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Up: Line-of-sight velocity distributions of galaxies

2 Observations and data reduction

In alltogether 15 nights 55 long-slit spectra of 53 early-type galaxies were obtained using the ESO 1.52 m telescope equipped with a B&C Cassegrain spectrograph. The observation log is given in Table 2. The parameters of the instrumental setups are described in Table 3. Instrumental dispersions for the different setups were determined by measuring the width of night-sky emission lines and helium-argon lines in the calibration spectra. The seeing was typically 1.5-2arcsec. The detectors employed were all Ford Aerospace $2048 \times 2048$pixel CCDs with a pixel size of $15 \times 15~\mu{\rm m}^2$. The position angle of the slit was generally aligned with the optical major axis of the target galaxy.

The integration times range from 40 to 120 min. The observed sample contains little less than half of all early-type galaxies with systemic velocities < 3000 km s-1. Exceptions are NGC 3302 ( $v_\textrm{\scriptsize sys}$ = 4075 km s-1) and NGC 3309 ( $v_\textrm{\scriptsize sys}$ = 4057 km s-1). Table 1 lists the sample galaxies and their basic parameters.

The spectra were calibrated with the ESO images processing package MIDAS using standard procedures for bias subtraction and flat field correction. Artifacts produced by cosmic ray events were removed by applying a filtering algorithm and by visual inspection. The science spectra were bracketed by helium-argon calibration spectra in order to verify shifts along the dispersion due to instrumental flexure. No significant shifts were however detected. Wavelength calibration was performed on the science frames for each spectral row independently by fitting a third order polynomial, using the respective averaged helium-argon spectra as reference. The rms error of the dispersion curve was typically < 0.4 Å. A sky spectrum was derived for each galaxy spectrum by fitting each wavelength bin with a first order polynomial at the border regions of the frame uncontaminated by the contribution of the galaxy light. To obtain an acceptable S/N all over the spectra, several lines in spatial direction were averaged until S/N > 12 was reached, where necessary. Within the central 3 arcsec of the galaxies $S/N~\approx$ 35 is typical.

For the subsequent analysis of the stellar kinematics the fourier fitting method using Gauss-Hermite polynomials was used as described by van der Marel et al. (1993). Spectra of non-rotating K and M giants obtained in the same instrumental setup as the galaxy spectra were used as velocity templates. Typically 4 to 8 such template stars were observed in each observing run.


 

 
Table 1: Programme galaxies and their basic parameters
Object Object Type Type Type $B^0_{\rm T}$ $A_{\rm e}$ $V_\textrm{\scriptsize hel}$
(PGC[*]) (NGC/IC/UGC) (RC3[*]) (RSA[*]) (PGC) (ESO-Uppsala[*])
6588 IC 1729 SAB0-:   E 13.28 29.8 1495
13433 NGC 1404 E1 E2 E 10.89 26.7 1925
13609 NGC 1427 cD E5 E 11.76 32.9 1430
14695 NGC 1537 SAB0- pec? E6 LB 11.53 26.1 1371
14757 NGC 1549 E0 E2 E 10.58 47.5 1153
17196 NGC 1889 cD pec:   E M 14.1   2472
19476 NGC 2271 SAB0-   LB 12.11 64.3 2588
20047 NGC 2325 E4 E4 E 10.96 86.5 2248
20916 NGC 2380 SAB0:   LB 10.38 43.4 1775
21325 NGC 2434 E0 E0 E 11.43 40.5 1327
23304 IC 2311 E0:   E 11.00 17.7 1836
24352 UGC 4508 cE ?   S 14.90   1917
24590 NGC 2663 E   E 10.23 84.6 2048
25075 NGC 2699 E:   E 13.57   1825
26592 NGC 2887 SA0(s)- ?   L 11.72 27.4 2850
26601 NGC 2865 E3 E4 E 12.29 11.7 2581
26733 NGC 2872 E2   E 12.64 20.8 3226
26768 NGC 2888 cD: E2 E 12.98 14.7 2233
27885 NGC 2986 E2 E2 E 11.51 41.4 2264
28806 NGC 3078 E2 E3 E 11.93 23.8 2506
28845 NGC 3087 cD: E2 E 12.34 16.1 2662
29311 NGC 3136 E: E4 E 11.23 41.4 1647
29366 NGC 3125 E ? Amorphous E 13.16 9.2 1080
30314 NGC 3224 cD   E 12.48 15.3 3088
30671 NGC 3250 E4 E3 E 11.67 32.1 2883
30859 NGC 3258 E1 E1 E 12.27 27.4 2808
30875 NGC 3260 E pec:   E 13.06 25.0 2413
30949 NGC 3268 E2 E2 E 12.23 36.1 2761
31391 NGC 3302 SA0   L 13.16 20.4 4075
31466 NGC 3309 E3 E1 E 12.34 31.4 4057
32249 NGC 3377 E5 E6 E 11.13 33.7 689
33824 NGC 3557B E5:   E M 12.92   2855
33871 NGC 3557 E3 E3 E 11.13 37.8 3014
34160 NGC 3585 E7 E7/S01(7) E 10.53 39.5 1491
24513 NGC 3617 cD     13.26 11.9 1491
34709 NGC 3636 E0   E 13.19   1715
36918 NGC 3904 E2: E2 E 11.67 23.3 1750
37061 NGC 3923 E4 E4/S01(4) E 10.52 53.3 1607
37863 NGC 4033 E6 S01(6) E 12.52 16.1 1521
38411 NGC 4105 E3 S01/2(3) E M 11.21 41.4 1900
38417 NGC 4106 SB0(s)+ SB0/a (tides) LB 11.88 61.0 2189
39628 UGC 7354     E 14.66   1684
39659 NGC 4261 E2 E3 E 11.32 28.6 2200
43276 NGC 4697 E6 E6 E 10.03 75.4 1210
46330 NGC 5061 E0 E0 E 11.06 25.5 2065
48139 NGC 5237 I0 ?   E M 12.84 26.9 321
54646 NGC 5903 E2 E3/S01(3) E 11.76 35.2 2519
62589 IC 4797 cD pec: E5/S01(5) E 12.04 17.7 2582
64136 NGC 6861 SA0(s)-: S03(6) LB 11.78 22.8 2819
66318 NGC 7029 E6: S01(5) E 12.26 24.4 2818
66549 NGC 7049 SA(s)0 S03(4)/Sa L 11.42 47.8 2198
68020 NGC 7196 E: E3/S03(3) E 12.31 21.7 3007
70975 IC 5297     S 15.6    
1 Paturel et al. 1989.
2 de Vaucouleurs et al. 1991.
3 Sandage & Tammann 1981.
4 Lauberts & Valentijn 1989.



 

 
Table 2: Observation log
observing date galaxy integration position
run     time angle
1991 Mar. 24/25 NGC 3302 7200 s 28$^\circ$
    NGC 4697 3600 s 80$^\circ$
  Mar. 25/26 NGC 3309 7200 s 170$^\circ$
  Mar. 26/27 NGC 4105 7200 s 115$^\circ$
    NGC 4106 7200 s 115$^\circ$
1992 Jan. 29/30 NGC 1537 2$\times$2400 s 94$^\circ$
    NGC 2325 2$\times$2400 s 6$^\circ$
    NGC 2663 2$\times$2400 s 113$^\circ$
    NGC 3078 2400 s 15$^\circ$
    NGC 3268 2400 s 62$^\circ$
  Jan. 30/31 NGC 2271 2$\times$2400 s 91$^\circ$
    NGC 2865 2$\times$2400 s 128$^\circ$
    NGC 3087 2$\times$2400 s 126$^\circ$
    NGC 3136 2$\times$2400 s 126$^\circ$
  Jan. 31/Feb. 1 NGC 1549 2$\times$2400 s 4$^\circ$
    NGC 3250 2$\times$2400 s 136$^\circ$
    NGC 3258 2$\times$2400 s 55$^\circ$
  Feb. 1/2 NGC 1427 2$\times$2400 s 77$^\circ$
    NGC 2380 2$\times$2400 s 72$^\circ$
    NGC 3224 2$\times$2400 s 134$^\circ$
    NGC 3585 2$\times$2400 s 96$^\circ$
    NGC 3904 2400 s, 1200 s 0$^\circ$
  Feb. 2/3 NGC 2888 2$\times$2400 s 170$^\circ$
    NGC 2434 2$\times$2400 s 126$^\circ$
    NGC 2887 2$\times$2400 s 87$^\circ$
    NGC 5061 1800 s, 1500 s 95$^\circ$
1992 Aug. 25/26 NGC 5903 2$\times$2700 s 139$^\circ$
    IC 4797 2$\times$2700 s 145$^\circ$
    NGC 7029 2$\times$2700 s 69$^\circ$
    NGC 7196 2$\times$2700 s 47$^\circ$
    IC 1729 2700 s 142$^\circ$
    NGC 1404 2700 s 160$^\circ$
  Aug. 26/27 NGC 7049 2$\times$3600 s 57$^\circ$
  Aug. 28/29 NGC 6861 3600 s 140$^\circ$
1993 Feb. 16/17 IC 2311 3600 s 84$^\circ$
    NGC 2699 3600 s 50$^\circ$
    NGC 2986 3600 s 78$^\circ$
    NGC 3377 3600 s 36$^\circ$
    NGC 3923 3600 s 50$^\circ$
  Feb. 17/18 NGC 1889 3600 s 161$^\circ$
    NGC 3125 3600 s 111$^\circ$
    IC 5297 3600 s 0$^\circ$
    NGC 3617 3600 s 147$^\circ$
    NGC 4033 3600 s 47$^\circ$
    NGC 4261 3600 s 160$^\circ$
  Feb. 18/19 NGC 2663 3600 s 98$^\circ$
    NGC 2872 3600 s 32$^\circ$
    NGC 3260 3600 s 0$^\circ$
    NGC 3557B 3600 s 107$^\circ$
    NGC 3557 3600 s 30$^\circ$
    NGC 4697 3600 s 160$^\circ$
  Feb. 19/20 UGC 4508 5400 s 90$^\circ$
    NGC 3636 3600 s 90$^\circ$
    UGC 7354 5400 s 19$^\circ$
    NGC 5237 3600 s 128$^\circ$



 

 
Table 3: Observation parameters
date CCD spatial grating wavelength slit spectral instrumental
    resolution   range width resolution dispersion
  ESO-number [arcsec/pixel] ESO-number [Å] [arcsec] [Å/pixel] [km s-1]
1991 Mar. 24 - 25 13 0.81 25 4253-6836 2.0 2.788 169
1991 Mar. 25 - 28 13 0.81 10 4835-5735 1.7 0.974 51
1992 Jan. 29 - Feb. 3 27 0.81 10 5162-6659 2.0 0.970 53
1992 Aug. 25 - 29 27 0.81 10 5175-6687 2.0 0.969 39
1993 Feb. 16 - 20 24 0.81 10 5175-6687 2.0 0.969 39



 

 
Table 4: Measured emission lines of the sample galaxies
galaxy element $\lambda_0$ $\lambda$ FWHM v $\sigma$
    [Å] [Å] [Å] [km s-1] [km s-1]
UGC 4508 Fe II 5591.38 5626.0 2.0 1856.2 44
  Fe I 5595.06 5630.1 2.3 1877.5 50
  He I 5875.6 5912.1 2.1 1862.4 43
  [N II] 6548.1 6588.7 2.3 1858.8 43
  H$\alpha$ 6562.8 6603.4 (4.6) 1854.6 (85)
  [N II] 6583.4 6624.2 2.4 1859.3 44
NGC 1889 [N II] 6548.1 6603.2 5.0 2522.6 96
  H$\alpha$ 6562.8 6617.62 3.0 2504.2 56
  [N II] 6583.4 6638.7 5.0 2518.2 95
NGC 3125 Fe II 5591.38 5611.9 2.2 1100.2 48
  Fe I 5595.06 5615.8 2.2 1111.3 48
  He I 5875.6 5896.73 2.5 1078.1 52
  Fe II 6149.238 6171.83 2.6 1101.4 52
  [N II] 6504.9 6528.552 2.7 1090.1 51
  [N II] 6548.1 6571.7 2.6 1080.5 48
  H$\alpha$ 6562.8 6586.44 2.73 1079.9 50.7
  [N II] 6583.4 6607.26 2.6 1086.5 48
NGC 5237 [N II] 6548.1 6555.2 (6.1) 325.1 (114)
  H$\alpha$ 6562.8 6570.07 2.3 332.1 42
  [N II] 6583.4 6590.7 2.4 332.4 45
UGC 7354 Fe II 5619.9 5591.38 2.0 1529.2 44
  Fe I 5623.9 5595.06 2.2 1545.3 48
  Fe I 5832.69 5804.06 1.9 1478.8 40
  Fe III 5862.67 5833.65 2.8 1491.3 59
  Fe II 6180.79 6149.238 2.2 1538.2 44
  [O I] 6332.27 6300.3 2.1 1521.3 41
  [N II] 6538.16 6504.9 2.4 1532.9 45
  [N II] 6581.43 6548.1 2.2 1526.0 41
  H$\alpha$ 6595.7 6562.8 (5.3) 1502.9 (99)
  [N II] 6616.878 6583.4 2.47 1524.5 45.9


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