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J/AJ/100/1191       Giants DDO photometry                    (Morrison+, 1990)

Where does the disk stop and the halo begin? Kinematics in a rotation field. Morrison H.L., Flynn C., Freeman K.C. <Astron. J. 100, 1191 (1990)> =1990AJ....100.1191M
ADC_Keywords: Stars, giant ; Photometry, DDO Abstract: A sample of G and K giants approximately 4kpc from the Sun, covering the abundance range from solar to extreme halo has been selected without kinematic bias in a field aligned to measure galactic rotation. Accurate abundances, distances, and radial velocities have been measured. This sample has been combined with nonkinematically selected solar neighborhood objects taken from the literature, in order to examine the kinematics of the transition from disk to "thick disk" to halo. The metal-rich objects in the sample, with 0>[Fe/H]>-0.8, rotate rapidly around the galactic center and have low azimuthal velocity dispersion, σφ=40±10km/s. For objects in the range -0.5>[Fe/H]>-0.8, we find a small value for the asymmetric drift of 35±10km/s. We associate these objects with the thick disk, confirming the kinematical results of Ratnatunga and Freeman (1989, Cat.V/65) and others. In the abundance range -1.0>[Fe/H]≥-1.6 we find, in addition to objects with normal halo kinematics, objects in a disk configuration, confirming the results of Norris, Bessell, and Pickles (1985ApJS...58..463N). This disk is rotating rapidly, Vrot=170±15km/s, and has a scale height of 1.4±0.7kpc, these kinematical and spatial properties are similar to those of the thick disk. We show that these objects have different kinematics from that of the globular clusters and a sample of local RR Lyraes in the same abundance range. This suggests to us that these objects are better associated with the thick disk than the halo, and we refer to them as "metal-weak thick-disk stars". Hence we suggest that the conventional chemical description of the thick disk (Gilmore and Wyse, 1985AJ.....90.2015G) be widened to include stars with abundances as low as [Fe/H]=-1.6. At the galactic plane, the density of these metal-weak thick-disk stars is similar to that of halo stars, so they significantly affect the measurement, from samples selected on abundance, of the components of the velocity ellipsoid for the halo in the solar neighborhood. For the halo giants in our sample we measure σφ=102±24 and Vrot=17±24km/s. The rotation velocity and velocity ellipsoid for the metal-weak halo in the solar neighborhood have been rederived for objects with [Fe/H]≤-1.6 from the large sample of Norris (1986ApJS...61..667N), thus removing the possibility of contamination by metal-weak thick-disk stars. We derive Vrot=25±15km/s and (σr, σφ, σθ)=(133±8, 98±13, 94±6)km/s. These values are more consistent with other information about the shape of the halo. For a description of the DDO photometric system, see e.g. GCPD/12 Description: The CCO measurement were made during the period 1986-1988, on the 2.3m telescope at Siding Spring Observatory. The spectroscopic observations were obtained with the Mount Stromlo 1.9m telescope during 1986 and 1987. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 67 169 DDO photometry of 169 K giant candidates table2.dat 52 113 Spectroscopic results of the giants
See also: II/164 : Catalogue of DDO photometry 88 (Mermilliod+ 1989) II/80 : Catalogue of homogeneous DDO photometry of bright stars (McLure+ 1981) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 11 A11 --- [MFF90] Object designation 13- 18 A6 --- Lum Luminosity class derived from DDO photometry 20- 21 I2 h RAh Right ascension (1950) 23- 24 I2 min RAm Right ascension (1950) 26- 29 F4.1 s RAs Right ascension (1950) 31 A1 --- DE- Declination sign (1950) 32- 33 I2 deg DEd Declination (1950) 35- 36 I2 arcmin DEm Declination (1950) 38- 39 I2 arcsec DEs Declination (1950) 41- 45 F5.3 mag C45-48 45-48 DDO colour index (σ=0.009) 47- 51 F5.3 mag C42-45 42-45 DDO colour index (σ=0.013) 53- 58 F6.3 mag C41-42 41-42 DDO colour index (σ=0.013) 60- 65 F6.3 mag C38-42 38-42 DDO colour index (σ=0.017) 67 I1 --- Nobs Number of DDO measurements
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 12 A12 --- [MFF90] Star designation 14- 18 F5.2 mag Vmag V magnitude (no reddening correction applied) 20- 23 F4.2 mag B-V B-V colour index (no reddening correction applied) 25- 26 I2 --- o_Vmag Number of BV observations 28- 31 I4 km/s RV ? Radial velocity (single measurement mean error σ=10km/s) 33- 34 I2 --- o_RV ? number of RV measurements 36- 40 F5.2 [Sun] [Fe/H] Metallicity 42- 46 F5.2 mag VMAG Absolute V magnitude 48- 52 I5 pc Dist Distance
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer, Francois Ochsenbein [CDS] 30-Aug-1999
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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