J/ApJ/725/875 Chromospheric activity for CPS stars (Isaacson+, 2010)
Chromospheric activity and jitter measurements for 2630 stars on the California
Planet Search.
Isaacson H., Fischer D.
<Astrophys. J., 725, 875-885 (2010)>
=2010ApJ...725..875I 2010ApJ...725..875I
ADC_Keywords: Spectroscopy ; Stars, late-type ; Stars, ages
Keywords: stars: activity - stars: chromospheres - stars: fundamental parameters
Abstract:
We present time series measurements of chromospheric activity for more
than 2600 main-sequence and subgiant stars on the California Planet
Search (CPS) program with spectral types ranging from about F5V to M4V
for main-sequence stars and from G0IV to about K5IV for subgiants. The
large data set of more than 44000 spectra allows us to identify an
empirical baseline floor for chromospheric activity as a function of
color and height above the main sequence. We define ΔS as an
excess in emission in the CaII H and K lines above the baseline
activity floor and define radial velocity jitter as a function of
ΔS and B-V for main-sequence and subgiant stars. Although the
jitter for any individual star can always exceed the baseline level,
we find that K dwarfs have the lowest level of jitter. The lack of
correlation between observed jitter and chromospheric activity in K
dwarfs suggests that the observed jitter is dominated by instrumental
or analysis errors and not astrophysical noise sources. Thus, given
the long-term precision for the CPS program, radial velocities are not
correlated with astrophysical noise for chromospherically quiet K
dwarf stars, making these stars particularly well suited for the
highest precision Doppler surveys. Chromospherically quiet F and G
dwarfs and subgiants exhibit higher baseline levels of astrophysical
jitter than K dwarfs. Despite the fact that the rms in Doppler
velocities is correlated with the mean chromospheric activity, it is
rare to see one-to-one correlations between the individual time series
activity and Doppler measurements, diminishing the prospects for
correcting activity-induced velocity variations in F and G dwarfs.
Description:
Here we provide updated activity measurements with a calibration of
SHK (the ratio of flux in the CaII line cores to flux in nearby
continuum regions) to the Mt. Wilson Observatory (MWO) scale for
California Planet Search (CPS) spectra of main-sequence and subgiant
stars obtained after the upgrade of the Keck/HIRES CCD in 2004 August
(resolution R=52000) and activity measurements for stars on the Lick
planet search project.
The Lick Observatory Planet Search began in 1987 with the Hamilton
Spectrometer and both the Shane 3m telescope and the 0.6m Coude
Auxiliary Telescope (CAT) (spectral resolution of R=55000 at 6000Å).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 63 2629 S-values and derived quantities
table2.dat 49 44188 S-values and Julian Date
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See also:
III/159 : Ca II H and K Measurements Made at MWO (Duncan+ 1991)
J/A+A/520/A79 : FGK stars chromospheric activity (Martinez-Arnaiz+, 2010)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/A+A/474/293 : Radial velocities of GJ 674 (Bonfils+, 2007)
J/A+A/469/309 : Chromospheric activity in late-type stars (Cincunegui+, 2007)
J/AJ/123/3356 : Palomar/MSU nearby star spectroscopic survey (Gizis+, 2002)
J/A+AS/142/275 : Stellar-activity of late-type stars (Strassmeier+ 2000)
J/A+AS/146/103 : CaII H+K to CaII IRT echelle spectra (Montes+, 2000)
J/AJ/111/439 : Chromospheric emission in late-type stars. (Henry+ 1996)
http://www.exoplanets.org/cps.html : California Planet Survey home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name (G1)
12- 17 I6 --- HIP ? Hipparcos identification (NNNNN)
19- 23 F5.3 mag B-V Hipparcos catalog (B-V) color index
25- 30 F6.3 --- SHK Median SHK value (G2)
32- 37 F6.3 m/s Jitter [0/80.14] Radial velocity jitter (1)
39- 45 F7.4 [-] logRHK ? Log of R'HK value (G3)
47- 53 F7.2 mag dMag ? Height above the main sequence (δMV)
55- 56 I2 d Prot [0/48]? Rotational period
58- 61 F4.2 Gyr Age [0/8.44]? Age (in Gyr)
63 A1 --- Obs [K/L] Observatory code: (K)eck or (L)ick
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Note (1): We define jitter as the quadrature difference of velocity rms
minus the formal internal errors, equation (6) as below:
Jitter=(rms2-σ2)0.5
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name (G1)
12- 17 I6 --- HIP ? Hipparcos identification (NNNNNA)
19- 27 F9.3 d JD Julian Date of observation (JD-2440000)
29- 34 F6.3 --- SHK ? SHK value (G2)
35 A1 --- f_SHK [N] N: indicates a NaN value
37- 42 F6.3 [-] logRHK ? Log of R'HK value (G3)
43 A1 --- f_logRHK [N] N: indicates a NaN value
45- 47 I3 --- SNR Signal-to-noise ratio
49 A1 --- Obs [K/L] Observatory code: (K)eck or (L)ick
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Global notes:
Note (G1): Star names are HD unless otherwise given. Derived quantities are
only given for stars in the range 4.0<logR'HK←5.1.
Note (G2): Following a method described in Duncan et al. (1991, Cat. III/159),
we measure flux in the core of the CaII H and K lines relative to
continuum bands (SHK). See section 2.1 for Keck SHK calibration
and text for discussion.
Note (G3): To account for different continuum flux levels near the CaII lines
for stars of different spectral type, the SHK values are often
parameterized as log R'HK, a logarithmic fraction of the flux in
the H and K line cores to photometric contributions from the star
(Noyes et al. 1984ApJ...279..763N 1984ApJ...279..763N; Middelkoop 1982A&A...107...31M 1982A&A...107...31M).
Because chromospheric activity declines with stellar age, cluster
stars have been used to calibrate the logR'HK values to the
rotation periods and ages for stars with 0.4<B-V<1.0.
See text for further explanations.
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History:
* 08-Aug-2012: From electronic version of the journal
* 29-Aug-2012: HIP 35821 changed in table 1 and 2 for HIP 57370 where Name
is HD 102195.
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Aug-2012