CDROM/AJ/V105/P2299 Ursa Major Group Lithium (Soderblom+ 1993) ================================================================================ The Evolution of the Lithium Abundances of Solar-Type Stars. II. The Ursa Major Group David R. Soderblom, Catherine A. Pilachowski, Stephen B. Fedele, & Burton F. Jones <1993, AJ, 105, 2299> =1993AJ....105.2299S ================================================================================ Abstract: We draw upon a recent study of the membership of the Ursa Major Group (UMaG) to examine lithium among 0.3 Gyr old solar-type stars. For most G and K dwarfs, Li confirms the conclusions about membership in UMaG reached on the basis of kinematics and chromospheric activity. G and K dwarfs in UMaG have less Li than comparable stars in the Pleiades. This indicates that G and K dwarfs undergo Li depletion while they are on the main sequence, in addition to any pre-main-sequence depletion they may have experienced. Moreover, the Li abundances of the Pleiades K dwarfs cannot be attributed to main-sequence depletion alone, demonstrating that pre-main-sequence depletion of Li also takes place. The Sun's Li abundance implies that the main-sequence mechanism becomes less effective with age, otherwise the Sun would have even less Li than it does. The hottest stars in the UMaG (T(eff) >~ 6800K) have Li abundances like those of hot stars in the Pleiades and Hyades and in T Tauris, and the two genuine UMaG members with temperatures near Boesgaard's Li chasm have Li abundances consistent with that chasm developing fully by 0.3 Gyr for stars with UMaG's metallicity ([Fe/H] = -0.08 +/- 0.09). We see differences in the abundance of Li between UMaG members of the same spectral types, indicating that a real spread in the lithium abundance exists within this group. File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- table1.dat 77 49 Lithium abundances of UMaG solar-type stars table2.dat 58 36 Colors and temperatures of UMaG candidates -------------------------------------------------------------------------------- Comments for file: table1.dat -------------------------------------------------------------------------------- Table 1 lists the results of observations from five different sources: the Hamilton spectrograph of the Lick Observatory (largest single source); the coude feed telescope at the Kitt Peak National Observatory; a Reticon detector at the focus of the 80-in coude camera at Lick Observatory; the 1.4 m Coude Auxiliary Telescope and Coude Echelle Spectrometer at the European Southern Observatory; and observations reported by Boesgaard et al. (1987) [ApJ, 325, 749] obtained at the CFHT and with the 5 m telescope on Mount Palomar with resolving power of about 50,000 and S/N >= 300. This table utilizes the membership information provided by Soderblom & Mayor (1993a) [AJ, 105, 226]. It contains data for (a) probable members, (b) possible members, and (c) probable non-members. The three parts of the table are delimited by header records with the letters 'a', 'b', or 'c' in column 1 (see the example below). In the following, the abbreviation "mas" stands for milliarcseconds. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1 A1 --- Delim *[abc] Delimiter separating the three groups 2- 9 A8 --- HD Henry Draper number 10 1X --- --- Blank 11-16 A6 --- HR Harvard Revised (HR) number 17 1X --- --- Blank 18-28 A11 --- Other Other name 29 1X --- --- Blank 30-33 A4 --- Sp Spectral type 34-35 2X --- --- Blank 36-39 F4.2 mag B-V (B-V) color 40 A1 --- u_B-V Colon, ':', in one case only, star HD 141003B 41-45 I5 K Teff *Effective temperature 46 A1 --- u_Teff Colon, ':', in one case only, star HD 141003B 47 1X --- --- Blank 48-63 A16 mas EW_meas *Measured equivalent width for Li 6708 A 64-65 2X --- --- Blank 66 A1 --- l_EW_mean [< ] Limiting character for EW_mean 67-68 I2 --- EW_mean Adopted mean equivalent width 69-70 2X --- --- Blank 71 A1 --- l_N_Li [< ] Limiting character for N_Li 72-76 F5.2 --- N_Li *Log of the lithium abundance, log(N(Li)) 77 A1 --- u_N_Li Uncertainty flag for N_Li -------------------------------------------------------------------------------- Notes for file: table1.dat -------------------------------------------------------------------------------- Delim: Delimiter character separating the three groups mentioned in the description ('a', 'b', or 'c'), or blank. If this byte is non-blank, the remainder of the record is a comment describing the records following. Teff: Effective temperature (average of the temperatures listed in Table 2) EW_meas: Measured equivalent width for Li 6708 Angstrom feature from the five data sources listed above. L=Lick Hamilton spectrograph; K=Kitt Peak; B=Boesgaard et al. (1988); R=Lick Reticon; E=ESO (see example below) N_Li: Log of the lithium abundance, log(N(Li)), where log N(H) = 12 -------------------------------------------------------------------------------- Comments for file: table2.dat -------------------------------------------------------------------------------- Table 2 lists the available temperature indicators for the program stars and the effective temperature values they imply. The photometry has been taken from Nicolet (1978, A&AS, 34, 1), Hauck & Mermilliod (1980, A&AS, 40, 1) and Mendoza (1967, Bol. Obs. Tonantzintla y Tacubaya, 4, 149). Note that no corrections for reddening have been made for these nearby (d <= 25 pc) stars. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- HD Henry Draper number 9-14 F6.2 mag B-V (B-V) 15-20 I6 K Teff_B-V Effective temperature inferred from (B-V) 21-27 F7.3 mag b-y []? Stromgren (b-y) 28-33 I6 K Teff_b-y []? Teff from (b-y) 34-40 F7.3 mag Beta []? Stromgren beta 41-46 I6 K Teff_Beta []? Teff from beta 47-52 F6.2 mag V-I []? Johnson (V-I) 53-58 I6 K Teff_V-I []? Teff from (V-I) -------------------------------------------------------------------------------- ================================================================================ (End) Lee Brotzman [ADS] 06-Mar-1995