Catalog of Interstellar HI Shells Discovered in the SETHI Database
Shauna Sallmen1, Eric J. Korpela2,
Brooke B. Bellehumeur1,3, Elizabeth M. Tennyson1,4,
Kurt Grunwald1, Cheuk Man Lo1,5
1 University of Wisconsin - La Crosse, La Crosse, WI 54601 (Authors with multiple affiliations worked on paper as UW-L undergraduate students, but are now elsewhere)
2 Space Sciences Lab at University of California, Berkeley, CA, 94720
3 Milwaukee, WI
4 Materials Science and Engineering Department, University of Maryland, College Park, MD 20742
5 Hong Kong, China
SETHI Data
Both the
raw SETHI data cubes and the larger cubes used for this search are available
- SETHI survey parameters:
- Sky Coverage: 7.2o < Declination < 29.7o
- Angular resolution: 0.1o
- Spectral resolution: 0.25 km/s.
- Sensitivity: 0.25 K
- Raw data cubes: (produced by Kevin Douglas)
- 7.68o x 7.68o x 410 km/s.
- Pixels: 0.03o = 1.8 arcmin and 0.26 km/s
- Naming convention: sethi_raHH.H_decDD.D.fits identifies center of
maps in RA decimal hours and Declination decimal degrees
-
Larger data cubes used in search:
- 22.5o x 22.5o x 410 km/s.
- Pixels: 0.03o = 1.8 arcmin and 1.55 km/s
- Naming convention: RAhh.hDdd.d.fits identifies center of
maps in RA decimal hours and Declination decimal degrees
Tables
- Note: In all tables, click on the Shell ID to go to a page containing detailed
information on each shell.
Main Shell Table
(Download .csv)
Contains basic parameters for the 74 shells currently in the catalog
Contains the following columns:
- Shell ID: GSHlll+bb+vvv
- (lll,bb are Galactic coordinates of shell center at velocity vvv)
- Click on Shell ID for detailed info on each shell
- RA (hh mm), Dec (deg): Equatorial coordinates of shell center
- Vref: LSR Velocity at which feature is most "shell-like"
- ∆RA (hh mm), ∆Dec (deg): Angular extent of shell at reference
velocity
- V1 and V2: Min / Max velocities at which
object appears "shell-like"
- ∆Θ (deg): Mean Angular Diameter of shell at reference velocity
- Shape parameter s: Based on major / minor axis measurements (0 for a line, 1 for circular object)
- Quality parameter Q: Based on
- Fragmentation of shell walls (undesirable)
- consistency and persistence of shell-like feature
across velocity range (desirable)
- regularity of shape (desirable)
- Expansion Quality Parameter Qexp: Higher if
- Shell smaller towards velocity extremes, larger near central
velocity
- Signs of foreground / background walls at velocity slices
outside "shell-like" range
- Signs of expansion in position-velocity space
- Flag: An asterisk (*) in this column indicates the presence of a comment about
the shell on its individual website.
Table of Kinematic Distances
(Download .csv)
Contains Kinematic Distances for 27 shells with |b| < 15 degrees, using rotation curve of Brand & Blitz (1993)
Contains the following columns:
- Shell ID: GSHlll+bb+vvv
- Galactic Coordinates l & b in degrees
- Dref, Dmin, Dmax (kpc)
- Kinematic Distances corresponding to reference velocity,
with lower and upper limits based on velocity range at which object
appears "shell-like"
- Sref, Smin, Smax (pc)
- Sizes derived from mean angular diameter and kinematic distance
estimates
- Dref2, Dmin2, Dmax2 (kpc) and Sref2, Smin2, Smax2 (pc)
- Second distance / size option for inner galaxy
- Dashes for a value indicate that no solution could be found for it.
- Comment: Key code for comments regarding kinematic distances.
Key is at the bottom of the table. Unless otherwise specified, the
shells are clearly associated with Galactic plane gas, so the
kinematic distances should be relatively reliable.
Table of Expansion Velocities
(Download .csv)
Contains Expansion Velocity estimates for 12 shells with Qexp ≥ 4.0
Contains the following columns:
- Shell ID: GSHlll+bb+vvv
- Expansion Quality parameter Qexp
- Velocities of front (Vf) and rear (Vb)
walls (km/s), where possible
- Estimated Expansion velocity (km/s):
- V1 and V2: Min / Max velocities at which
object appears "shell-like", for comparison with Vf and
Vb
- Lower limit on expansion velocity (km/s):
- Vexp > (Vb - V1)/2 or
- Vexp > (V2 - Vf)/2
- Comment: Key code for comments regarding expansion velocities.
Key is at the bottom of the table.
Table of Derived Shell Properties
(Download .csv)
Contains upper limits on age and estimated energies for shells with
measurements of expansion velocity and/or physical size.
Contains the following columns:
- Shell ID: GSHlll+bb+vvv
- Age upper limit(s) t1 and t2 (Myr):
- Based on expansion velocity and physical diameter(s)
- Estimated Thermal Energies E1 and E2 (erg):
- Calculated for Pressure P/k = 3000 cm-3 K
- Estimated Kinetic Energies KE1 and KE2 (erg):
- Mass estimated from that initially enclosed in shell volume,
assuming constant density and calculated for
nH = 1 atom / cm3
- Estimated Total Energies ECh1 and ECh2 (erg):
- Calculated using Chevalier's (1974) formula,
assuming nH = 1 atom / cm3
Last Updated on 24 June 2014.