3 Photometry and distances

Table 3 gives characteristic photometric quantities and distances for all galaxies in our combined sample. Since the luminosity distribution is needed to calculate the mass-to-light ratio, we check the calibration of the adopted surface brightness profiles as follows. We take photoelectric aperture measurements of Burstein et al. ([1987]), correct them for extinction and convert to the distances listed in Table 3. The resulting aperture magnitudes are compared to the values obtained by integrating our (CCD-) SB profiles (converted to B-band when necessary) out to the radius of the aperture. Only two galaxies appear not correctly calibrated: NGC 1399 and NGC 7507. For these two cases we correct the final mass-to-light ratios to the aperture magnitude system given by Burstein et al. ([1987]).

 

 

Table 3: Photometry and distances for all galaxies in the sample. Column 1 gives the NGC number, Col. 2 the morphological type, Col. 3 the adopted distance, Col. 4 the total integrated magnitude as given in the RC3 (de Vaucouleurs et al. [1991]), Col. 5 the effective radius in arcsec, Col. 6 the source of the effective radius (b Bicknell [1989], bs BSG94, f Faber et al. [1989], g Gerhard et al. [1998], p Peletier et al. [1990], r Rix et al. [1997]), Col. 7 the photometric band, Col. 8 the source of the photometric data: Be is Bender (unpublished), B Bicknell et al. ([1989]), C90 Caon et al. ([1990]), C94 Caon et al. ([1994]), C Carollo et al. ([1994], [1997]), Da Davis et al. ([1985]), D Djorgovski ([1985]), GS Gerhard & Saglia (Sect. 3.5), G98 Gerhard et al. ([1998]), G Goudfrooij et al. ([1994]), J Jørgensen et al. ([1995]), Ke Kent ([1984]), K King ([1978]), L Lauer et al. ([1995]), LV Lauberts & Valentijn ([1989]), M Michard ([1985]), P Peletier et al. ([1990]), P97 Prugniel ([1997]). Where two author abbreviations are given separated by a comma, the first is for ground based and the second for HST data. Author abbreviations separated by a "+'' signify that their data were merged. Columns 9 and 10 are the inner and outer boundaries of the photometry in units of the effective radius, Cols. 11 and 12 similarly for the kinematic data. In case of NGC 3379 S denotes the data from Statler & Smecker-Hane ([1999])

NGC	type	d[Mpc]	$B_{\rm T}$	$R_{\rm e}$ ['']	Source	Band	Source	$R_{\rm min}^{\rm phot} [R_{\rm e}]$	$R_{\rm max}^{\rm phot} [R_{\rm e}]$	$R_{\rm min}^{\rm kin} [R_{\rm e}]$	$R_{\rm max}^{\rm kin} [R_{\rm e}]$
315	E2,cD	77.6	-22.25	68	p	B	P	0.056	1.4	0.002	1.13
1399	E1,cD	21.9	-21.15	42	b	B	B,L	0.0010	75.3	0.002	2.31
2434	E0-1	30.3	-20.08	24	r	B, V	C,C	0.0006	6.3	0.006	2.58
3379	E1	13.2	-20.36	35	f	B, R	Da	0.04	4.5	0.005	2.95
S										0.0	2.23
4374	E1	20.5	-21.47	57	p	B	M	0.009	7.8	0.005	1.17
5846	E0	35.9	-21.73	83	f	V	GS	0.0	6.7	0.004	1.19
6703	E0	28.0	-19.92	30	g	B	G98	0.003	2.4	0.006	2.61
7145	E0	28.4	-20.23	39	f	B	J	0.003	2.8	0.007	1.66
7192	E0	37.0	-20.65	34	f	R	C,C	0.0004	5.9	0.0006	0.75
7507	E0	26.9	-20.79	31	f	B	Be+LV	0.009	4.1	0.005	1.66
7626	E1 pec	55.1	-21.55	38	f	B	K+P,Be	0.0003	1.8	0.003	2.10
3193	E2	37.8	-21.06	24	bs	B	G	0.04	2.7	0.03	1.41
3640	E2	35.1	-21.37	33	bs	B	G	0.03	2.8	0.02	0.63
4168	E1	41.8	-21.00	45	bs	B	C90	0.005	5.4	0.01	0.67
4278	E1	22.6	-20.68	33	bs	B	G	0.03	2.9	0.02	0.45
4472	E1	20.5	-22.19	104	bs	B	C94	0.006	12.5	0.005	0.54
4486	E0	20.5	-21.97	110	p	B	C90	0.003	8.9	0.02	0.39
4486B	cE1	20.5	-17.20	3.1	bs	V	P97,L	0.007	6.5	0.2	2.79
4494	E1	10.7	-19.44	45	bs	B	G	0.02	1.8	0.01	0.71
4589	E2	46.6	-21.65	41	bs	B	G	0.03	2.2	0.02	0.77
4636	E0	20.5	-21.13	102	bs	B	C94,L	0.0001	6.4	0.02	0.33

Distances to elliptical galaxies are still uncertain and the scatter between the values based on different methods is considerable. Therefore, we have adopted the uniform set of group distances based on the Dn-sigma distance estimator from Faber et al. ([1989]; Col. R of their Table 3), converting to Mpc with a Hubble constant of H₀ = 65 km s^-1/Mpc. All M/L values listed below and shown in Figs. 20 and 21 are transformed to these "standard distances'' given in Table 3.

3.1 NGC 315

The SB-profile of Peletier et al. ([1990]) extends from 3.8 arcsec out to 91.8 arcsec. Since the kinematic data range further inwards than the photometric data the SB-profile was extrapolated using a power-law; the fitted slope is -1.01. This might overestimate the actual luminosity in the central regions since one might expect the cD galaxy NGC 315 to have a core with a shallower slope. Due to the outer cutoff of the SB-profile at R = 91.8 arcsec, the total luminosity is an underestimate because the slope of the density profile at the cutoff of the data is still larger than -3. This must then also be true for the $B_{\rm T}$ value from the RC3.

3.2 NGC 2434

The SB-profile is composite of V-band HST-data from Carollo et al. ([1997]) out to 10 arcsec and B-band ground-based data by Carollo & Danziger ([1994]). The HST data were shifted by 0.88 mag to give a smooth transition between the two data sets. Note that Faber et al. ([1989]) give an effective radius of 81 arcsec whereas Rix et al. ([1997]) took 24 arcsec. In our analysis we used the latter value, but this is used only as a scaling constant and has no influence on any of the derived quantities.

3.3 NGC 3379

For this galaxy we used the CCD surface photometry of Davis et al. ([1985]) in both the R- and B-bands.

3.4 NGC 4374

We used the photometry of Michard ([1985]). The innermost data point was removed.

3.5 NGC 5846

The V band surface brightness profile of NGC 5846 was derived from observations performed in March 1999 at the ESO 2.2 m telescope equipped with the Wide Field Imager. This instrument covers a $34\times33$ arcmin² field of view with a mosaic of $2\times4$ CCDs of 2K $\times$ 4K 15 $\mu$m pixels, with a scale of 0.238 arcsec/pixel. Six 5 minutes exposures were taken, shifted by 20 arcsecs in RA and Dec to fill the gaps between the CCDs. The reduction of the frames was performed under IRAF, using the mscred package to handle mosaic data. After the bias subtraction, sky flat-fielding, and frame combination (performed after the astrometric calibration) the resulting image is flat at the 1% level.

The isophote shape analysis was performed following Bender & Möllenhoff ([1987]). The procedure was improved in two aspects. Mask files were produced automatically from the "segmentation frames'' produced by the Sextractor program (Bertin & Arnouts [1996]). The surface brightness and integrated magnitude profiles following elliptical isophotes were computed from the averages of the unmasked pixels between the isophotes. Statistical errors were also derived from the measured rms. Radial profiles of surface brightness, ellipticity, position angle and higher order terms of the Fourier analysis are shown in Fig. 9. Note that the centers of the outer isophotes (at more than 500 arcsec from the center) are some 30 arcsec off the center of the inner ones. The surface brightness has been calibrated using the V-band photoelectric photometry of Colless et al. ([1993]). The comparison with data of Bender (unpublished) obtained with a small field of view CCD show good agreement up to 40 arcsec from the center, where the sky subtraction of Bender's data becomes unreliable.

Figure 9: The V-band surface brightness and isophote shape parameters of NGC 5846 as a function of the 1/4 power of the semimajor distance from the center

3.6 NGC 7145

The SB-profile of Jørgensen et al. ([1995]) was used; the last two data points seem to suffer from sky subtraction errors and were dropped.

3.7 NGC 7192

For NGC 7192 HST photometry from Carollo et al. ([1997]) is available. These V-band data were shifted by -0.47 mag to merge smoothly into the ground-based R-band data from Carollo & Danziger ([1994]). The HST-data were used out to 10.9 arcsec.

3.8 NGC 7507

The SB-profile is a composite of data from Bender (unpublished) and from Lauberts & Valentijn ([1989]). The outermost data point was not used since it might be affected by sky-subtraction errors. Because the kinematic data reach further in towards the center than the photometry, we extrapolated using a power-law. The fitted central slope of the SB-profile is -0.15.

3.9 NGC 7626

B-band ground-based data from King ([1978]) and Peletier et al. ([1990]) were merged with V-band HST-data (Bender, unpublished), after shifting the HST-data by -0.6 mag.

3.10 NGC 3193

The SB-profile was taken from the electronically available tables of Goudfrooij et al. ([1994]). The profile was slightly oversmoothed to avoid high frequency fluctuations in the density profile.

Figure 10: $\chi ^2$ versus circular velocity. Horizontal lines indicate the (rescaled) $95\%$ confidence levels. Models lying above that line are inconsistent with the kinematic data. The SC models are encircled. For NGC 7145 it lies outside the plot. Note that the scale of the $v_{\rm circ}$ axes is different for each column

Figure 11: $\chi ^2$ versus circular velocity for the galaxies with kinematics from BSG94. Horizontal lines indicate the (rescaled) $95\%$ confidence levels. Models lying above that line are inconsistent with the kinematic data. The SC models are encircled

3.11 NGC 3640

For this E2 galaxy the photometric data are from Goudfrooij et al. ([1994]). The data were extrapolated towards the center using a power-law to match the extent of the kinematic data; the fitted slope is -0.46.

3.12 NGC 4168

We used photometric data of Caon et al. ([1990]) for this E1 galaxy. The profile was slightly oversmoothed to ensure a monotonically decreasing density profile.

3.13 NGC 4278

For this galaxy we used the SB-profile of Goudfrooij et al. ([1994]); this was oversmoothed compared to the GCV estimation (see Sect. 4) and extrapolated towards the center; the fitted central slope is -0.50.

3.14 NGC 4472

The total B-band magnitude of NGC 4472 and the effective radius $R_{\rm e} = 104$ arcsec are comparable to the corresponding values for NGC 4486. The SB-data are taken from Caon et al. ([1994]).

3.15 NGC 4486

We used the photometry of Caon et al. ([1990]). For the effective radius we take the value of 110 arcsec given by Peletier et al. ([1990]).

3.16 NGC 4486B

NGC 4486B is a close companion of M 87 and is in some respects comparable to M 32, the compact companion of M 31. There is an HST SB-profile available from Lauer et al. ([1995]) to which ground-based data from Prugniel ([1997]) were added after shifting by 0.6 mag.

3.17 NGC 4494

We used B-band photometry by Goudfrooij et al. ([1994]) for this E1 galaxy. The profile was extrapolated towards the center employing a power-law; the fitted slope is -0.57.

3.18 NGC 4589

We used photometry by from Goudfrooij et al. ([1994]) and extrapolated the profile towards the center; the fitted slope is -0.50.

3.19 NGC 4636

HST-photometry by Lauer et al. ([1995]) and ground-based data by Caon et al. ([1994]) were merged. The HST-V-band data were shifted by 1 mag to provide a smooth transition.