J/A+A/169/14 Hydrogen-line survey of M31. III. HI Holes (Brinks+, 1986)
A high-resolution hydrogen-line survey of Messier 31.
III. HI holes in the interstellar medium.
Brinks E., Bajaja E.
<Astron. Astrophys. 169, 14 (1986)>
=1986A&A...169...14B 1986A&A...169...14B (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby; H I data; Interstellar medium; Radial velocities
Keywords: Andromeda Galaxy; Astronomical Models; H Lines; Interstellar Gas;
Galactic Structure; H II Regions; Radio Astronomy; Supernovae;
Astrophysics
Abstract:
An analysis is carried out of HI holes in M 31 as detected with the
Westerbork radiotelescope (WSRT). The holes range from 100-1000pc
across and represent missing masses ranging from 103 to
107M☉, which would require energies ranging from 10 to the
49th to 10 to the 53rd erg. The kinematic ages are projected to be
from 2.5-30 million years, with the production rate of the holes being
1/100000yr. The production rate estimate is used to derive a lower
limit for the occurrence of supernovae in M 31, about 0.001/yr.
Finally, a correlation is found between H I holes smaller than 300pc
and OB associations and H II regions.
Description:
The work presented here is based on the new high resolution HI survey
of M31, performed with the Westerbork Synthesis Radio Telescope
(WSRT). A full account of the observations, the calibrations, and the
data reduction is given in Paper I (Brinks & Shane 1984A&AS...55..179B 1984A&AS...55..179B).
The observations were made using the WSRT in its 1.5km configuration.
Five fields were needed, which were subsequently combined into a
single map, to cover most of the optical image of M31.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
00 42 44.33 +41 16 07.5 M31 = NAME Andromeda Galaxy
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 102 141 Observed properties of HI holes
table3.dat 64 141 Derived properties of HI holes
--------------------------------------------------------------------------------
See also:
VIII/7 : Hat Creek High-Latitude H I Survey (Heiles+ 1974-1976)
VII/112 : RC2 Catalogue (de Vaucouleurs+ 1976)
J/A+AS/31/439 : A Survey of HII Regions in M31 (Pellet+ 1978)
J/A+AS/61/451 : The 37W catalogue of radio sources in M31 (Walterbos+ 1985)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/141] Name of the hole (G1)
5- 9 A5 arcmin Xpos X coordinate from the center of the galaxy (1)
11- 15 A5 arcmin Ypos Y coordinate from the center of the galaxy (1)
17 I1 h RAh [0] Center of the hole hour of right
ascension (B1950)
19- 20 I2 min RAm [36/43] Center of the hole minute of right
ascension (B1950)
22- 25 F4.1 s RAs Center of the hole second of right ascension
(B1950)
27 A1 --- DE- [+] Center of the hole sign of declination
(B1950)
28- 29 I2 deg DEd [40/41] Center of the hole degree of
declination (B1950)
31- 32 I2 arcmin DEm Center of the hole arcminute of declination
(B1950)
34- 35 I2 arcsec DEs [0/60] Center of the hole arcsecond of
declination (B1950)
37- 42 F6.1 km/s HRV [-577/342] Radial heliocentric velocity,
VHel (2)
44- 48 F5.1 km/s DV [-29/25]? Expansion velocity (3)
50- 53 I4 pc FWHMI [80/1000] Full width at half depth along the
minor axis of the hole (4)
55- 58 I4 pc FWHMA [120/1400] Full width at half depth along the
major axis of the hole (4)
60- 62 I3 deg psi [0/170] Position angle, ψ of the major
axis of the hole, counter-clockwise with
respect to the north declination axis
64- 67 F4.1 K INT [7.5/66] Brightness temperature of the
ambient HI in the channel map at VHel
69- 72 F4.2 --- Contr [0.14/0.74] Contrast of the hole with respect
to its surroundings (5)
74 I1 --- Q [1/3] Quality of the hole (3=high quality)
76 I1 --- T [1/3] Type of the hole (6)
78 A1 --- C Class of the hole ("c"=complete; "p"=partial)
80-102 A23 --- Remarks Remarks
--------------------------------------------------------------------------------
Note (1): Positions of the centre of the hole in standard coordinates X and Y
with respect to the centre of the galaxy. Most positions are accurate
to 0.1'.
Note (2): Radial heliocentric velocity at which the hole is most clearly
defined. This value is accurate to one channel interval or 4.1km/s.
Note (3): Expansion velocity or half the measured velocity splitting in the
case of a Type 3 hole. In the case of a Type 2 hole the negative sign
indicates blue-shifted HI. For Type 1 holes no expansion velocity can
be measured and the entry is left open. The estimated accuracy to
which DV can be given is about 2km/s.
Note (4): Full width at half depth, FWHMI and FWHMA, measured in parsec along
the minor and major axes of the hole, not yet corrected for the size
of the beam. The accuracy is about 20-30pc.
Note (5): The contrast is defined as Contr=(INT-I50)/INT, where I50 is
the brightness temperature of the HI at half depth, as determined on
the basis of the cross-cuts through the channel map.
Note (6): According to the appearance of the holes on the two position-velocity
maps, three types are defined. See Figures 1-4.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/141] Name of the hole (G1)
5- 9 F5.2 kpc R [1.7/20.5] Position of the hole in polar
coordinates in the plane of M31
11- 15 F5.1 deg theta [2.6/351.2] Angle measured counter-clockwise
with respect to the north major axis of M31
17- 20 I4 pc Maj [0/1000] Full width at half depth along the
major axis of the hole (7)
22- 25 I4 pc Min [0/1400] Full width at half depth along the
minor axis of the hole (7)
27- 29 I3 deg PA [0/168] Position angle of the hole after beam
deconvolution, measured counter-clockwise with
respect to the north declination axis
31- 34 I4 pc Diam [11/1183]? Effective diameter of the hole (8)
36- 39 F4.2 --- Ratio [0/1]? Axial ratio of the hole (8)
41- 44 F4.2 --- nHI [0.1/1.3] Volume density of the HI surrounding
the hole (9)
46- 50 F5.1 Myr Age [2.2/663.3]? Kinematic age of the hole (10)
52- 57 F6.1 10+4Msun Mass [0.1/1165.2]? Indicative HI mass (11)
59- 64 F6.1 10+43J Energy [0.1/1859]? Indicative energy needed to produce
a hole in 1050erg (12)
--------------------------------------------------------------------------------
Note (7): Full width at half depth along the minor and minor axis of the hole,
after deconvolution for the beam of the observing instrument according
to the formulae given by Wild (1970AuJPh..23..113W 1970AuJPh..23..113W).
Note (8): Effective diameter of the hole defined as the geometric mean of the
dimensions of the hole listed in columns Maj and Min, i.e.
Diam=(MinxMaj)1/2, and the axial ratio of the hole defined as
Ratio=Min/Maj. In the case of an unresolved hole the entry for Diam is
left open, and the ratio is 0.0.
Note (9): Volume density of the HI surrounding the hole estimated on the basis
of the intensity in the integrated HI map and transformed to
atoms/cm3 according to formula (1):
nHI=1.823x1018IBcos(i/h)(2π)0.5
where IB is the total surface brightness in K.km/s and the factor
cos(i/h)(2π)0.5 converts the measured column density to volume density.
Note (10): Kinematic age of the hole in units of 106yr defined as
Age=Diam/(2xDV). This age estimate represents an upper limit to the
age of a hole. If the evolution of a hole follows that of an expanding
shell of swept-up interstellar material in the snowplough phase as
described by Weaver+ (1977ApJ...218..377W 1977ApJ...218..377W; see also
Bruhweiler+ 1980ApJ...238L..27B 1980ApJ...238L..27B), the age as listed in the table
should be reduced to 60% of its value.
Note (11): We evaluate the mass which might have been present at the position
of the hole under the assumption that the hole is entirely empty, that
π/6(Diam)3 is the characteristic volume of the hole, and that
nHI is the average HI volume density if the hole were not present.
Note (12): To facilitate comparisons with the work by
Heiles (1979ApJ...229..533H 1979ApJ...229..533H) for the shells in our Galaxy we use the
same expression as used by him for the energy deposited in the
interstellar medium, i.e.
E=5.3x1043nHI1.12(Diam/2)3.12DV1.4erg
--------------------------------------------------------------------------------
Global notes:
Note (G1): The holes are numbered according to their position in Xpos, starting
from positions south of the center of the galaxy.
--------------------------------------------------------------------------------
Nomenclature Notes: Table 2, <[BB86] NNN> in Simbad.
History:
Tables scanned by CDS.
References:
Brinks & Shane Paper I. 1984A&AS...55..179B 1984A&AS...55..179B
Brinks & Burton Paper II. 1984A&A...141..195B 1984A&A...141..195B
Brinks & Bajaja Paper III. 1986A&A...169...14B 1986A&A...169...14B This catalog
(End) Emmanuelle Perret [CDS] 05-Mar-2025