J/AJ/125/2502 Spectral indices of Galactic halo (Morrison+, 2003)
Mapping the galactic halo.
VI. Spectroscopic measures of luminosity and metallicity.
Morrison H.L., Norris J., Mateo M., Harding P., Olszewski E.W.,
Shectman S.A., Dohm-Palmer R.C., Helmi A., Freeman K.C.
<Astron. J. 125, 2502 (2003)>
=2003AJ....125.2502M 2003AJ....125.2502M
ADC_Keywords: Stars, halo ; Spectroscopy ; Magnitudes ; Abundances, [Fe/H]
Keywords: Galaxy: evolution - Galaxy: halo - Galaxy: kinematics and dynamics
Abstract:
We present our calibration of spectroscopic measures of luminosity and
metallicity for halo giant candidates and give metallicities and
distances for our first sample of spectroscopically confirmed giants.
These giants have distances ranging from 15 to 83kpc. As surveys reach
farther into the Galaxy's halo with K giant samples, identification of
giants becomes more difficult. This is because the numbers of
foreground halo K dwarfs rise for V magnitudes of 19-20, typical for
halo giants at 100kpc. Our photometric survey uses the strength of the
Mgb/H feature near 5170Å to weed K dwarfs out of the disk and
thick disk, but we need spectroscopic measures of the strength of the
Ca II K, Ca I λ4227, and Mgb/H features to distinguish between
the very metal-poor dwarfs and halo giants. Using a full error
analysis of our spectroscopic measures, we show why a signal-to-noise
ratio of ∼15pixel-1 at Ca I λ4227 and ∼10 at Ca II K is
needed for reliable luminosity discrimination. We use the Ca II K and
Mgb features to measure metallicity in our halo giants, with typical
errors (random plus systematic) of 0.3dex for [Fe/H] values from -0.8
to -3.0.
Description:
Spectra for halo giant candidates were taken during runs in 1999 May,
2000 January and March on the Kitt Peak National Observatory (KPNO)
4m, 2000 May on the Cerro Tololo Inter-American Observatory (CTIO) 4m,
and 2001 February on the Magellan I 6.5m telescope. The Kitt Peak
National Observatory (KPNO) 4m data were taken with the RC
spectrograph. The KP007 grating was used, giving a resolution of
3.5Å and a spectroscopic range from 3500 to 5900Å. The CTIO 4m
data were taken with the RC spectrograph and the KPGL1 grating, giving
a resolution of 2.8Å and a spectral range of 3500 to 6450Å. The
Magellan I data were taken with the B&C spectrograph, a 600 line
grating, a resolution of 2.5Å, and a wavelength range from 3850 to
5300Å. All observations were made at the parallactic angle in order
to minimize the loss of UV and blue light from the stars.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 96 18 Metallicity and color of dwarf standards
table2.dat 96 49 Metallicity and color of giant standards
refs.dat 86 50 References
table4.dat 66 17 Spectral indices for dwarf standards
table5.dat 66 46 Spectral Indices for giant standards
table6.dat 96 94 Spectroscopic Observations for Giant Candidates
table7.dat 72 30 Metallicities and distances for
spectroscopically confirmed giants
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 30 A30 --- Name Star name
31 A1 --- n_Name [a] Note on Name (1)
33- 37 F5.2 [Sun] [Fe/H] Metallicity
38 A1 --- n_[Fe/H] [bc] note on [Fe/H] (1)
40- 44 F5.3 mag (b-y)0 ? Dereddened Stroemgren (b-y) colour index
46- 50 F5.3 mag (V-I)0 ? Dereddened Johnson (V-I) colour index
52- 55 F4.2 mag (B-V)0 ? Dereddened Johnson (B-V) colour index
57- 61 F5.3 mag (M-T2)0 Dereddened Washington (M-T2) colour index
62 A1 --- u_(M-T2)0 Uncertainty flag on (M-T2)0
64- 68 F5.3 mag E(B-V) Redenning
69- 83 A15 --- r_[Fe/H] References for [Fe/H], in refs.dat file
86- 91 A6 --- r_(b-y)0 References for photometry, in refs.dat file
92 A1 --- nr(b-y)0 [e] Note on r_(b-y)0 (1)
94- 95 I2 --- r_E(B-V) References for redenning, in refs.dat file
96 A1 --- nrE(B-V) [d] Note on r_E(B-V) (1)
--------------------------------------------------------------------------------
Note (1): Individual notes:
a: Chromospherically active star. This makes the K' index
unusable because of emission in the core of the K line
b: G251-53 is a common proper-motion pair of BD+80 245, which has
unusually low α-element abundances, [α/Fe]=-0.3
(Carney et al., 1997AJ....114..363C 1997AJ....114..363C), compared with the majority
of halo stars, which have [α/Fe]~+0.4
c: HD 134440 has low-element abundances, [Ca/Fe]=0.22, [Mg/Fe]=-0.11,
King, 1997AJ....113.2302K 1997AJ....113.2302K.
e: V-I observations obtained using V magnitude from Cudworth
(1979AJ.....84.1312C 1979AJ.....84.1312C) and V-I cluster giant branch from
Johnson & Bolte (1998AJ....115..693J 1998AJ....115..693J).
d: E(B-V) estimated using Schlegel et al. (1998ApJ...500..525S 1998ApJ...500..525S)
reddening, distance estimate, and reduction in line-of-sight
reddening from Bond (1980ApJS...44..517B 1980ApJS...44..517B).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 56 A33 --- Aut Author's name
58- 87 A30 --- Com Comments
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 30 A30 --- Name Star name
32- 36 F5.2 [Sun] [Fe/H] Metallicity
40- 43 F4.2 mag (M-T2)0 Dereddened Washington (M-T2) colour index
44 A1 --- u_(M-T2)0 Uncertainty flag on (M-T2)0
47- 51 F5.2 mag K' K' index (Beers, 1999AJ....117..981B 1999AJ....117..981B)
55- 59 F5.2 mag CaI CaI (4227Å) index metallicity measurement
62- 66 F5.2 0.1nm Mg Mg index metallicity measurement
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.3 deg GLON Galactic longitude (G1)
9- 15 F7.3 deg GLAT Galactic latitude (G1)
17- 21 F5.2 mag Mmag The Washington M-band magnitude
23- 26 F4.2 mag M-T2 The Washington (M-T2) color
28- 32 F5.3 mag e_M-T2 Error in M-T2
34- 37 F4.2 mag C-M The Washington (C-M) color
39- 43 F5.3 mag e_C-M Error in C-M
45- 49 F5.2 mag M-51 The Washington (M-51) color
51- 55 F5.2 [---] [Fe/H]K The K' index metallicity measurement
57- 61 F5.2 [---] e_[Fe/H]K Error in [Fe/H]K
63- 67 F5.2 [---] [Fe/H]CaI The Ca I (4227) index metallicity measurement
69- 73 F5.2 [---] e_[Fe/H]CaI Error in [Fe/H]CaI
75- 79 F5.2 [---] [Fe/H]Mg The Mg index metallicity measurement
81- 84 F4.2 [---] e_[Fe/H]Mg Error in [Fe/H]Mg
86 A1 --- Lum [rgsd] Luminosity classification (1)
88- 90 A3 "month" Obs.M Month of the observation
92- 95 I4 yr Obs.Y ? Year of the observation
--------------------------------------------------------------------------------
Note (1): Luminosity classification:
r = Needs repeat observation;
g = Giant;
s = Subdwarf;
d = Dwarf.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.3 deg GLON Galactic longitude (G1)
9- 15 F7.3 deg GLAT Galactic latitude (G1)
17- 21 F5.2 [---] [Fe/H]P The photometry-derived metallicity
23- 26 F4.2 [---] e_[Fe/H]P Error in [Fe/H]P
28- 32 F5.2 [---] [Fe/H]S The spectroscopy-derived metallicity
34- 37 F4.2 [---] e_[Fe/H]S Error in [Fe/H]S
39- 43 F5.2 kpc Dist Distance
45- 48 F4.2 kpc e_Dist Error in Dist
50- 59 A10 --- Field Field identification
61 I1 --- Chip Chip number
63- 66 I4 pix Xpix The X pixel coordinate
68- 71 I4 pix Ypix The Y pixel coordinate
--------------------------------------------------------------------------------
Global notes:
Note (G1): Objects identified as [MNM2003] LLL.lll+BB.bbb in Simbad
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Morrison et al., Paper I 2000AJ....119.2254M 2000AJ....119.2254M
Dohm-Palmer et al., Paper II 2000AJ....120.2496D 2000AJ....120.2496D
Hardinf et al., Paper III 2001AJ....122.1397H 2001AJ....122.1397H
Morrison et al., Paper IV 2001AJ....121..283M 2001AJ....121..283M
Dohm-Palmer et al., Paper V 2001ApJ...555L..37D 2001ApJ...555L..37D
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 16-Jun-2003