CDROM/AJ/V114/P0699 Spectrophotometry in Open Clusters (Clampitt+ 1997) ================================================================================ Spectrophotometry of 237 Stars in 7 Open Clusters Lori Clampitt and David Burstein <1997, AJ, 114, 699> =1997AJ..114..699C ================================================================================ Abstract: Spectrophotometry is presented for 237 stars in 7 nearby open clusters: Hyades, Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC 4665, and M39. The observations were taken by Lee McDonald and David Burstein using the Wampler single-channel scanner on the Crossley 0.9 m telescope at Lick Observatory from 1973 July through 1974 December. Sixteen bandpasses spanning the spectral range 3500-7780 A were observed for each star, with bandwidths 32, 48, or 64 A. Data are standardized to the Hayes-Latham system to mutual accuracy of 0.016 mag per passband. The accuracy of the spectrophotometry is assessed in three ways on a star-by-star basis. First, comparisons are made with previously published spectrophotometry for 19 stars observed in common. Second, (B-V) colors and uvby colors are compared for 236 stars and 221 stars, respectively. Finally, comparisons are made for 200 main sequence stars to the spectral synthesis models of Kurucz, fixing log g = 4.0 and [Fe/H] = 0.0, and only varying effective temperature. The accuracy of tests using uvby colors and the Kurucz models are shown to track each other closely, yielding an accuracy estimate (1 sigma) of 0.01 mag for the 13 colors formed from bandpasses longward of the Balmer jump, and 0.02 mag for the 3 colors formed from the three bandpasses below the Balmer jump. In contrast, larger scatter is found relative to the previously published spectrophotometry of Bohm-Vitense & Johnson (16 stars in common) and Gunn & Stryker (3 stars). We also show that the scatter in the fits of the spectrophotometric colors and the uvby filter colors is a reasonable way to identify the observations of which specific stars are accurate to 1 sigma, 2 sigma, .... As such, the residuals from both the filter color fits and the Kurucz model fits are tabulated for each star where it was possible to make a comparison, so users of these data can choose stars according to the accuracy of the data that is appropriate to their needs. The very good agreement between the models and these data verifies the accuracy of these data, and also verifies the usefulness of the Kurucz models to define spectrophotometry for stars in this temperature range (> 5000 K). These data define accurate spectrophotometry of bright, open cluster stars that can be used as a secondary flux calibration for CCD-based spectrophotometric surveys. (c) 1997 American Astronomical Society. Description: The final calibrated spectral energy distributions (SEDs; relative to 5556 A) for all 237 stars are given in Table 4 according to the cluster identification number, the star HD or BD number, and the night(s) of observation. Table 6 lists the observed B-V and uvby data as obtained from SIMBAD, together with the differences (observed minus predicted) between the colors predicted from the authors' spectrophotometry and the observed colors. File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- table4.dat 125 237 SEDs for 237 open cluster stars table6.dat 131 237 Star-by-star comparison to filter colors and Kurucz models -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 7 A7 --- ID *Star identification number 8 1X --- --- Blank 9- 13 A5 --- Night *Nights observed 14- 19 I6 0.001mag 3500 *[]?=9999 3500-5556 color 20 A1 --- u_3500 *[ :*] indicates larger error in color 21- 26 I6 0.001mag 3571 *[]?=9999 3571-5556 color 27 A1 --- u_3571 *[ :*] indicates larger error in color 28- 33 I6 0.001mag 3636 *[]?=9999 3636-5556 color 34 A1 --- u_3636 *[ :*] indicates larger error in color 35- 40 I6 0.001mag 4036 *[]?=9999 4036-5556 color 41 A1 --- u_4036 *[ :*] indicates larger error in color 42- 47 I6 0.001mag 4167 *[]?=9999 4167-5556 color 48 A1 --- u_4167 *[ :*] indicates larger error in color 49- 54 I6 0.001mag 4255 *[]?=9999 4255-5556 color 55 A1 --- u_4255 *[ :*] indicates larger error in color 56- 61 I6 0.001mag 4400 *[]?=9999 4400-5556 color 62 A1 --- u_4400 *[ :*] indicates larger error in color 63- 68 I6 0.001mag 4565 *[]?=9999 4565-5556 color 69 A1 --- u_4565 *[ :*] indicates larger error in color 70- 75 I6 0.001mag 4785 *[]?=9999 4785-5556 color 76 A1 --- u_4785 *[ :*] indicates larger error in color 77- 82 I6 0.001mag 5000 *[]?=9999 5000-5556 color 83 A1 --- u_5000 *[ :*] indicates larger error in color 84- 89 I6 0.001mag 5263 *[]?=9999 5263-5556 color 90 A1 --- u_5263 *[ :*] indicates larger error in color 91- 96 I6 0.001mag 5840 *[]?=9999 5840-5556 color 97 A1 --- u_5840 *[ :*] indicates larger error in color 98-103 I6 0.001mag 6300 *[]?=9999 6300-5556 color 104 A1 --- u_6300 *[ :*] indicates larger error in color 105-110 I6 0.001mag 6710 *[]?=9999 6710-5556 color 111 A1 --- u_6710 *[ :*] indicates larger error in color 112-117 I6 0.001mag 7100 *[]?=9999 7100-5556 color 118 A1 --- u_7100 *[ :*] indicates larger error in color 119-124 I6 0.001mag 7400 *[]?=9999 7400-5556 color 125 A1 --- u_7400 *[ :*] indicates larger error in color -------------------------------------------------------------------------------- Notes for file: table4.dat -------------------------------------------------------------------------------- ID: Number of star according to the following sources: Hyades (Hya): Van Bueren, 1952, B. A. N. 11, No. 432 Pleiades (Ple): Hertzsprung, E., 1947, Ann. Leiden Obs. 19, No. 1A alpha Per (Per): Heckmann, O., Dieckvoss, W., & Kox, H., 1956, A. N. 283, 109 Praesepe (Pra): Klein-Wassink, W. J., 1927, Groningen Publ. No. 41 Coma Berenices (Com): Trumpler, F. J., 1938, Lick Obs. Bull. 18, 167 IC 4665 (IC4): Kopff, 1943, Mitt. Hamburg Stw. 8, 52 M39 (M39): Ebbinghausen, E. G., 1940, ApJ 92, 434 Night: Night of observation + secondary standard star(s) used for night 1 July 17/18, 1973 M39 M39 33 2 Aug. 14/15 Pleiades Ple 785 3 Aug. 15/16 M39,alpha Persei Per 605 4 Sept. 15/16 Pleiades Ple 785 5 Sept. 16/17 Hyades Hya 56 6 Sept. 17/18 alpha Persei,Pleiades Ple 785 7 Sept. 18/19 Pleiades Ple 785 8 Sept. 20/21 Hyades Hya 56 9 Oct. 12/13 Hyades Hya 56 10 Oct. 13/14 Hyades Hya 56 11 Mar. 8/9, 1974 Hyades,Praesepe,Coma B. Hya 56 12 Mar. 9/10 Coma B. Com 60 13 Apr. 10/11 Praesepe Pra 300 14 May 6/7 Coma B. Com 60 15 May 7/8 Praesepe,Coma B.,IC 4665 Pra 300,Com 60 16 Aug. 9/10 IC 4665 IC4 62 17 Dec. 29/30 Hyades,Pleiades,alpha Persei Hya 56 stan If star is used as secondary standard for that cluster 3500, 3571, 3636, 4036, 4167, 4255, 4400, 4565, 4785, 5000, 5263, 5840, 6300, 6710, 7100, 7400: Spectrophotometric colors of the cited filter formed with the 5556 filter (15 colors). All colors are expressed in terms of 0.0001 magnitudes (e.g., a value of 1225 is a color of 1.225 mag). u_3500, u_3571, u_3636, u_4036, u_4167, u_4255, u_4400, u_4565, u_4785, u_5000, u_5263, u_5840, u_6300, u_6710, u_7100, u_7400: Indicator if error of observation known to be larger than typical error : = error of 0.03-0.06 mag; * = interpolated value from star color and bracketing observations. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table6.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- ID *Star identification number 9 1X --- --- Blank 10- 15 I6 --- HD_num []? HD number of star 16- 18 I3 h RAh Right Ascension 1950 from SIMBAD 19 1X --- --- Always ':' 20- 21 I2 min RAm R.A. 22 1X --- --- Always ':' 23- 26 F4.1 s RAs R.A. 27 A1 - DE- Declination sign 28- 29 I2 h DEd Declination 1950 from SIMBAD 30 1X --- --- Always ':' 31- 32 I2 arcmin DEm Dec. 33 1X --- --- Always ':' 34- 37 F4.1 arcsec DEs Dec. 38 1X --- --- Blank 39- 48 A10 --- Sp *Spectral type from SIMBAD 49 A1 --- Notes *Notes for particular stars 50- 54 F5.2 mag V apparent V mag from SIMBAD 55- 61 F7.3 mag B-V []?=9.999, observed B-V color from SIMBAD 62- 68 F7.3 mag u-b []?=9.999, observed u-b color from SIMBAD 69- 75 F7.3 mag v-y []?=9.999, observed v-y color from SIMBAD 76- 82 F7.3 mag b-y []?=9.999, observed b-y color from SIMBAD 83- 90 F8.3 mag d_B-V *[]?=9.999, B-V color diff, US-SIMBAD 91- 97 F7.3 mag d_u-b *[]?=9.999, u-b color diff, US-SIMBAD 98 A1 --- ed_u-b *[ :], bad u-b color comparision 99-104 F6.3 mag d_v-y *[]?=9.999, v-y color diff, US-SIMBAD 105 A1 --- ed_v-y *[ :], bad v-y color comparision 106-111 F6.3 mag d_b-y *[]?=9.999, b-y color diff, US-SIMBAD 112 A1 --- ed_b-y *[ :], bad b-y color comparision 113-118 F6.3 mag d_kurbl *[]?=9.999, Kurucz comparison, blue col 119-125 F7.3 mag d_kurrd *[]?=9.999, Kurucz comparison, red col 126-131 F6.2 mag Vabs *Absolute V mag -------------------------------------------------------------------------------- Notes for file table6.dat: -------------------------------------------------------------------------------- ID: See Note for Starnum in Table 4 Sp: Spectral type from SIMBAD. A colon on either spectral class or luminosity class indicates uncertainty. Notes: Data come from SIMBAD unless a note is given. The note code is: c = these stars are variable according to SIMBAD d = Luminosity class taken from Mendoza, E. E. 1967, Bol Ton y Tac 4, 149 e = Spectral class taken from Crawford, D. L. & Barnes, J. V. 1972, AJ 77, 862 f = Luminosity class taken from Crawford & Barnes d_B-V, d_u-b, d_v-y, d_b-y: The residuals from comparing the spectrophotometric colors with B-V, u-b, v-y, b-y colors from SIMBAD. The color transformations are as follows: Color Transformation Slope Z.P. error Johnson B-V Matthews & Sandage (1963) 1.072 0.433 0.021 Stromgren u-b 3500 - (4565+4785)/2 1.005 0.125 0.024 Stromgren b-y (4565+4785)/2 0.934 0.153 0.013 Stromgren v-y (4036+4167)/2 0.891 0.415 0.032 The color transformation for B-V was done using the airmass = 1 bandpass functions for B and V mag as given by Matthews & Sandage ed_u-b, ed_v-y, ed_b-y: If indicated by a colon (:), this color comparison was not used in determining the color transformations. d_kurbl, d_kurrd: These are the average residuals from the best fit of Kurucz main sequence model spectral energy distributions to the main sequence stars in our sample. d_kurbl are the residuals for the three colors with one passband falling below 4000 angstroms. d_kurrd are the residuals for the 12 colors with both passbands falling at or above 4000 angstroms. Note that the residuals from the Kurucz fit (d_kurbl and d_kurrd) are well-correlated with the residuals from the uvby fits (d_kurbl with del_u-b; d_kurrd with del_b-y), so that the size of the color residuals is a good indication of the error of spectrophotometric observation, as detailed in the paper. Vabs: The absolute V magnitude, extinction corrected, according to the following values for reddening and distances: dist(pc) E(B-V) Praesepe 180 0.03 Hyades 43 0.00 Coma Berenices 90 0.00 M39 290 0.06 Pleiades 180 0.06 IC 4665 470 0.17 alpha Persei 230 0.10 The distances are estimated by a direct fit of the ZAMS line from Mihalas & Binney (1981, Galactic Astronomy (Freeman, New York) p. 106) to the V vs. B-V diagrams as published in our paper. The reddenings come from the 5th edition of the Lund-Strasbourg Catalog (Lynga 1987, Luns Starbourg Catalogue, 5th ed. (Uppsala Obs., Uppsala)). ------------------------------------------------------------------------------- ================================================================================ (End) D. Burstein/L. Clampitt [ASU] Oct-01-1997