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Notes for object MESSIER 031

23 note(s) found in NED.


1. 2009MNRAS.397.2148G
Re:MESSIER 031
NGC 224, better known as Andromeda, has not been included because the nucleus is
not a pressure-supported star cluster in which the stars have random motions but
is a rotationally supported nuclear disc.

2. 2008MNRAS.386.2242H
Re:NGC 0224
NGC 224 (M31), NGC 3031 (M81) and NGC 3115 in our sample are typical
classical bulges listed in KK04.

3. 2008MNRAS.386.2242H
Re:NGC 0224
NGC 224 (M31), NGC 3031 (M81) and NGC 3115 in our sample are typical classical
bulges listed in KK04.

4. 2007MNRAS.382.1552L
Re:NGC 0224
NGC 224 - M 31: The M31 nucleus is highly compact, and is the prototype of the
central luminous star clusters found in many galaxies. The bulk of its stellar
population corresponds to an old (>~10 Gyr) metal-rich component (Bica et al.
1990). This is also reproduced by our synthesis analysis. The central 1 kpc of M
31 contains several ionized gas clouds, which interestingly have different line
ratios, placing them in the Seyfert, LINER or star-forming regions of line ratio
diagrams (delBurgo et al. 2000).

5. 2002ApJ...574..740T
Re:MESSIER 031
M31.
The modeling is complicated by the double nucleus. Kormendy & Bender
(1999) find M_BH_ = (3.0 +/- 1.5) x 10^7^ M_sun_, although this result
relies heavily on the small displacement between the center of light
of the nucleus and bulge. Tremaine (1995) and Bacon et al. (2001) find
M ~ 7 x 10^7^ M_sun_ but without detailed model fitting. We adopt the
range (2.0-8.5) x 10^7^ M_sun_.

6. 2002AJ....124..675C
Re:UGC 00454
M31. The 1.4 GHz flux density is from the NRAO 91 m telescope
(Dennison et al. 1975).

7. 2001ApJS..132..129M
Re:NGC 0224
NGC 224 (M31). - The Andromeda galaxy, a member of the Local Group, is
a disk system, type SA(s)b, ~690 kpc in distance, and inclined 78^deg^ to
our line of sight. Several low-resolution, wide field UV images of M31 were
obtained with both balloon (Deharveng et al. 1980) and rocket experiments
(Deharveng et al. 1976; Carruthers, Heckathorn, & Opal 1978; Bohlin et al.
1985; Bohlin et al. 1988), the latter two in both FUV and MUV bands. The
best of these images achieved a spatial resolution of ~15" and showed that
the UV emission from M31 is dominated by the bulge and a broken ring of OB
associations.
UIT imagery was obtained in two overlapping fields during Astro-1; M31
completely fills the field of view in both. One field is centered on the
bulge; the other is centered ~40' to the southwest along the major axis.
Images in each filter have been combined and are displayed as mosaics in
Figures 5a-5b. The radial UV surface brightness and color profiles plotted
in Figures 5a-5b, respectively, are based on mean values within those
segments of the elliptical apertures which lie within our mosaic. The
profiles therefore reflect behavior only near the southwestern major axis
for r < 50'. The R-band profile shown in Figures 5a5b was interpolated from
the major axis profile data taken from Kent (1987).
The bulge is extended in both FUV and MUV and displays a relatively
smooth appearance; neither bright substructure nor dust lanes are evident.
As in the case of M81, the bulge of M31 is considerably more prominent at
longer wavelengths, though the contrast is not as extreme as in M81. In
both FUV and MUV light, the inner bulge follows a reasonably good
de Vaucouleurs r^0.25^ profile to r ~ 90". Except at very small radii where
the spatial resolution of the data are mismatched, the bulge shows only a
small color gradient in (25-R). However, the FUV light is more centrally
concentrated, producing a strong radial color gradient in (FUV-MUV) for
0 <~ r <~ 150", in which the light gets redder with increasing radius. This
behavior is typical of large spiral bulges and elliptical galaxies but is
much larger in amplitude and is reversed in sense from gradients in the
optical bands such as (B-V) or (V-K) (O'Connell et al. 1992; Ohl et al.
1998).
There are no detected UV point sources in the bulge, even though
individual stars as faint as B1 V (m(MUV) ~ 18.4) would be above the MUV
threshold (O'Connell et al. 1992). If the FUV light from the bulge
originated in recently formed massive stars with a normal initial mass
function, there would be ~200 OB stars visible within r <~ 2'. Their
absence supports the interpretation of the FUV light as originating from
low-mass, post-giant branch stars (e.g., Greggio & Renzini 1990;
O'Connell 1999). HST UV observations of the core of M31 have been
presented by King et al. (1992); Bertola et al. (1995); King, Stanford,
& Crane (1995); and Brown et al. (1998). At HST resolution, the nucleus of
M31 is double, and the component coincident with the dynamical center has
UV colors which are bluer than those of the background bulge and therefore
may contain massive stars formed through stellar collisions (King et al.
1995; Lauer et al. 1998). The second, off-nuclear component has UV colors
similar to the bulge. These sources are not resolved in the UIT photometry.
Brown et al. (1998) have partially resolved the hot stellar population
responsible for the FUV light in the central 14" x 14" using HST/FOC
images. Color-magnitude diagrams of the resolved stars are consistent with
objects that have evolved from the extreme horizontal branch.

8. 2001ApJS..132..129M
Re:NGC 0224
Outside the bulge, the MUV light profile roughly parallels the R-band
profile. However, the FUV profile flattens and even rises slightly with
increasing radius, meaning that the (FUV-MUV) color becomes systematically
bluer with radius. This result is preliminary because of the difficulty in
determining the sky background (see section 4). The existence of a smooth
radial distribution of FUV emission at small radii suggests the presence of
an FUV-bright inner disk which spatially overlaps with the outer bulge.
Such an inner disk is not seen in the case of M81 (NGC 3031, see Fig. 17a),
where the combined FUV light of the bulge and disk is undetectable at inner
radii (r < 3.5' = ~3.5 kpc). The surface brightness profiles are quite
different between these two objects, despite the fact that M81 is only
slightly earlier in Hubble type (Sab rather than Sb).
The outer disk of M31 is rich in UV-bright massive stars, the brightest
concentration of which is NGC 206, located ~5' from the southwestern edge
of the mosaics shown in Figures 5a-5b. Hill et al. (1992a) provide UV
photometry of 30 resolved stars in NGC 206; most are evolved OB stars with
30 <~ M/M_sun_ <~ 60. Hill et al. (1993c, 1995b) presented enlargements of
the UIT images for some 60 OB associations in M31 and photometered
individual stars and integrated light. They infer a maximum stellar mass
of 85 M_sun_. Only about 40% of the integrated MUV light and 20% of the FUV
light of a typical association comes directly from the resolved stars; the
remainder may be dust-scattered starlight with a smaller contribution from
fainter stars with T >~ 10,000 K. Bohlin et al. (1993) obtained UV
photometry for 43 compact clusters; most of these are old globulars, but
seven appear to be compact young clusters. The disk shows a strong
(FUV-MUV) color gradient, becoming systematically bluer from r ~ 3' to
r ~ 50' (~10 kpc) by about 2 mag. This reflects the increasing contribution
of OB associations to the total integrated light at larger radii.

9. 2001A&A...374..394V
Re:NGC 0224
NGC 224: The discrepancy observed along the NE axis between our data and
those by Kormendy (1988) and by Dressler and Richstone (1988) may be the
result of an incorrect sky subtraction in our data. An overestimation of
the sky level due to the large size of the galaxy covering all the slit
area may produce the higher {sigma}_*_ and shift in V_*_ we actually
measure.

10. 2000MNRAS.319...17L
Re:NGC 0224
NGC 224 (M 31): No analysis of X-ray data for this galaxy has been done in
this paper. Einstein and ROSAT HRI observations of M 31 have detected over
100 individual sources with luminosities
10^36^ <~ L_X_ <~ 10^38^ erg s^-1^ (Trinchieri & Fabbiano 1991; Primini,
Forman & Jones 1993). The ROSAT PSPC, which is more sensitive than the HRI
(but with worse spatial resolution), gives an upper limit for a diffuse
component associated with the galactic bulge of 2.6 x 10^38^ erg s^-1^
(Supper et al. 1997).
The point sources are associated with two components, the disc and the
bulge, and are strongly concentrated towards the centre. PSPC data show
that the bulge and disc components account for about one and two thirds of
the total emission, respectively (Supper et al. 1997). Ginga (2-20 keV) and
BeppoSAX (0.1-10 keV) observations have shown that this emission from the
galaxy is consistent with a population of low-mass X-ray binaries (LMXRBs)
(Makishima et al. 1989; Trinchieri et al. 1999). A list of the sources
found within ~6 arcmin of the nucleus is shown in Table 6. The source
coincident with the galactic nucleus has been reported to vary
(Primini et al. 1993), and is probably an XRB.

11. 1999A&AS..138..253B
Re:NGC 0224
NGC 224 - SN 1885A: five small patches (<= 1 arcsec) have been detected.
They all are red and bright (brighter than 20th V magnitude). The galaxy
light might contaminate the environment.

12. 1997AstL...23..644G
Re:MESSIER 031
M 31. Van den Bergh (1992) (a recommendation that is based on an analysis of
the studies of other authors); Berkhuijsen et al. (1988)(nos. 1583, 2621, 820),
(nos. 4391, 4652, 4640). The brightest red stars were identified using the
criteria (B-V> 1.8 and 0.8<(V-R)<1.2, and the brightest blue stars were
identified using the criterion (U-B)<0.0. In Nedialkov et al. (1989), the
brightest red stars (R4, R31, R36) and the brightest blue stars (nos. 79, 87,
27) are, respectively, 0.49^m^ and 1.90^m^ fainter. It should be noted that
there are no sufficiently complete data in the literature on the brightest red
and blue supergiants in M 31, and this is the least reliable case among our
samples of the brightest stars.

13. 1996ApJS..103...81C
Re:NGC 0224
NGC 0224.--M31. Multiconfiguration mosaic of 1465 MHz VLA images in Braun
(1990).

14. 1994CAG1..B...0000S
Re:NGC 0224
M31
Local Group
SbI-II
PS-0-Hendricks
Hubble Atlas, p. 18
Sep 29/30, 1948
103aO
10 min
The print of M31 here is made from the first
plate taken with the Palomar 48-inch Schmidt
telescope after the final optical adjustments had
been made in 1948. The observer was Don 0.
Hendricks, chief optician of the Mount Wilson
Observatory and later the Mount Wilson and
Palomar Observatories. Hendricks had made the
optics of the 48-inch Schmidt, with its 72-inch
primary mirror, in the optical shop in the Mount
Wilson office complex between 1937 and 1941.
The superior optics of this largest of the Schmidt
telescopes (at the time) is well shown by the print
here. The field of view is about 3^deg^ on the long
side.
A description of M31 itself, chief member of
the Local Group, would be similar to that in the
Hubble Atlas and is not repeated here.

15. 1993ApJS...86....5K
Re:NGC 0224
NGC 224 (M31, Andromeda); Sb.
The UV spectrum of M 31 is basically concave, with a minimum in flux at
around 2000 A and an increase in flux to both longer and shorter
wavelengths. Absorption features of Si II, OI, Si III, and C II are
present between 1200 and 1350A, as well as Mg II {lambda}2800 (both
Galactic and from M 31) and Mg I {lambda}2850.
M31 is the best example in the atlas of a spiral (Sb) galaxy with the
center dominated by the bulge population (Burstein et al. 1988); the
spectrum resembles that of an elliptical galaxy, but with a less
prominent rising branch. Welsh (1982) observed the center of M 31 with
IUE and concluded that the rising branch did not come from young, metal-
rich stars because of the weak absorption features of Si IV and C IV near
1300 A. In the central region, Welsh also found that the blue stars are
more centrally concentrated than are the metal-rich red giants, based on
a comparison of the cross-dispersion profile in the UV with that in the
optical. Deharveng et al. (1982) derived an upper limit for the star
formation rate of 7.4 X 10^-5^ M_sun_ yr^-1^, by comparing the far-UV
luminosity with the predictions of the steady state UV flux of Lequeux et
al. (1981). The longer wavelength flux is presumably due to the main-
sequence turnoff and is dominated by late F stars (see the stellar
spectra in Fig. 5 for comparison).

16. 1976RC2...C...0000d
Re:NGC 0224
= Messier 031
Brightest in M31 (Local) Group.
Faint companions:
Ap. J. (Letters), 171, L31, 1972.
Andromeda I = A0043+37
Andromeda II = A0113+33
Andromeda III = A0032+36
Andromeda IV = A0039+40
Photograph:
Ap. J., 139, 1056, 1964.
P.A.S.P., 78, 367, 1966.
P.A.S.P., 78, 496, 1966.
A.J., 72, 65, 1967.
Astr. Ap., 9, 181, 1970.
Astrophys. Lett., 11, 173, 1972.
Ap. J. (Letters), 174, L71, 1972.
Ap. J., 179, 445, 1973.
Nucleus:
Ap. J., 140, 1467, 1964.
Ap. J., 170, 25, 1971.
Ap. J., 194, 257, 1974.
"Nuclei of Galaxies", 271, 1971.
IAU Symp. No.58, 336, 1974.
Photometry: (UBV)
Ap. J., 142, 1376, 1965.
Ap. J., 143, 187, 1966.
Ap. J., 157, 55, 1969.
Ap. J., 194, 257, 1974.
A.J., 71, 867, 1966.
Astr. Ap., 12, 1, 1971.
Bull. A.A.S., 4, 332, 1972.
Photometry: (12 Color)
Ap. J., 146, 36, 1966.
Photometry: (5 Color)
A.J., 73, 313, 1968.
Photometry: (10 Color)
Ap. J., 179, 731, 1973.
Photographic Isophotometry:
P.A.S.P., 82, 1032, 1970.
Photometry: (I.R. 1-25 microns)
Ap. J., 138, 1317, 1963.
Ap. J., 143, 187, 1966.
Ap. J. (Letters), 159, L165, 1970.
Bull. A.A.S., 1, 248, 1969.
Absorption and Color Excess:
A.J., 72, 526, 1967.
A.J., 74, 1000, 1969.
Astr. Ap., 24, 47, 1973.
Resolution and Distance Modulus:
A.J., 72, 526, 1967.
A.J., 72, 65, 69, 1967.
OB stars:
Ap. J. Suppl., 9, No. 86, 1964.
A.J., 71, 219, 1966.
IAU Symp. No. 38, 39, 1970.
A.N., 292, 103, 1970.
A.N., 292, 275, 1971.
A.N., 294, 79, 1972.
Variable Stars: (Novae, Cepheids)
IAU Circ. No. 1878, 1964.
A.J., 69, 610, 1964.
A.J., 70, 212, 1965.
A.J., 72, 1356, 1967.
Coll. Int. C.N.R.S., Paris, 125, 1965.
Ast. Tsirk., No. 560, 1970.
Ast. Tsirk., No. 579, 1970.
Sov. A.J., 12, 265, 1968.
Sov. A.J., 15, 1001, 1972.
Info. Bull. Var. Stars., No. 622, 1972.
Ast. Tsirk., No. 799, 1973.
Astr. Ap., 22, 453, 1973.
Astr. Ap. Suppl., 9, No. 3, 1973.
Distance Modulus: (From Cepheids)
Sov. A.J., 7, 293, 1963.
Bull. A.A.S., 3, 398, 1971.
Globular Clusters:
Vet. Publ. Astr. Inst. Univ. Brno., No. 5, 1966.
Bull. A.A.S., 1, 208, 1969.
J.R.A.S. Canada, 63, 95, 1969.
Ap. J.Suppl., 19, No. 171, 1969.
Sov. A.J., 12, 116, 1968. 17, 174, 1973.
Spectrum, Description and Photograph:
A.J., 74, 515, 1968.
Internal Motions:
IAU Symp. No. 29, 71, 1968.
Ap. J., 159, 379, 1970.
Ap. J., 181, 61, 1973.
Velocity Dispersion:
IAU Symp. No.15, 112, 1962.
Bull. A.A.S., 4, 315, 1972.
Ap. J., 180, 705, 1973.
IAU Symp. No. 58, 20, 1974.
Redshifts of Faint Background Objects:
Sov. A.J., 18, 144, 1974.
Spectrophotometry:
Ap. J., 139, 532, 1964.
Ap. J., 141, 109, 1965.
Ap. J., 154, 21, 1968.
Ap. J., 163, 249, 1971.
Ap. J., 164, 11, 1971.
Ap. J., 170, 25, 1971.
Ap. J., 177, 31, 1972.
A.J., 74, 150, 1969.
P.A.S.P., 82, 760, 1970.
IAU Symp. No. 44, 49, 1972.
Wells, Don, Univ. Texas. Dissertation, Austin, 1972.
Mem. S. A. Ital., 43, 263, 1972.
Bull. A.A.S., 4, 230, 1972.
Bull. A.A.S., 6, 442, 1974.
Astr. Ap., 26, 95, 1973.
Astr. Ap., 27, 433, 1973.
IAU Symp. No. 58, 169, 1974.
Spectrophotmetry (near UV):
IAU Symp. No. 36, 130, 1970.
Spectrophotmetry (far UV):
P.A.S.P., 81, 475, 1969.
N.A.S.A. SP 310, pp. 559-575, 1972.
Population Models:
P.A.S.P., 78, 380, 1966.
Ap. J. Suppl., No. 193, 1971.
Ap. J., 175, 649, 1972.
Astr. Ap., 20, 361, 1972
Astr. Ap., 33, 177, 1974.

17. 1976RC2...C...0000d
Re:NGC 0224
Globular Clusters:
Ap. J., 171, 403, 1972.
Molecular Absorption: (2.1 and 2.3 micron, H2O and CO)
Ap. Lett., 14, 1, 1973.
Polarization:
Astrofizika, 4, 409, 1968.
Dynamics, Rotation Curve, Mass Determination and M/L ratio:
Ap. J., 142, 1376, 1965.
Ap. J., 159, 379, 1970.
Ap. J., 170, 25, 1971.
Ap. J., 180, 605, 1973.
Ap. J., 184, 735, 1973.
Ap. J., 190, 283, 1974.
Ap. J., 194, 257, 1974.
IAU Symp. No. 38, 42-61, 1970.
Tartu Obs. Publ. No. 26, 23, 1970.
P.A.S.P., 86, 861, 1974.
Mass Determination and Models:
Astrofizika, 4, 364, 1968.
Astrofizika, 5, 317, 1969.
Astrofizika, 6, 149, 1970.
Astrofizika, 6, 241, 1970.
Kinematics:
Tartu Obs. Publ. No. 36, 55, 1972.
IAU Symp. No. 44, 37, 1972.
HII Regions:
Ap. J., 139, 1027, 1964.
Ap. J., 159, 379, 1970.
Ap. J., 163, 431, 1971.
Ap. J., 179, 445, 1973.
At 10 and 20 microns:
Ap. J. (Letters), 193, L7, 1974.
Radio Observations:
IAU Symp. No. 60, 229, 1974.
Interferometry: (H{Alpha})
Astr. Ap., 1, 208, 1969.
IAU Symp. No. 60, 229, 1974.
SN1885A: Search at 2695 Mhz,
Bull. A.A.S., 5, 322, 1973.
HI 21cm:
A.N., 288, 19, 1964.
A.J., 70, 669, 1965.
Ap. J., 141, 750, 1965
Ap. J., 144, 639, 1966
Ap. J., 175, 347, 1972.
Science, 153, 411, 1966.
M.N.R.A.S., 133, 359, 1966
M.N.R.A.S., 149, 237, 1970
M.N.R.A.S., 165, 9P, 1963
M.N.R.A.S., 169, 607, 1974.
Mem. R.A.S., 74, 43, 1970.
Astrophys. Lett., 4, 47, 1969.
IAU Symp. No. 44, 12, 1972.
Astr. Ap. Suppl., 12, No. 12, 1973.
Astr. Ap., 30, 353, 1974.
Companion at 1.5 degrees,
IAU Symp. No. 58, 122, 1974.
Radio Observations:
Ann. Ap., 26, 343, 1963.
Nature, 198, 844, 1963
Nature, 202, 269, 1964
Nature, 202, 1202, 1964
Nature, 207, 587, 1965
Nature, 214, 1190, 1967.
A.J., 69, 374, 1964
A.J., 70, 324, 1965.
A.J., 72, 809, 1967
A.J., 77, 637, 1972.
Science, 145, 389, 1964
Science, 156, 1087, 1967.
Observatory, 85, 24, 1965.
Ap. J., 142, 1333, 1965.
Bull. A.A.S., 3, 445, 1971.
Bull. A.A.S., 5, 29, 1973.
Astr. Ap., 34, 173, 1974.
X-Rays:
Ap. J., 179, 375, 1973
Ap. J., 190, 285, 1974.

18. 1973UGC...C...0000N
Re:UGC 00454
The Andromeda Nebula, brightest in Local Group
SA(s)b (de Vaucouleurs), Sb- (Holmberg)
Companions UGC 00426 = NGC 205 at 37, 314 and UGC 00452 = NGC 221 at 24, 181
SN 1885
Possible SN 1664b (?), 1898 (probably nova), 1919 (probably nova)

19. 1964RC1...C...0000d
Re:NGC 0224
= Messier 031
Brightest galaxy in the M31 (Local) Group.
Photograph:
Ap. J., 76, 44, 1932.
Ritchey, L'Evolution de L'Astrophotographie...,
S.A.F., Paris, 1929.
Monograph:
Ap. J., 69, 103, 1929. (= MWC 376).
Ap. J., 76, 44, 1932. (= MWC 452).
Ap. J., 100, 137, 1944 (=MWC 696).
Ap. J., 101, 179, 1945.
Ap. J., 102, 377, 1945.
Stockholm Ann., 19, No.2, 1956.
P.A.S.P., 50, 99, 1938.
Photometry:
M.N.R.A.S., 74, 132, 1913.
M.N.R.A.S., 87, 112, 1926.
M.N.R.A.S., 94, 805, 1934.
M.N.R.A.S., 97, 416, 1937.
M.N.R.A.S., 110, 416, 1950.
P.N.A.S., 20, 93, 1934.
Publ. Michigan, VIII, No. 7, 103, 1941.
Stockholm Ann., 13, 10, 1941.
Stockholm Ann., 19, 2, 1956.
Medd. Lund II, 128, 1950.
Medd. Lund II, 137, 1959.
Ap. J., 50, 384, 1919.
Ap. J., 83, 424, 1936.
Ap. J., 108, 413, 1948.
Ap. J., 128, 465, 1958.
Ap. J., 133, 309, 1961.
Zeit. fur Ap., 34, 137, 1954.
Zeit. fur Ap., 56, 194, 1962.
Izv. Pulkovo, 20, No. 156, 87, 1956.
Sov. A.J., 32, 16, 1955.
L'Astronomie, 76, 359, 1962.
Ap. J., 138, 1317, 1963.
Orientation:
P.A.S.P., 54, 72, 1942.
Ap. J., 104, 220, 1946.
Spectrum:
Ap. J., 88, 605, 1938.
Ap. J., 108, 415, 1948.
Ap. J., 135, 725, 1962.
P.A.S.P., 48, 17, 1936.
P.A.S.P., 69, 293, 1957.
P.A.S.P., 72, 76, 1960.
Lick Obs. Bull., 19, 498, 41, 1939.
A.J., 61, 97, 1956.
Polarization:
Stockholm Ann., 14, No.4, 1942.
Bull. Abastumani, No.18, 15, 1955.
Rotation and Mass:
Ap. J., 55, 406, 1922.
Ap. J., 95, 24, 1942.
Ap. J., 97, 112, 1943.
Ap. J., 136, 352, 1962.
P.N.A.S., 4, 21, 1918.
P.A.S.P., 50, 174, 1938.
P.A.S.P., 53, 270, 1941.
P.A.S.P., 72, 76, 1960.
Lick Obs. Bull., 19, 498, 41, 1939.
Zeit. fur Ap., 35, 159, 1954.
B.A.N., 14, 17, 1957.
A.J., 59, 273, 1954.
HII Regions:
Observatory, 79, 54, 1959.
Zeit. fur Ap., 50, 168, 1960.
SN 1885
Ap. J., 83, 245, 1936.
Ap. J., 88, 289, 1938.
Ap. J., 89, 141, 1939.
HI Emission:
B.A.N., 14, 1, 1957.
Radio Emission:
M.N.R.A.S., 110, 508, 1950.
M.N.R.A.S., 111, 357, 1951.
M.N.R.A.S., 119, 297, 1959.
M.N.R.A.S., 121, 413, 1960.
M.N.R.A.S., 122, 479, 1961.
Nature, 174, 320, 1954.
Nature, 175, 202, 1955.
Nature, 180, 60, 1957.
Nature, 183, 1251, 1959.
Ap. J., 126, 585, 1957.
A.J., 67, 580, 1962.
A.J., 68, 70, 1963.
A.J., 68, 274, 1963.

20. 1961Hubbl.B...0000S
Re:NGC 0224
MESSIER 031
Sb
PS-0-H
48" Schmidt
Sept. 29/30, 1948
103aO
10 min
Enlarged 2.5X
M31 is probably of the NGC 2841 type of multiple-arm galaxy
although it differs from such type examples as NGC 0488, NGC 5055,
and NGC 4699. The arms in M31 are thicker and less well
defined than in these prototypes. Baade has made a long
and careful study of M31, both of its geometric form and
of its stellar content. A short description of part of this
work is given by Baade in his report to the Rome
Conference on Stellar Populations (vol. 5 of Ricerche
Astronomiche, Specola Vaticana, 1958, pp. 3-21). Baade has
noted seven distinct spiral arms in M31 (see Table 2 of his
report). The inner two arms are dust arms; the outer five
arms contain supergiant O and B stars. The first two arms
cross the north-following half of the major axis at distances
of 3.4 and 8.0 sec of arc from the center. These
angles correspond to 1.5 mm and 3.6 mm from the center
on the scale of the illustration. Both arms, designated as
N1 and N2 by Baade, are within the burned-out central
region of the illustration.
The texture of the background luminosity of the central
portion of M31 is smooth and amorphous on plates
taken with small telescopes. Baade has shown, however,
that this central region can be resolved into red stars
whose color indices are about international 1.3 and whose
absolute magnitudes are about Mv = -3.0 (Baade, Ap. J.,
100, 79, 1944). The resolved images resemble those in
NGC 0205, which is the E5 companion galaxy west of the
center of M31. NGC 0205 is illustrated on page 3 of this
Atlas.
Dust lanes and dust patches are present in the central
region of M31. Again, these are not visible on the illustration.
But a negative print of lower intensity is reproduced
by Hubble and Sandage in Ap. J., 118, 353, 1953 (Fig. 2).
The dust arms and patches are similar to those in NGC 3031
(M81) shown on page 19 of this Atlas.
The distance modulus of M31 is probably close to
(m-M) = 24.6 (Th. Schmidt, Z. Astrophys., 41, 182, 1957;
Sandage, Ap. J., 127, 513, 1958). The limiting photographic
magnitude of the 48-inch Schmidt telescope is
m(pg) = 21.1 (Abell, Ap. J., Suppl. Sec., III, 211, 1958).
Therefore all resolved stars on this illustration are
brighter than M(pg) = -3.5.

21. 1961AJ.....66..541B
Re:NGC 0224
1. Local Group
Membership and velocities in the local group of galaxies have been discussed by
Humason and Wahlquist (1955). Clearly the bulk of the mass of the group is
contributed by NGC 224 and our Galaxy. Humason and Wahlquist pointed out that in
using the virial theorem the numerical values are very sensitive to the value of
the velocity of the center of the galaxy relative to the local group, which
depends on the velocity of rotation of the sun relative to the center. Kahn and
Woltjer (1959) used a value of 216 km/sec for the circular velocity of the sun
and concluded that unless the volume of the group was filled with intergalactic
matter to provide the large part of the total mass, the group would be unstable.
Godfredson (1961) reanalyzed the same data and showed that for a circular
velocity of 260 km/sec at the sun, the local group could be stable without
intergalactic matter being present. Thus the result is inconclusive.

22. 1956AJ.....61...97H
Re:NGC 0224
HMS Note No. 006
Nucleus, drifted length of slit for all plates.
HMS Note No. 007
On major axis, 14.0 arcmin south preceding nucleus.
Absorption lines in unresolved nebulosity.

23. 1918PLicO..13....9C
Re:NGC 0224
The Great Nebula in Andromeda, Vol. VIII, Plate 1. This wonderful object, the
largest of the spiral nebulae, is too well known to need description. Expo-
sures of 1m to 3m on S23 show an almost stellar nucleus, with traces of
spiral structure in the surrounding nebular matter. See Abs. Eff.


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