Figure 1.
Maximum rotation speed plotted against absolute blue magnitude.
Arrows pointing to the right are lower limits to the maximum
rotation speed because
the rotation curve was not observed to level off.
Open squares are upper limits to the rotation speed because no rotation
was measured.
The spiral galaxies are from Broeils (1992), as is the solid line fit to
the spirals (modified for an H$_0$ of 65 km/s Mpc^{-1}).
The dashed lines are the solid line offset 3.9 magnitudes
in M_B, enough to encompass
the bulk of the scatter around the solid line.
M_B for the Im and BCD galaxies was corrected for internal absorption
assuming an E(B-V)_i of 0.05. Foreground absorption is taken from
Burstein & Heiles (1984) with the extinction curve of
Cardelli, Clayton, & Mathis (1989).
The rotation data for irregulars are taken from
Sargent, Sancisi, & Lo (1983);
Comte et al. (1986);
Skillman et al. (1988);
Carignan & Beaulieu (1989);
Lake & Skillman (1989);
Jobin & Carignan (1990);
Broeils (1992);
Puche et al. (1992);
Lo, Sargent, & Young (1993);
Simpson (1995);
Young & Lo (1996, 1997);
Broeils & Rhee (1997);
McIntyre (1997);
van Zee et al. (1997);
Wilcots & Miller (1998);
Stil (1999);
Swaters (1999); and
Hunter, Elmegreen, & van Woerden (2000).
(Support for this work was provided by the Lowell Research Fund
and the Friends of Lowell Observatory.
EWR was a summer student at Lowell
Observatory under the Research Experiences for Undergraduates program
operated by Northern Arizona University and funded by the National
Science Foundation under grant number 9423921.)
Figure 2.
W_{20}^{ci} is the full width of the integrated
HI profile at 20% intensity, corrected for instrumental broadening,
random motions, and inclination of the galaxy
(Bottinelli et al. 1990, Broeils 1992).
W_{20}^{ci} is approximately twice the maximum rotation speed
of the HI gas in the galaxy and so is related to the total mass
of the galaxy.
Those galaxies for which the correction for random motions is larger
than the observed W_{20} are assigned a W_{20}^{c} of 5 km s^{-1}
and then corrected for inclination. They are
shown as upper limits.
a) Upper panel:
The solid line is the relationship for spirals from Broeils (1992)
converted to an H_0 of 65 km s^{-1} Mpc^{-1}.
b) Bottom panel:
The mass in gas is taken to be 1.34 times the mass in HI, to account for He.
The mass in stars is 1.54 times the blue luminosity in solar units.
The solid line is our least squares fit to the spirals.
The dashed lines are the solid line offset 0.7 in the logarithm
of the mass, enough to encompass
the bulk of the scatter around the solid line.
(Support for this work was provided by the Lowell Research Fund
and the Friends of Lowell Observatory.
EWR was a summer student at Lowell
Observatory under the Research Experiences for Undergraduates program
operated by Northern Arizona University and funded by the National
Science Foundation under grant number 9423921.)
Table 1.
(Support for this work was provided by the Lowell Research Fund
and the Friends of Lowell Observatory.
EWR was a summer student at Lowell
Observatory under the Research Experiences for Undergraduates program
operated by Northern Arizona University and funded by the National
Science Foundation under grant number 9423921.)
Figure 2.
W_{20}^{ci} is the full width of the integrated
HI profile at 20% intensity, corrected for instrumental broadening,
random motions, and inclination of the galaxy
(Bottinelli et al. 1990, Broeils 1992).
W_{20}^{ci} is approximately twice the maximum rotation speed
of the HI gas in the galaxy and so is related to the total mass
of the galaxy.
Those galaxies for which the correction for random motions is larger
than the observed W_{20} are assigned a W_{20}^{c} of 5 km s^{-1}
and then corrected for inclination. They are
shown as upper limits.
a) Upper panel:
The solid line is the relationship for spirals from Broeils (1992)
converted to an H_0 of 65 km s^{-1} Mpc^{-1}.
b) Bottom panel:
The mass in gas is taken to be 1.34 times the mass in HI, to account for He.
The mass in stars is 1.54 times the blue luminosity in solar units.
The solid line is our least squares fit to the spirals.
The dashed lines are the solid line offset 0.7 in the logarithm
of the mass, enough to encompass
the bulk of the scatter around the solid line.
(Support for this work was provided by the Lowell Research Fund
and the Friends of Lowell Observatory.
EWR was a summer student at Lowell
Observatory under the Research Experiences for Undergraduates program
operated by Northern Arizona University and funded by the National
Science Foundation under grant number 9423921.)
Table 1.
(Support for this work was provided by the Lowell Research Fund
and the Friends of Lowell Observatory.
EWR was a summer student at Lowell
Observatory under the Research Experiences for Undergraduates program
operated by Northern Arizona University and funded by the National
Science Foundation under grant number 9423921.)