J/A+A/520/A79 Nearby FGK stars chromospheric activity (Martinez-Arnaiz+, 2010)
Chromospheric activity and rotation of FGK stars in the solar vicinity.
An estimation of the radial velocity jitter.
Martinez-Arnaiz R., Maldonado J., Montes D., Eiroa C., Montesinos B.
<Astron. Astrophys. 520, A79 (2010)>
=2010A&A...520A..79M 2010A&A...520A..79M
ADC_Keywords: Stars, late-type ; Radial velocities ; Rotational velocities ;
Equivalent widths
Keywords: solar neighbourhood - stars: late-type - stars: activity -
stars: chromospheres - stars: rotation - stars: planetary systems
Abstract:
Chromospheric activity produces both photometric and spectroscopic
variations that can be mistaken as planets. Large spots crossing the
stellar disc can produce planet-like periodic variations in the light
curve of a star. Moreover, spots clearly affect the spectral line
profiles. Such perturbations will in turn affect the line centroids
creating a radial velocity jitter that might "contaminate" the
variations induced by a planet. Precise chromospheric activity
measurements are needed to estimate the activity-induced noise
that should be expected for a given star.
The purpose of this paper is to obtain precise chromospheric activity
measurements and projected rotational velocities for nearby (d<25pc)
cool (spectral types F to K) stars, in order to estimate the
activity-related jitter that should be expected for them. As a
complementary objective, in this paper we aim to obtain relationships
between fluxes in different activity indicator lines, which will
permit a transformation of traditional activity indicators, i.e,
CaII H & K lines, to other which hold noteworthy advantages.
We used high resolution (∼50000) echelle optical spectra. Standard
data reduction was performed using the IRAF echelle package. To reveal
the chromospheric emission of the stars in the sample we used the
spectral subtraction technique. We measured equivalent widths of the
chromospheric emission lines in the subtracted spectrum and
transformed them into fluxes by applying empirical equivalent
width-flux relationships. Rotational velocities were determined using
the cross-correlation technique. To infer activity-related radial
velocity (RV) jitter we used empirical relationships between this and
the R'HK index.
We have measured chromospheric activity, as given by different
indicators throughout the optical spectra, and projected rotational
velocities for 371 nearby cool stars. We have built empirical
relationships among the most important chromospheric emission lines.
Finally, we have used the measured chromospheric activity to estimate
the expected RV jitter for the active stars in the sample.
Description:
Rotation, excess chromospheric emission (equivalent widths and fluxes)
and estimated radial velocity jitter for 371 F, G and K stars in the
solar vicinity (d<25pc).
File Summary:
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FileName Lrecl Records Explanations
-----------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 88 423 Stellar parameters of the stars
tablea2.dat 98 182 Excess emission (equivalent widths)
tablea3.dat 92 182 Excess emission (Flux) & logR'HK
tablea4.dat 56 181 Estimated radial velocity jitter
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See also:
J/A+A/331/581 : Rotation and activity in field M dwarfs (Delfosse+ 1998)
J/A+A/469/309 : Chromospheric activity in late-type stars (Cincunegui+, 2007)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP HIP number of the star
8- 9 A2 --- n_HIP [+* ] Notes (1)
11- 18 A8 --- Spect Spectrograph used
20- 29 F10.4 d MJD Modified Julian Date
31- 32 I2 h RAh Right ascension (J2000.0)
34- 35 I2 min RAm Right ascension (J2000.0)
37- 41 F5.2 s RAs Right ascension (J2000.0)
43 A1 --- DE- Declination sign (J2000)
44- 45 I2 deg DEd Declination (J2000)
47- 48 I2 arcmin DEm Declination (J2000)
50- 53 F4.1 arcsec DEs Declination (J2000)
55- 59 F5.3 mag B-V B-V colour index
61- 69 A9 --- SpType MK spectral type
71- 72 A2 --- l_vsini [≥ ] Limit flag on vsini
73- 77 F5.2 km/s vsini ?=- Projected rotational velocities
79- 88 A10 --- Activ Activity of the star
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Note (1): Notes as follows:
+ = stars with known exoplanets
* = stars with chromospheric variation during our observations
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP HIP number of the star
8- 15 A8 --- Spect Spectrograph used
17- 26 F10.4 d MJD Modified Julian Date of observation
28- 32 F5.3 0.1nm W(K) ?=- CaII K excess emission equivalent width
34- 38 F5.3 0.1nm e_W(K) ? Error in W(K)
40- 44 F5.3 0.1nm W(H) ?=- CaII H excess emission equivalent width
46- 50 F5.3 0.1nm e_W(H) ? Error in W(H)
52- 56 F5.3 0.1nm W(Ha) ?=- Hα excess emission equivalent width
58- 62 F5.3 0.1nm e_W(Ha) ? Error in W(Hα)
64- 68 F5.3 0.1nm W(IRT1) ?=- CaII IRT1 excess emission equivalent width
70- 74 F5.3 0.1nm e_W(IRT1) ? Error in W(IRT1)
76- 80 F5.3 0.1nm W(IRT2) ?=- CaII IRT2 excess emission equivalent width
82- 86 F5.3 0.1nm e_W(IRT2) ? Error in W(IRT2)
88- 92 F5.3 0.1nm W(IRT3) ?=- CaII IRT3 excess emission equivalent width
94- 98 F5.3 0.1nm e_W(IRT3) ? Error in W(IRT3)
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP HIP number of the star
8- 15 A8 --- Spect Spectrograph used
17- 26 F10.4 d MJD Modified Julian Date of observation
28- 32 F5.3 [mW/m2] F(K) ?=- CaII K excess emission flux (log)
33- 37 F5.3 [mW/m2] e_F(K) ? Error logF(K)
38- 42 F5.3 [mW/m2] F(H) ?=- CaII H excess emission flux (log)
43- 47 F5.3 [mW/m2] e_F(H) ? Error logF(H)
48- 52 F5.3 [mW/m2] F(Ha) ?=- Hα excess emission flux (log)
53- 57 F5.3 [mW/m2] e_F(Ha) ? Error logF(Hα)
58- 62 F5.3 [mW/m2] F(IRT1) ?=- CaII IRT1 excess emission flux (log)
63- 67 F5.3 [mW/m2] e_F(IRT1) ? Error logF(IRT1)
68- 72 F5.3 [mW/m2] F(IRT2) ?=- CaII IRT2 excess emission flux (log)
73- 77 F5.3 [mW/m2] e_F(IRT2) ? Error logF(IRT2)
78- 82 F5.3 [mW/m2] F(IRT3) ?=- CaII IRT3 excess emission flux (log)
83- 87 F5.3 [mW/m2] e_F(IRT3) ? Error logF(IRT3)
88- 92 F5.2 --- log(R'HK) ?=- Activity index derived from the
CaII H+K lines
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP HIP number of the star
8 A1 --- f_HIP [d] d for stars with log(R'HK)←4.9
10- 17 A8 --- Spect Spectrograph used
19- 28 F10.4 d MJD Modified Julian Date
30- 35 A6 --- SpType MK spectral type
39- 43 F5.2 --- log(R'HK) Activity index derived from CaII H+K lines
45- 46 I2 m/s sigRV1.l Lower value of estimated RV jitter from
Saar et al., 1998ApJ...498L.153S 1998ApJ...498L.153S
47 A1 --- --- [-]
48- 50 I3 m/s sigRV1.u Upper value of estimated RV jitter from
Saar et al., 1998ApJ...498L.153S 1998ApJ...498L.153S
52- 53 I2 m/s sigRV2.l Lower value of estimated RV jitter from
Santos et al., 2000A&A...361..265S 2000A&A...361..265S
54 A1 --- --- [-]
55- 56 I2 m/s sigRV2.u Upper value of estimated RV jitter from
Santos et al., 2000A&A...361..265S 2000A&A...361..265S
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Acknowledgements:
Raquel Martinez-Arnaiz, rma(at)astrax.fis.ucm.es
(End) Patricia Vannier [CDS] 04-Feb-2010