1 Introduction

In this paper we we present the kinematical information extracted from HI maps of the dwarf galaxy sample described by Stil & Israel (2002; hereafter Paper I). As neutral atomic hydrogen is one of the most extended observable components of a galaxy, its line emission provides an excellent tool to probe galaxy mass distributions. The dopplershift of a line profile is a direct measure of the projected rotation velocity at the position sampled. Its linewidth is a measure of the macroscopic chaotic motion of the gas and reflects its physical condition. Both rotation and velocity dispersion can be measured out to the edge of the HI distribution, which usually extends far beyond the stellar distribution. In the outer regions, rotational velocities are more or less constant, implying the presence of large amounts of matter even at the largest distances to the center. These rotation velocities are about three times higher than expected if only stars and gas would contribute to the mass; thus the amount of "unseen'' or "dark'' mass is about an order of magnitude higher than that associated with luminous matter.

   

Table 1: HI disk parameters from tilted-ring fits; inclination fitted.

Name	resolution	kinematic center		incl.	fixed/free	PA	$v_{\rm sys}$	scale
	arcsec	$\alpha_{1950}$	$\delta_{1950}$	degr.		degr.	$\rm km\ s^{-1}$	kpc/'
[1]	[2]	[3]	[4]	[5]	[6]	[7]	[8]	[9]
DDO 46	13.5	$\rm 7^h38^m 00\fs9\pm 0\fs4$	$\rm 40^\circ13'37''\ \pm\ \ 5''$	$\rm 45$	fixed	$\rm 270\pm5$	$362 \pm 2$	1.4
DDO 47	13.5	$\rm 7^h39^m 03\fs1$	$\rm 16^\circ55'13''$	$\rm 30$	fixed	$\rm 318\pm8$	$272 \pm 2$	0.58
	30	$\rm 7^h39^m 03\fs1$	$\rm 16^\circ55'13''$	$\rm 30$	fixed	$\rm 316\pm9$	$272 \pm 2$
DDO 48	13.5	$\rm 7^h54^m 46\fs4 \pm 0\fs2$	$\rm 58^\circ10'43''\ \pm\ \ 3''$	$\rm 75\pm1$	free	$\rm 356\pm1$	$1087\pm 1$	4.6
	30	$\rm 7^h54^m 46\fs4 \pm 0\fs3$	$\rm 58^\circ10'43''\ \pm10''$	$\rm 80\pm5$	free	$\rm 356\pm2$	$1088\pm 2$
NGC 2537	30	$\rm 8^h09^m 42\fs6 \pm 0\fs4$	$\rm 46^\circ08'40''\ \pm\ \ 4''$	$\rm 42\pm3$	free	$\rm 174\pm6$	$444 \pm 1$	1.9
UGC 4278	13.5	$\rm 8^h10^m 27\fs4 \pm 0\fs5$	$\rm 45^\circ53'52''\ \pm\ \ 4''$	$\rm 80\pm3$	free	$\rm 351\pm1$	$564 \pm 1$	1.9
NGC 2976	13.5	$\rm 9^h43^m 08\fs0 \pm 1\fs0$	$\rm 68^\circ08'57''\ \pm\ \ 5''$	$\rm 65\pm3$	free	$\rm 326\pm2$	$4 \pm 2$	1.0
	30	$\rm 9^h43^m 07\fs7 \pm 0\fs4$	$\rm 68^\circ08'52''\ \pm\ \ 4''$	$\rm 62\pm2$	free	$\rm 325\pm4$	$4 \pm 1$
DDO 83	13.5	$\rm 10^h33^m54\fs4 \pm 0\fs1$	$\rm 31^\circ48'24''\ \pm\ \ 2''$	$\rm 66\pm2$	free	$\rm 59 \pm3$	$582 \pm 2$	2.6
DDO 87	30	$\rm 10^h46^m17\fs0 \pm 0\fs5$	$\rm 65^\circ47'35''\ \pm\ \ 5''$	$\rm 63\pm4$	free	$\rm 239\pm3$	$338 \pm 2$	1.0
DDO 123	13.5	$\rm 12^h23^m47\fs0 \pm 0\fs3$	$\rm 58^\circ35'51''\ \pm\ \ 7''$	$\rm 25$	fixed	$\rm 201\pm4$	$722 \pm 1$	3.3
DDO 133	30	$\rm 12^h30^m26\fs8 \pm 1\fs2$	$\rm 31^\circ48'46''\ \pm15''$	$\rm 20$	fixed	$\rm 353\pm4$	$330 \pm 3$	1.5
DDO 168	30	$\rm 13^h12^m15\fs0 \pm 1\fs5$	$\rm 46^\circ11'24''\ \pm\ \ 6''$	$\rm 63\pm3$	free	$\rm 276\pm1$	$190 \pm 3$	1.0
DDO 185	30	$\rm 13^h52^m53\fs3 \pm 0\fs5$	$\rm 54^\circ08'30''\ \pm\ \ 4''$	$\rm 66\pm5$	free	$\rm 18 \pm2$	$140 \pm 2$	2.0
DDO 217	30	$\rm 23^h27^m32\fs1 \pm 1\fs1$	$\rm 40^\circ42'56''\ \pm 15''$	$\rm 46\pm5$	free	$\rm 35 \pm3$	$428 \pm 2$	2.7

Column designations: [1] Object name; [2] resolution of dataset used; [3] and [4] right ascension and declination (epoch 1950) of kinematic center and their rms scatter between radii; [5] inclination in degrees and its error if it was a free parameter in the fit; [6] flag indicating whether the inclination was a free parameter; [7] position angle in degrees and its rms scatter between radii; [8] heliocentric systemic velocity in $~{\rm {km~s^{-1}}}$ and its rms scatter between radii; [9] radial scale of the rotation curve in kpc/arcmin.

Notes: DDO 168 position angle is mean for radii 150'' and 180''; DDO 217 position angle is mean for radii larger than 150 arcsec.

   

Table 2: Rotation velocities (km s^-1) from tilted ring fits.

radius	DDO 46	DDO 47	DDO 47	DDO 48	DDO 48	NGC 2537	UGC 4278	NGC 2976	NGC 2976
$\arcsec$	HR	HR	LR	HR	LR	LR	HR	HR	LR
15	$15.8\pm5.2$	$20.6\pm0.1$		$30.0\pm7.6$			$8\pm5$	$20.9\pm5$
30	$36.0\pm4.4$	$24.5\pm1.5$	$24.4\pm0.4$	$47.5\pm0.3$	$40.9\pm3.9$	$46.2\pm2.0$	$25.6\pm1.5$	$28.8\pm3$	$29.6\pm1.3$
45	$41.2\pm3.2$	$27.1\pm3.0$		$59.4\pm0.3$			$40.1\pm0.5$	$40.4\pm1.8$
60	$44.3\pm3.7$	$25.7\pm1.6$	$27.1\pm0.5$	$66.8\pm0.4$	$63.3\pm9.8$	$53.4\pm4.3$	$50.1\pm1.4$	$49.6\pm2.8$	$51.6\pm0.3$
75	$46.0\pm3.7$	$30.4\pm1.0$		$72.0\pm0.2$			$59.3\pm0.5$	$61.5\pm0.4$
90	$44.8\pm6.6$	$36.1\pm0.5$	$36.4\pm0.5$	$74.9\pm0.1$	$74.3\pm6.7$	$63.2\pm3.3$	$68.5\pm1.1$	$69.1\pm1.2$	$69.2\pm0.1$
105		$41.7\pm0.5$		$76.6\pm0.5$			$76.4\pm0.3$	$71.1\pm0.4$
120		$48.2\pm1.1$	$47.9\pm0.5$			$71.9\pm5.2$	$82.5\pm2.5$	$71.5\pm0.2$	$71.7\pm0.3$
135		$55.0\pm0.5$					$87.4\pm2.1$
150		$62.0\pm0.8$	$60.6\pm0.4$				$87.6\pm1.8$
165		$66.4\pm0.7$
180			$68.0\pm1.3$
radius	DDO 83	DDO 87	DDO 123	DDO 133	DDO 168	DDO 185	DDO 217
$\arcsec$	HR	LR	HR	LR	LR	LR	LR
15	$23.7\pm7.5$		$26.1\pm0.9$
30	$35.6\pm0.4$	17.6$\pm$1.3	$35.5\pm4.8$	$34.6\pm5.7$	$11.2\pm2.0$	$17.8\pm4.7$	$26.1\pm7.5$
45	$46.1\pm0.2$		$50.8\pm0.4$
60	$51.7\pm0.3$	30.0$\pm$0.6	$41.8\pm0.2$	$50.3\pm14$	$26.6\pm2.0$	$28.1\pm0.4$	$58.7\pm6.0$
75	$51.0\pm3.0$		$49.3\pm0.8$
90		32.3$\pm$0.4	$55.5\pm0.2$	$65.8\pm11$	$29.7\pm1.1$	$40.1\pm0.5$	$66.2\pm3.8$
105			$59.9\pm0.7$
120		34.4$\pm$1.8	$63.1\pm3.0$	$75.7\pm2.1$	$39.4\pm1.4$	$47.3\pm0.3$	$68.1\pm3.3$
150				$75.1\pm4.2$	$42.4\pm1.0$	$51.9\pm2.3$	$72.5\pm2.8$
180					$44.3\pm0.5$		$74.9\pm3.3$
210							$77.0\pm0.8$
240							$78.1\pm2.1$

Note: HR is based on high-resolution (13.5'') fits; LR is based on low-resolution (30'') fits.

It is interest to determine the detailed kinematical conditions governing late-type dwarf galaxies. These galaxies are gas-rich, dynamically simple and relatively easy to observe. Their rotation curves trace the distribution of dark matter more directly than those of more massive galaxies, where the mass-to-light ratio of the stellar disk and bulge is a critical parameter. Interestingly, it has been suggested that in some dwarf galaxies, the stellar contribution to the total mass is quite small (Broeils 1992), and that this contribution decreases with decreasing maximum rotation curve velocity (Persic et al. 1996; Swaters 1999).