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J/AJ/111/439 Chromospheric emission in late-type stars. (Henry+ 1996)
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A survey of Ca II H and K chromospheric emission in southern solar-type stars
Henry T.J., Soderblom D.R., Donahue R.A., Baliunas S.L.
<Astron. J. 111, 439 (1996)>
=1996AJ....111..439H
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ADC_Keywords: Stars, atmospheres ; Photometry ; Stars, late-type
Abstract:
More than 800 southern stars within 50pc have been observed for
chromospheric emission in the cores of the Ca II H and K lines. Most
of the sample targets were selected to be G dwarfs on the basis of
colors and spectral types. The bimodal distribution in stellar
activity first noted in a sample of northern stars by Vaughan and
Preston (1980PASP...92..385V) is confirmed, and the percentage of
active stars, about 30%, is remarkably consistent between the northern
and southern surveys. This is especially compelling given that we have
used an entirely different instrumental setup and stellar sample than
used in the previous study. Comparisons to the Sun, a relatively
inactive star, show that most nearby solar-type stars have a similar
activity level, and presumably a similar age. We identify two
additional subsamples of stars -- a very active group, and a very
inactive group. The very active group may be made up of young stars
near the Sun, accounting for only a few percent of the sample, and
appears to be less than ~0.1Gyr old. Included in this high-activity
tail of the distribution, however, is a subset of very close binaries
of the RS CVn or W UMa types. The remaining members of this population
may be undetected close binaries or very young single stars. The very
inactive group of stars, contributing ~5%-10% to the total sample, may
be those caught during a Maunder Minimum type phase. If the
observations of the survey stars are considered to be a sequence of
snapshots of the Sun during its life, we might expect that the Sun
will spend about 10% of the remainder of its main sequence life in a
Maunder Minimum phase.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 125 1016 Chromospheric activity observations
notes.dat 120 79 Notes on individual objects in table 4
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD [1/225300] Henry Draper number
8- 11 A4 --- m_HD Component(s) of HD number
14- 15 A2 --- Note *[0123*] Coded note
18- 26 A9 --- Mult *Multiplicity information
29 A1 --- Ref *[BDGHIJW] Coded reference for Mult
31- 34 A4 --- Sample *[BCNPSX ] Coded sample information
36- 41 F6.3 mag Vmag V magnitude
43- 48 F6.3 mag e_Vmag Error in Vmag
50- 56 F7.3 mag B-V (B-V) color
58- 63 F6.3 mag e_B-V Error in B-V
67- 68 A2 --- MRef *Coded reference for V and B-V
71- 76 A6 --- Date UT date of observation (ddmmyy)
80- 82 A3 --- Flag *Flag indicating special status of obs.
84- 90 F7.3 --- S(CTIO) *? S value from CTIO observation
92- 98 F7.3 --- S(MW) *? S value converted to Mt. Wilson system
100-106 F7.2 --- logR'(HK) *? Log R'(HK) value
111 I1 --- Nobs ? Number of observations
113-119 F7.3 --- logR'(HK)m ? Mean log R' value of observations
121-125 F5.3 --- e_logR'(HK)m ? Error in logR'(HK)m
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Note on Note:
0 = target not listed in INCA (The Hipparcos Input Catalog) <I/196>
1 = double target listed as A and B in INCA, but components
have different HD numbers
2 = target listed as AB in INCA, but split in this survey
3 = target listed as single in INCA, but with orbits in references
B, D or G (see Ref below)
* = note given in file notes.dat
Note on Mult:
Multiplicity information
P = period in d(ays) or y(ears)
s = separation in arcseconds
a = semimajor axis of orbit in arcseconds
Note on Ref:
Reference for multiplicity information
B = Batten, Fletcher & MacCarthy 1989, Eighth Catalogue of the
Orbital Elements of Spectroscopic Binary Systems, <V/64>
D = Duquennoy & Mayor (1991A&A...248..485D)
G = Gliese (1969VeARI..22....1G) (G69);
Gliese & Jahreiss 1979, (1979A&AS...38..423G); 1991,
Preliminary Version of the Third Catalog of Nearby Stars (GJ91) <V/70>
H = Heintz (1984AJ.....89.1068H); (1994AJ....108.2338H)
I = Hipparcos Input Catalog, Turon, C. et al. 1992, (INCA) <I/196>
J = Jeffers, van den Bos & Greeby 1963, Index Catalogue of Visual
Double Stars, 1961.0, Publications of the Lick Observatory,
v. XXI (IDS). See WDS <I/107>
W = Worley & Heintz 1983, Fourth Catalog of Orbits of Visual Binary
Stars, <V/39> (WH83)
Note on Sample:
B = Best & Brightest
C = Calibration
N = Nearby
P = Primary
S = Secondary
X = Extra
Note on MRef:
Reference for magnitude and color information
Ig = INCA, good data with (B-V) error <= 0.10 mag
Ip = INCA, poor data with (B-V) error > 0.10 mag, only value available
G = Gliese & Jahreiss 1991 <V/70>
S = SIMBAD <http://cdsweb.u-strasbg.fr/Simbad.html>
blank = no value available
Note on Flag:
Flag indicating special status of observation
cal = calibration star
con = contaminated spectrum
hgh = very high SCTIO value (>0.600)
low = very low SCTIO value (<0.180)
noi = noisy spectrum
off = minima of H and K lines out of dithering window
pht = no (B-V) photometry available, or (B-V) out of sample range
(0.50 to 1.00 for all samples)
There are only 4 stars with (B-V)=0.40 to 0.49: 1 Primary,
1 Calibration, 2 Extra targets.
ray = cosmic ray in necessary window
spc = special target
str = strange spectrum
Note on S(CTIO) and S(MW):
S is the flux index for the Ca II H and K lines
Note on logR'(HK):
R'(HK) is the ratio of the emission from the chromosphere in the cores of the
Ca II H and K lines to the total bolometric emission of the star. The prime
denotes the substraction of a photospheric contribution to the observed
H and K emission.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD Star
8 I1 --- seq ? Line number when the note consists
of several lines
10-120 A111 --- Text Text of note
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Origin: AAS CD-ROM series, Volume 6, 1996 Lee Brotzman [ADS] 07-Mar-1996
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(End) [CDS] 05-Sep-1996