fe II 3935.94 Fe II 3938.27
-----------------------------------------------------------
89484** 69.90 37.81
94705* 71.63 35.96
95689** 70.11 37.82
102212* 70.38 35.94
121299* 70.47
124897* 70.14
124897** 70.18 35.80 37.88
133165* 69.73 35.55
137759** 69.99
200905* 69.31 35.60 37.75
209750* 35.70 38.20
-----------------------------------------------------------
* Spectrum obtained at Dominion Astrophysical Observatory.
** Spectrum obtained at McDonald Observatory.
Byte-by-byte Description of file: table1a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HD HD number
8- 12 F5.2 mas plx Trigonometric Parallax
14- 17 F4.2 mas e_plx Parallax probable error
19- 21 F3.1 mag Vmag V magnitude
23- 31 A9 --- SpType Spectral Type
33- 36 F4.2 mag B-V B-V color
38- 41 F4.2 mag V-I V-I color
43 I1 --- Int_idx [2-5] Intensity index
45- 48 F4.2 --- logW log W0
50- 54 F5.2 mag Mv Mv-value derived from the apparent
magnitude and parallax
--------------------------------------------------------------------------------
See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
Byte-by-byte Description of file: table1b.dat, table1c.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HD HD number
8- 13 F6.2 mas plx Trigonometric Parallax
15- 18 F4.2 mas e_plx Parallax probable error
20- 22 F3.1 mag Vmag V magnitude
24- 32 A9 --- SpType Spectral Type
34- 37 F4.2 mag B-V B-V color
39- 42 F4.2 mag V-I V-I color
44- 47 F4.2 --- logW log W0
49- 53 F5.2 mag Mv Mv-value derived from the apparent
magnitude and parallax
--------------------------------------------------------------------------------
Acknowledgements:
Dr. George Wallerstein
Department of Astronomy
University of Washington
Seattle, WA 98195
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(End) Gail L. Schneider [SSDOO/ADC] 18-Jul-1999