CDROM/AJ/V111/P0439
Chromospheric Emission (Henry+ 1996)
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A Survey of Ca II H and K Chromospheric Emission in Southern Solar-Type
Stars
Todd J. Henry, David R. Soderblom, Robert A. Donahue and
Sallie L. Baliunas
<1996, AJ, 111, 439>
=1996AJ....111..439H
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Abstract:
More than 800 southern stars within 50 pc 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 in 1980 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 ~0.1 Gyr 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:
------------------------------------------------------------------------------File Name
Lrecl
Records
Explanations
------------------------------------------------------------------------------table4.dat
125
1016
Chromospheric activity observations
table4.not
70
177
Notes on individual objects in table 4
------------------------------------------------------------------------------Byte-by-byte Description of file: table1.dat
------------------------------------------------------------------------------Bytes Format Units
Label
Explanations
------------------------------------------------------------------------------1-11
A11
--HD
Henry Draper number
12-13
2X
----Blank
14-15
A2
--Note
*[0123*] Coded note
16-17
2X
----Blank
18-26
A9
--Mult
*Multiplicity information
27-28
2X
----Blank
29
A1
--Ref
*[BDGHIJW] Coded reference for Mult
30
1X
----Blank
31-34
A4
--Sample
*[BCNPSX] Coded sample information
35-41
F7.3
mag
V
V magnitude
42-48
F7.3
mag
e_V
Error in V
49-56
F8.3
mag
B-V
(B-V) color
57-63
F7.3
mag
e_B-V
Error in B-V
64-66
3X
----Blank
67-68
A2
--MRef
*Coded reference for V and B-V
69-70
2X
----Blank
71-76
A6
--Date
UT date of observation
77-79
3X
----Blank
80-82
A3
--Flag
*Flag indicating special status of
obs.
83-90
F8.3
--SCTIO
[]? S value from CTIO observation
91-98
F8.3
--SMW
[]? S value converted to Mt. Wilson
system
99-106 F8.2
--RHK
[]? Log R'(HK) value
107-110 4X
----Blank
111
I1
--Obs
[]? Number of observations
112-119 F8.3
--MRHK
[]? Mean log R' value of observations
120-125 F6.3
--e_MRHK
[]? Error in MRHK
------------------------------------------------------------------------------Notes for file: table4.dat
------------------------------------------------------------------------------Notes:
0 = target not listed in INCA (The Hipparcos Input Catalog)
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 at end of table
Mult:
Multiplicity information
P = period in d(ays) or y(ears)
s = separation in arcseconds
a = semimajor axis of orbit in arcseconds
Ref:
Reference for multiplicity information
B = Batten, Fletcher & MacCarthy 1989, Eighth Catalogue of the
D =
G =
H =
I =
J =
W =
Orbital Elements of Spectroscopic Binary Systems, Publications
of the Dominion Astrophysical Observatory, v. XVII (BFM89)
Duquennoy & Mayor 1991, A&A, 248, 485
Gliese 1969, Veroffentlichungen des Astronomischen RechenInstituts, Heidelburg, No. 22 (G69); Gliese & Jahreiss 1979,
A&AS, 38, 423; 1991, Preliminary Version of the Third Catalog
of Nearby Stars (GJ91)
Heintz 1984, AJ, 89, 1068; 1994, AJ, 108, 2338
Hipparcos Input Catalog, Turon, C. et al. 1992, ESA Publication
Division, c/o ESTEC, Noordwijk, The Netherlands (INCA)
Jeffers, van den Bos & Greeby 1963, Index Catalogue of Visual
Double Stars, 1961.0, Publications of the Lick Observatory,
v. XXI (IDS)
Worley & Heintz 1983, Fourth Catalog of Orbits of Visual Binary
Stars, Publications of the United States Naval Observatory,
v. XXIV, part VII (WH83)
Sample:
B = Best & Brightest
C = Calibration
N = Nearby
P = Primary
S = Secondary
X = Extra
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
S = SIMBAD
blank = no value available
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
------------------------------------------------------------------------------Byte-by-byte Description of file: table4.not
------------------------------------------------------------------------------Bytes Format Units
Label
Explanations
------------------------------------------------------------------------------1-70
A70
--Note
HD number followed by text of the
note
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(End)
Lee Brotzman [ADS] 07Mar-1996