J/AJ/168/240 Equivalent widths, Li & activity for solar analogs (Lubin+, 2024)
Hamilton Echelle Spectrograph observations of solar analog field stars: lithium
abundance and activity.
Lubin D., Holden B.P., Stock C., Melis C., Tytler D.
<Astron. J., 168, 240 (2024)>
=2024AJ....168..240L 2024AJ....168..240L
ADC_Keywords: Spectra, optical ; Stars, G-type ; Rotational velocities ;
Equivalent widths ; Abundances
Keywords: Stellar activity
Abstract:
We measured lithium (Li) abundance and instantaneous chromospheric
CaII HK activity in Hamilton Echelle Spectrograph observations of
211 solar analog field stars, with one objective being potential
identification of grand minimum candidates for ongoing multiyear
observation. At the zero-age main sequence, Li abundance for a typical
late-type dwarf begins at the local interstellar medium abundance and
over the main sequence lifetime is steadily depleted by convection at
a rate dependent on details of the star's convection and mixing
processes. Our Li abundance measurements show an overall decrease in
Li abundance with age and effective temperature, consistent with
earlier surveys. In our activity measurements, 41 stars show
logR'HK≤-5.0, which can be considered very inactive. Of the very
inactive stars closest to solar effective temperature, 24 show Li
abundances within the range typically observed for midlife Sun-like
stars. Another three show very low Li abundance, which, combined with
the low activity, suggest an older main sequence star or a slightly
evolved star. We suggest that the combination of relatively undepleted
Li and instantaneous very low activity might make these stars
promising candidates for long time-series observations to determine if
they are in a grand minimum state. The Hamilton Echelle Spectrograph
observations are publicly available for download and are potentially
useful for a variety of survey tasks involving Sun-like stars.
Description:
Our criteria for selecting solar analogs include: (1) effective
temperature within ±500K of solar; (2) -0.3≤[Fe/H]≤+0.3;
and (3) absolute magnitude MV within ±0.5 of the Hipparcos main
sequence (Wright 2004, 2004AJ....128.1273W 2004AJ....128.1273W). We can identify more than
seven hundred stars meeting these criteria. An additional selection
criterion is that a star have no indication in the SIMBAD Astronomical
Database of being part of a double or multiple system, or being a
chromospherically active variable, such as type RS CVn or BY Dra.
Over 22 nights with the Hamilton Echelle Spectrograph (R=60,000) on
the optical Shane 3m telescope, located at the Lick Observatory in
San Jose, California, we observed 211 solar analogs (mV<9.2) between
2013 February and 2014 January.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 67 211 Observational results for the 211 program stars
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See also:
III/159 : Ca II H and K Measurements Made at MWO (Duncan+ 1991)
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
V/130 : Geneva-Copenhagen Survey of Solar neighbourhood III (Holmberg+, 2009)
J/AJ/106/1059 : Lithium in the Pleiades (Soderblom+, 1993)
J/AJ/111/439 : Chromospheric emission in late-type stars. (Henry+ 1996)
J/ApJS/152/261 : Chromospheric Ca II emission in nearby stars (Wright+, 2004)
J/ApJS/159/141 : Spectroscopic properties of cool stars. I. (Valenti+, 2005)
J/A+A/468/663 : Li abundances in solar-analog stars (Takeda+, 2007)
J/AJ/133/2524 : Spectra of young nearby stars (White+, 2007)
J/A+A/484/815 : Scaled solar tracks and isochrones (Bertelli+, 2008)
J/A+A/508/355 : Scaled solar tracks and isochrones (Bertelli+, 2009)
J/A+A/501/687 : Evolutionary models for solar twins (do Nascimento+, 2009)
J/AJ/138/312 : Activity of bright solar analogs (Hall+, 2009)
J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)
J/A+A/530/A138 : Geneva-Copenhagen survey re-analysis (Casagrande+, 2011)
J/A+A/545/A55 : Extrasolar planets. RVs of 5 stars (Boisse+, 2012)
J/ApJ/749/15 : The Kepler-20 planetary system (Gautier+, 2012)
J/ApJ/756/46 : Lithium abundances in HIP stars (Ramirez+, 2012)
J/ApJ/763/L26 : SMARTS observations of eps Eridani (Metcalfe+, 2013)
J/AJ/146/97 : Ti line list for Lick hallow-cathode lamp (Pakhomov+, 2013)
J/ApJ/831/116 : Phot. & spectroscopy of PMS stars in NGC 2264 (Lim+, 2016)
J/ApJ/817/104 : Keck/HIRES radial velocity obs. of HD32963 (Rowan+, 2016)
J/ApJ/920/100 : Reconstruction of solar irradiance: 1700 to 2019 (Wang+, 2021)
J/AJ/163/183 : S-value for 59 Sun-like stars with HIRES and HKP (Baum+, 2022)
J/ApJ/936/L23 : T4 APT photometry of HD 166620 (Luhn+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD [804/224465] HD identifier
8- 17 A10 "Y/M/D" Date Date of Lick observation (1)
19- 23 F5.2 Gyr ageEP [1.24/10.1] Expectation age from
Casagrande+ 2015, J/A+A/530/A138
25- 29 F5.3 --- S [0.13/0.59] S units (2)
31- 35 F5.2 --- logRHK [-5.2/-4.1] Log(R'HK) activity index (3)
37- 41 F5.1 0.1pm EWLi [3.8/118]? Equivalent width of Li 6708Å line,
Wλ(Li) in mÅ
43 A1 --- l_logNLi Upper limit flag on logNli
45- 48 F4.2 --- logNLi [0.4/3] Li abundance as Log(NLi)
50- 53 F4.1 0.1pm EWbl [0/15]? Equivalent width of the blended line
near Li 6708Å line, Wλ(BL) in mÅ
55- 58 F4.1 0.1pm EWFeI [20/54] Equivalent width of FeI 6703Å line,
Wλ(FeI) in mÅ
60- 64 F5.1 0.1pm EWCaI [89/161] Equivalent width of CaI 6717Å line,
Wλ(CaI) in mÅ
66- 67 I2 km/s vsini [1/16] Projected rotational velocity v.sin(i)
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Note (1): Activities, equivalent widths Wλ, Li abundances, and
projected rotational velocities are measured from the Lick
observation on the date given.
Note (2): First L units are defined in Wright+ 2004 (J/ApJS/152/261) as:
L=H/C
where H is the relative flux measured at the core of the CaII H
feature (3968.47Å) using a triangular bandpass of full width half
maximum 1.0Å, and C is the flux integrated over a small continuum
region at slightly longer wavelengths.
Then S units are found through a linear regression of the L units
against the corresponding Isaacson+ 2010 (J/ApJ/725/875) S units:
S=4.5662L+0.016498
See Section 3.
Note (3): S values are transformed to log(R'HK) by removing the photospheric
component, as described in Henry+ 1996 (J/AJ/111/439),
Wright+ 2004 (J/ApJS/152/261), and references therein.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 01-Jul-2025