Table of Contents

Apart from giving the eccentricity of the ellipse ("bar")
in the disk, and the inclination of the disk, the two angles in this routine
are **theta** and **phi**, of which only one needs to be given.

For some input parameters an array is allowed to create an output table, which can then be easily plotted.

**ba=**- Axis ratio of bar. An array is allowed,
in
*nemoinp(1NEMO)*notation. No default. **inc=**- Inclination of disk in which the ellipse ("bar") is located. An array is allowed. No default.
**phi=**- Angle
between bar and disk in sky plane. An array is allowed. Either phi or theta
(not both) are required. It determines if projection (
**theta**given) or deprojection (**phi**given) is done. **theta=**- Angle between bar and disk in galax plane. Again an array is allowed.
**a=**- Length of the bar (currently only projected)
bar. If this option is used, the stick formulae (ba=0) will be applied,
and errors can be computed using
**dphi=**. **dba=**- Error term in b/a. Useful if you want to compute errors in (de)projected parameters using nsim=
**dphi=**- Error term in phi.
**nsim=**- Number of monte carlo to perform to compute an error term. [0]
**seed=**- Seed for random number generator. [0]

% ellipse 0.3 45 20:30:2 De-projecting ellipse: b/a inc phi b/a’ theta phi_kin 0.3 45 20 0.376558 29.4085 -46.4712 0.3 45 22 0.368488 31.9773 -45.7525 0.3 45 24 0.360246 34.4675 -44.8267 0.3 45 26 0.351921 36.8805 -43.7464 0.3 45 28 0.343591 39.2183 -42.5507 0.3 45 30 0.335325 41.4834 -41.2693

and here a plot that shows how the axis ratio of a 0.5 bar changes as the
bar angle changes, for fixed inclincation of 20 degrees:

% ellipse 0.5 1:89:1 20 | tabplot - 2 4 line=1,1

Here is an example of creating a bar in a disk, and viewing the sky
projection. The example is taken from NGC 253 (see also *rotcur(5NEMO)*
):

# disk r_d=2 pa_d=230 inc_d=76 # bar a_b=1 b_b=0.25 pa_b=18 # create bar and disk mkconfig - 361 ring $a_b | snapscale - - rscale=$b_b,1,0 | snaprotate - bar0 $pa_b,$inc_d,$pa_d zyz mkconfig - 361 ring $r_d | snaprotate - disk0 $inc_d,$pa_d yz # add, and plot the two ellipses snapadd disk0,bar0 - | snapplot -

Skillman et al. A&A 198, 33 (1988), p39. Arnaboldi et al. 1995AJ....110..199A Kinematics of the Ionized Gas in NGC 253

fall-1986V0.0 formulae derived for Skillman et al paperPJT 23-Apr-03V0.3 added phi_kinPJT 28-aug-03V0.4 added a= for stick formulae of bars, +errorsPJT