J/AJ/106/1059 Lithium in the Pleiades (Soderblom+, 1993)
The evolution of the lithium abundances of solar-type stars. III. The Pleiades
Soderblom D.R., Jones B.F., Balachandran S., Stauffer J.R.,
Duncan D.K., Fedele S.B., Hudon J.D.
<Astron. J. 106, 1059 (1993)>
=1993AJ....106.1059S 1993AJ....106.1059S (SIMBAD/NED Reference)
ADC_Keywords: Abundances ; Clusters, open
Abstract:
We report new measurements of lithium in more than 100 Pleiades F, G,
and K dwarfs. Abundances were determined from spectrum synthesis fits
to the data as well as from use of new curves of growth for the
Li 6708 A feature (presented in an Appendix). We confirm the intrinsic
spread in lithium abundance within the Pleiades seen by Duncan & Jones
(1983ApJ...271..663D 1983ApJ...271..663D), but we establish more observational constraints
on Li in this cluster: First, for stars near 1.0Msun [about 0.60 to
0.75 in (B-V)0], the scatter in the relation between log N(Li) (defined
as N(Li)) and T(eff) is consistent with our observational uncertainty.
That means that most late-F and early-G dwarfs in the Pleiades are
consistent with the tight N(Li) versus mass relation seen in the Hyades
in the same mass range. Second, at (B-V)0∼0.8 (M∼0.9Msun), large and
real star-to-star differences in N(Li) appear. The range in N(Li) at
(B-V)0∼0.8 is about 1dex, and grows to as much as 1.5dex for less massive
stars. Third, the most Li-rich stars have abundances at or near the
primordial level for Population I (N(Li)∼3.2), and none exceed that
level by a significant amount. Fourth, at any given color the stars that
rotate fastest have the most Li and have the strongest chromospheric
activity. We consider the ways in which an apparent spread in N(Li)
could arise from an intrinsically tight N(Li)-mass relation and conclude
that the spread is probably real and is not an artifact of line formation
conditions or inhomogeneous atmospheres on the stars. It is possible to
produce large apparent changes in N(Li) by covering a significant fraction
of a star's surface with cooler regions ("spots"), but doing so has other
ramifications that conflict with the observations. Some current models lead
to a spread in N(Li) in which the fastest rotators (those that have lost
the least angular momentum) have the most Li, and that mechanism may
account for what is seen. A comparison of the Pleiades to the Alpha
Persei cluster shows that most Alpha Persei stars have Li abundances
comparable to their Pleiades counterparts, but there is a significant
fraction (about 30%) of Alpha Persei stars that lie below the Pleiades
in N(Li) by 1dex or more. Some of these anomalous stars have even
less Li than Hyades stars of the same T(eff). If these stars are bona
fide Alpha Persei members (and they probably are), their Li abundances
strain our understanding of Li depletion. The Pleiades, considered
together with Alpha Persei and the Hyades, shows that stars with
[Fe/H]≥0.0 and which are more massive than about 1.25Msun do not
deplete Li prior to reaching main the sequence. Moreover, solar-abundance
stars ([Fe/H]∼0.0) with M≳1.1Msun do not experience pre-main-sequence
depletion either. Pleiades dwarfs near T(eff)=6700K show evidence of being
depleted in Li, indicating that an incipient Li "chasm" is present even at
an age of 70Myr.
File Summary:
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File Name Lrecl Records Explanations
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ReadMe 80 . This file
table1 79 131 Observations of Lithium in Pleiades F, G,
and K dwarfs
table2 85 61 *Lithium abundances for the 6708 A feature
table3 85 51 *Lithium abundances for the 6104 A feature
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Note on table2, table3: A grid of curves of growth was computed for every
250K in T(eff) from 4000 to 6500K, and for every 0.2dex in logN(Li).
A microturbulent velocity of 1.0km/s was used for the tables given
here, but computations for Xi=2km/s differ little. One dimensional
interpolation was done to create points evenly spaced in log W(lambda)
with log N(Li) as the dependent variable.
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 4 A4 --- fgk fgk number from Soderblom et al.
(1993ApJS...85..315S 1993ApJS...85..315S) (hereafter SSHJ)
6- 9 A4 --- name Hertzsprung (H II) designation.
A "P" prefix denotes a Pels star.
11- 16 A6 --- Sp Spectral type
17- 21 F5.3 mag (B-V)0 Dereddened (B-V)
22 A1 --- u_(B-V)0 Uncertainty flag on (B-V)0
24- 27 I4 K Teff Effective temperature
29 A1 --- l_vsini Limit flag on vsini
30- 34 F5.1 km/s vsini ? Rotational velocity
35 A1 --- u_vsini uncertainty flag on vsini
36 A1 --- n_vsini [S ] 'S' indicating a double-lined
spectroscopic binary whose vsini values are
given in table2 of SSHJ (SB2).
38- 42 F5.2 --- log(RHalpha) []? Ratio of the Halpha flux to the stellar
bolometric flux, log R(Halpha) from SSHJ
44- 48 F5.2 --- log(R8542) []? Ratio of the 8542 A Ca II line flux to the
stellar bolometric flux, logR(8542) from SSHJ
51- 53 I3 0.1pm W7699 []? Equivalent width of K I 7699A line
56- 58 I3 0.1pm W6717 []? Equivalent width of Ca I 6717 A line
59 A1 --- n_W6717 Note on W6717. See note (1)
60 A1 --- l_W6708 Limit flag on W6708
61- 63 I3 0.1pm W6708 Equivalent width of Li I 6708 A line,
corrected for Fe I 6707.441.
64 A1 --- u_W6708 Uncertainty flag on W6708
65 A1 --- n_W6708 Note on W6708. See note (1)
67- 72 A6 --- q Source and quality code (2)
73 A1 --- l_log(N(Li)) Limiting character for lithium abundance
75- 78 F4.2 --- log(N(Li)) Abundance of lithium (scale logN(H)=12)
79 A1 --- u_log(N(Li)) Uncertainty flag on log(N(Li))
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Note (1): A '*' indicates that equivalent width of the line has been
compensated for spectrum dilution by the following factors:
H II 102, 1.33; H II 173, 1.40; H II 248 and 2147, 1.20;
H II 298, 571, 1100, and 2406, 1.10; H II 320, 1.15; H II 1101, 1.25.
Note (2): Source and quality code:
Bo = Boesgaard et al. 1988b, =1988ApJ...327..389B 1988ApJ...327..389B
Bu = Butler et al. 1987, =1987ApJ...319L..19B 1987ApJ...319L..19B
P = Pilachowski et al. 1987, =1987PASP...99.1288P 1987PASP...99.1288P
Codes a to d denote Lick data and are in descending order of quality,
with approximate uncertainties of 12, 18, 25, and 40 mA, respectively
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Byte-by-byte Description of file: table2 table3
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Bytes Format Units Label Explanations
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4- 7 F4.2 [0.1pm] log(W6708) Equivalent width of Li 6708 line
10- 15 F6.3 --- logN(Li)1 Li abundance for Teff = 4000 K
17- 22 F6.3 --- logN(Li)2 Li abundance for Teff = 4250 K
24- 29 F6.3 --- logN(Li)3 Li abundance for Teff = 4500 K
31- 36 F6.3 --- logN(Li)4 []? Li abundance for Teff = 4750 K
38- 43 F6.3 --- logN(Li)5 []? Li abundance for Teff = 5000 K
45- 50 F6.3 --- logN(Li)6 []? Li abundance for Teff = 5250 K
52- 57 F6.3 --- logN(Li)7 []? Li abundance for Teff = 5500 K
59- 64 F6.3 --- logN(Li)8 []? Li abundance for Teff = 5750 K
66- 71 F6.3 --- logN(Li)9 []? Li abundance for Teff = 6000 K
73- 78 F6.3 --- logN(Li)10 []? Li abundance for Teff = 6250 K
80- 85 F6.3 --- logN(Li)11 []? Li abundance for Teff = 6500 K
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Origin: AAS CD-ROM series, Volume 1, 1993
(End) Patricia Bauer [CDS] 12-Sep-1994