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Notes for object MESSIER 094

37 note(s) found in NED.


1. 2012ApJ...754...67F
Re:NGC 4736
NGC 4736 RSAR2..-Hosts a nuclear bar (Sakamoto et al. 1999) and prominent
nuclear spiral which extends all the way into the center in HST F555W. The bulge
is classified as pseudobulge by Fisher & Drory (2010). The obtained kinematic
data extend well into the disk. The rotational velocity flattens out abruptly at
about the bulge radius of 14.2" and shows a shallow negative gradient out to
about 70" where our data points start to become sparse. The velocity dispersion
rises abruptly from about 75 km s^-1^ to 115 km s^-1^ at about the bulge radius.
Well within the disk at radii larger than 50" we see again a gradual increase of
velocity dispersion. Inside of 2.5" the velocity dispersion exhibits a central
drop. The h_3_ moments are anti-correlated with velocity but show s-shape around
the center. They reach exceptionally large values of +/-0.2 at the bulge radius.
The h_4_ moments are compatible with zero in the inner bulge but reach
pronounced local maxima of values as large as 0.25 at about the bulge radius.
They fall off to zero at r ~= 35". These strong higher moments are a consequence
of the multicomponent structure of the LOSVDs at the respective radii (see
Section 5.7). The minor axis profile reflects the rich structure seen in the
major axis profile. The velocity dispersion rises significantly inward of 10".
The h_3_ moments are mostly compatible with zero at all radii, h_4_ moments are
zero inside of 10" but rise to about 0.1 at 20".

2. 2011AJ....141...23B
Re:NGC 4736
A.16. NGC 4736
NGC 4736 is a ringed spiral galaxy located at D = 4.7 Mpc
in which we encountered 23 holes in its HI distribution. The
range of their diameters is quite small (0.21-0.45 kpc) and they
are young holes (t_kin_ < 22 Myr). As panel (C22) in the online
version of Figure 30 illustrates, the majority of the holes are
located at small galactocentric radii and only type 1 holes lie at
larger galactocentric radii. Finally, note that hole number 11 is
probably a superposition of two holes.

3. 2009ApJ...697.1870E
Re:NGC 4736
NGC 4736 (M 94) Though we were able to measure eight offsets at r = 1-1.5 kpc
(0.7'-1.0'), which are clear in the CO and H{alpha} images, they show a negative
dependence on {OMEGA}. We derived the rotational velocity from CO data, but it
was not consistent with the RC from Sofue et al. (1999) at where we measured
offsets. Given that the RC from Sofue et al. (1999) is flat, which is typical of
spiral galaxies, we use this to calculate {OMEGA}. However, even if we used the
RC from CO data, the dependence of offsets on {OMEGA} would still be negative.
NGC 4736 is the only galaxy in our sample to be classified as flocculent (AC
= 3). A star-forming ring or short spiral arms are apparent at r ~ 1-1.5 kpc in
the H{alpha} image, while molecular arms are longer and apparent at r ~ 1-2 kpc.
This difference in morphology between CO and H{alpha}, which has been also noted
by Wong & Blitz (2000), could be responsible for the negative correlation
between {theta} and {OMEGA}. Therefore, we deduce that there are other triggers
of star formation than the spiral density wave in this galaxy.
One possible trigger is an expanding poststarburst ring, proposed by van der
Kruit (1974) and Sanders & Bania (1976). They explained that the ring resulted
from a central starburst which occurred about 10 Myr ago, from spectroscopic
observations and hydrodynamical calculations. Maoz et al. (1995) found two
compact UV sources separated by 2.5" in the nucleus with diffuse emission
centered on the one source, presumably corresponding to the optical nucleus.
They interpreted their results to be the final stage of a merger, which is
consistent with the poststarburst scenario. Munoz-Tunon et al. (2004) adopted
another possibility of this ring to be located at the OLR of the central bar as
well as the ILR of the outer disk. The pattern speed for each structure should
be 85 and 27 km s^-1^ kpc^-1^, respectively, and the latter could explain the
location of outer faint ring at r ~ 5'. They also noted that the FUV ring is
located slightly outward from the H{alpha} ring, implying an inward-propagating
star formation, which is
Rand & Wallin (2004) applied totally opposite with the poststarburst
scenario. the TW method to BIMA CO data, and derived {OMEGA}_P_ = 152 +/- 28 km
s^-1^ kpc^-1^, corrected for our distance. This value is much larger than that
derived by Munoz-Tunon et al. (2004), and locates the corotation at r =
0.8'-1.2', which is almost same as where we measure the offsets.

4. 2009A&A...503..409H
Re:NGC 4736
NGC 4736(M94): The polarized emission in this galaxy is seen from both the inner
star-forming disk and also concentrated along the minor axis, particularly in
the form of a possible polarized lobe directed toward the southwest. Within the
central disk, the polarized intensity declines to a minimum in the direction of
the receding major axis (PA = 296^deg^, as tabulated in Table 1). The central
source is polarized at about the 2% level. The inner ring is polarized on the
south side, at about the same fraction. The polarized fraction increases at
large radii up to about 40%. Magnetic field lines in the possible lobe structure
are aligned radially away from the nucleus. Since the near-side of the stellar
disk in this system (as determined from optical dust lanes) is in the northeast,
the location of the southwestern lobe is consistent with it being the closer of
a pair of symmetric nuclear outflows, in which the more distant lobe suffers
greater depolarization from the intervening disk. This, together with the lack
of a conspicuously distinct feature in the Stokes I map at the same location,
points to the lobe structure being intrinsic to NGC 4736 (as opposed to an
extended, polarized, background source). Galactic foreground RM in the field can
be estimated from several double sources which are detected in polarization. Two
of these are rather faint and have large uncertainty, while the high
signal-to-noise detection yields a value of +1 +/- 1 rad m^-2^. A very extended
(6 arcmin) background double radio galaxy is also seen in the southwest portion
of the field. Although both lobes have similar brightness in both I and P, the
polarized surface brightness is so faint that an accurate RM determination is
not practical.

5. 2008MNRAS.385..553D
Re:NGC 4736
NGC 4736 (M94): This ringed galaxy exhibits a bright inner ring with a
nearly constant rotational velocity of about 195 km s^-1^. The
dispersion velocities are typical of those seen in H II regions. The
location of this H{alpha} ring is consistent with resonances caused by
the bar and by a larger oval distortion. CO observations reveal tightly
wound spiral arms separated by a small nuclear bar that is perpendicular
to the major axis PA of the galaxy (Helfer et al. 2003) as well as gas
moving on elliptical orbits around the nuclear bar. Modelling of
H{alpha} and CO kinematics shows an inflow of material near the ends of
the nuclear bar, an outflow between the bar and the ring, and an inflow
of gas just outside the ring (Wong & Blitz 2000; Munoz-Tunon, Caon &
Aguerri 2004). The slightly declining H{alpha} rotation curve presented
in this paper is consistent with CO and H I observations, but not in the
central regions.

6. 2008AJ....136.2648D
Re:NGC 4736
4.11. NGC 4736 was previously observed in H I by Mulder (1995) who also derived
a rotation curve. Figure 14 shows a comparison between the respective rotation
curves. Due to the lower resolution and sensitivity of his data, Mulder (1995)
did not detect a trend of inclination with radius, and therefore assumed a
constant value of 40{degree}. In Figure 14 we therefore also show his rotation
curve corrected using our inclination values. Although the large-scale trends
are similar to those found for our curve, the THINGS curve, in general, shows
more pronounced small-scale features.

7. 2008AJ....136.2648D
Re:NGC 4736
6.10. NGC 4736 The surface brightness profiles of NGC 4736 are shown in Figure
43. The 2MASS J, H, and K profiles can be traced out to ~250", whereas the 3.6
{mu}m profile can be traced out to the edge of the H i disk at ~400". The
stellar component of NGC 4736 has a complex structure. A prominent stellar ring
can be seen in various wavelengths at a radius R ~ 40". The ring, visible in the
3.6 {mu}m image, is also prominently visible in the 20 cm radio continuum. The
presence of this fairly strong continuum suggests active star formation and may
mean that at this particular radius the assumption that the 3.6 {mu}m emission
is proportional to the stellar mass is not valid. For this reason, we will not
take this feature into account in our subsequent analysis of the surface
brightness profile. The IRAC 3.6 {mu}m profile flattens out at 250" <~ R
<~ 400", caused by the faint stellar ring surrounding the main body of NGC
4736. At larger radii (beyond the edge of the H i disk) the profile starts
decreasing again. Also visible is a significant steepening in the inner parts.
We will treat this as evidence for a separate central component with parameters
{mu}_0_ = 11.8 mag arcsec^-2^ and h = 0.26 kpc. To model the outer disk, we
fitted an exponential disk to the radial range 80" < R < 240" and found
parameters {mu}_0_ = 15.9 mag arcsec^-2^ and h = 1.99 kpc. We used the
extrapolated fit for radii R < 80" and the observed radial surface brightness
for R > 80". NGC 4736 exhibits a small color gradient in the outer parts with a
steeper inner reddening. We have adopted a constant value of {GAMMA}^3.6^_*_ =
0.6 for the outer disk beyond the last reliable 2MASS (J - K) value, and have
additionally assumed a constant {GAMMA}^3.6^_*_ = 0.7 for the innermost 20". For
the central disk, we assume a constant {GAMMA}^3.6^_*_ = 0.9 which is the
average value for R > 20". The rotation curves are shown in Figure 44. It is
immediately obvious that NGC 4736 must be close to maximum disk. The predicted
{GAMMA}^3.6^_*_ value for the inner disk yields a curve that overestimates the
rotation velocity (not shown here). We therefore left {GAMMA}^3.6^_*_ of the
inner disk as a free parameter after fixing the {GAMMA}^3.6^_*_ value of the
main disk. This resulted in an inner disk mass of about a factor of ~2 less than
predicted (and is the model shown in Figure 44). While the discrepancies are
slightly less for the Kroupa {GAMMA}^3.6^_*_ values, the resulting models still
overpredict the rotation velocity. Because of these uncertainties and because of
the large noncircular motions in this galaxy (Trachternach et al. 2008), it is
virtually impossible to say anything definite about the distribution of dark
matter in this galaxy based purely on rotation curve arguments.

8. 2007MNRAS.382.1552L
Re:NGC 4736
NGC 4736 - M 94: HST UV imaging of this galaxy shows two equally bright compact
nuclear sources separated by 2.5 arcsec in the north-south direction (Maoz et
al. 1995). The southernmost source corresponds to the nucleus and is also
detected as a high brightness temperature compact radio source (Turner & Ho
1994) and in X-rays (Pellegrini et al. 2002). The nucleus of this galaxy is
classified as a LINER and is a strong and complex X-ray source from point
sources and extended emission (Paper I; Eracleous et al. 2002). The large B/I
image in Fig. 2 shows a blue star-forming ring and associated radio emission
from the FIRST survey. Red arcs are seen in the inner disc as well as a nuclear
minibar (length ~=20 arcsec), which causes the central surface brightness
contours to be elliptical. The colour structure in the nucleus of the galaxy is
probably an artefact due to slightly different point spread functions (PSFs) in
the two images.

9. 2007MNRAS.377.1696M
Re:NGC 4736
NGC 4736. VLA measurements with a resolution of 0.15 arcsec reveal an unresolved
nuclear source with a flux of 1.7 mJy at 2 cm (Nagar, Falcke & Wilson 2005). At
3.5 cm, with a resolution of 0.24 arcsec, Kording, Colbert & Falcke (2005) also
find a flux of 1.7 mJy.
Maoz et al. (1996) used the HST/FOC in 1993 to measure a 2300-AA flux of 19 *
10^-17^ erg cm^-2^ s^-1^ A^-1^. M05 reported that, in the ACS F250W band in
2003, the nucleus was significantly brighter than that in 1993, at 48 * 10^-17^
erg cm^-2^ s^-1^ A^-1^. However, reanalysis of the M05 images raises some
doubts. The nuclear source in this galaxy is superimposed on a fairly bright
diffuse stellar background, and the nuclear flux is sensitive to the aperture
used for the measurement. Compared to the FOC F220W image, the stellar
background is more prominent in the redder F250W measurement by M05 which, being
a CCD observation, is also more susceptible to red leak. Photometry of the M05
data using an aperture smaller than that used by M05 (and smaller than the
minimum that M05 found was required to provide reliable photometry in these ACS
data) gives a value closer to the 1993 level. On the other hand, the 1993 FOC
data were affected by non-linearity and satur ation, both of which would lead to
an underestimate of the true flux. Given these uncertainties, I will adopt the
mean level between these measurements, 39 * 10^-17^ erg cm^-2^ s^-1^ A^-1^ for
the 2500-A flux, and the M05 value at 3300 A, 73 * 10^-17^ erg cm^-2^ s^-1^
A^-1^. The UV variability amplitude during the M05 campaign was only 5 per cent
at 2500 A, and null at 3300 A, providing a weak lower limit on the AGN flux.
In Chandra X-ray images obtained by Eracleous et al. (2002), the unresolved
nuclear source (X-2 in their table 4) has a 2-10 keV flux of 27 * 10^-14^
erg cm^-2^ s^-1^ at 2-10 keV and a photon index of 1.6.

10. 2007A&A...461.1209D
Re:MESSIER 094
M 94: The BeppoSAX data were published in Pellegrini et al. (2002). The
spectral parameters reported here are in agreement, within a 90%
confidence level, with what was previously published. A marginal
(confidence level ~99% accordingly to F-test) detection of the
FeK{alpha} line at E=6.7 +/- 0.3 keV is also reported here.

11. 2006ApJ...638..642B
Re:NGC 4736
NGC 4736 - Several sources may have been marginally suspected in the
INTEGRAL data. They either were targets of dedicated observations or were
detected in some single science windows. We performed the same analysis as
for the other sources presented here, but found only spurious source
candidates that result from image reconstruction problems such as ghosts
and mask patterns. Among those sources are Mrk 231, ESO 33-2, PKS 0637-75,
MCG -05-23-16, QSO 1028+313, NGC 4736, NGC 4418, 3C 353, and QSO
1730-130.8

12. 2006A&A...460...45G
Re:NGC 4736
NGC 4736 (M 94, UGC 7996). This galaxy shows a large amount of unresolved
compact sources in the few central arcseconds, which make the extraction of the
true nuclear source rather difficult (Fig. 5). Eracleous et al. (2002)
identified 3 sources in the nuclear region, all of them showing hard spectra
with power law indices ranging from 1.13, for the brightest one, to 1.8 for X-3,
and luminosities in the 2-10 keV band between 4 x 10^38^ erg s^-1^ and 9.1 x
10^39^ erg s^-1^. We identified the source X-2 by Eracleous as the nucleus of
the galaxy since it coincides with the 2MASS near-IR nucleus within 0.82".
Eracleous (2002) points out the complications of defining an AGN or SB character
to this source, suggesting that even if the brightest source is associated with
an AGN it will only contribute 20% to the energy balance in the X-rays. The
radio monitoring observations made by Kording et al. (2005) with the VLBI found
a double structure, and the radio position N4736-b coincides with our identified
X-ray nucleus. From this double structure the brightest knot N4736-b also
appears to be variable, pointing to an AGN nature for this low luminosity AGN.

13. 2004A&A...415..941E
Re:NGC 4736
NGC 4736 (M 94): Shaw et al. (1993) and Mollenhoff et al. (1995). As
with NGC 1068, the outer bar is rather weak, and has been termed an
"oval disk" rather than a bar. However, there is ample kinematic
evidence that it rotates and behaves dynamically like a bar (e.g.,
Mollenhoff et al. 1995; van Driel et al. 1996, and references
therein). Outer disk PA is from the kinematics and modeling of
Mollenhoff et al. and van Driel et al., with inclination being the
average of photometric and kinematic inclinations from those studies and
the H I observations of Mulder & van Driel (1993). Distance is from
Tonry et al. (2001, surface-brightness fluctuation).

14. 2003A&A...398..467K
Re:NGC 4736
NGC 4736 = M 94. NGC 4736 is the brightest galaxy of type Sa in CVn I.
We resolve it into stars for the first time. The WFPC2 was pointed at
the galaxy periphery to avoid stellar crowding. In the galaxy halo the
CM diagram (Fig. 2) shows numerous RGB stars with I(TRGB) = 24.33 +-
0.28 mag, which yields a distance of 4.66 +- 0.59 Mpc. Karachentseva &
Karachentsev (1998) carried out a proper search for dwarf companions
to NGC 4736 based on the POSS-II plates. Surprisingly, they found no
companions with a central surface brightness brighter than
25^m^/square " in the B band within a radius of ~3 degrees or 230 kpc
around this giant galaxy. Such a pronounced degree of isolation of an
Sa galaxy situated in the middle of the CVn I cloud seems rather
unusual.

15. 2002PNAOJ...6..107M
Re:KUG 1248+413
Many blue knots on the ring.

16. 2002ApJS..139....1T
Re:NGC 4736
NGC 4736 (L2).-ASCA and ROSAT results are given by Roberts, Warwick, &
Ohashi (1999) and Roberts et al. (2001). They reported a marginal
detection of an ionized Fe K emission line. We found a possible hint of
Fe K emission in the ASCA spectrum, although the equivalent width in our
fit is lower than previously obtained. The line center energy is
consistent with a He-like ionization state for Fe, but neutral Fe cannot
be ruled out. Very extended emission is seen in the ROSAT HRI image (Cui,
Feldkhun, & Braun 1997; Halderson et al. 2001). There are several bright
X-ray sources in an archival Chandra image of the nuclear region. The
ASCA flux is the superposition of these sources and is not dominated by
the nucleus.

17. 2002AJ....124..675C
Re:UGC 07996
Very large galaxy. The NVSS flux density may be too low.

18. 2002A&A...389...68G
Re:NGC 4736
NGC 4736: for this galaxy, we have two catalogs. In both cases,
nearly all the HII regions are placed in the external ring. Our
four results are only in rough agreement and they are,
furthermore, not very reliable since they pertain to the ring.
Thus, we prefer to adopt, the mean values given from the
velocity fields (Bosma et al. 1977; Mulder & van Driel 1993;
Buta 1988) which are in good agreement between them and also
with the average of our two methods and the two catalogs.

19. 2001MNRAS.324..737R
Re:NGC 4736
A6 NGC 4736
NGC 4736 (M94) hosts the closest example of a LINER 2 nucleus, and so is
amongst the best studied. There is conflicting evidence as to whether the
LINER 2 in NGC 4736 is powered by a LLAGN. Larkin et al. (1998) conducted
a near-infrared spectroscopic survey of LINER galaxies and found NGC 4736
to have the largest [Fe II]/Pa{beta} ratio in their sample, indicating
that its excitation was dominated by stellar processes. Both the H{alpha}
luminosity (Taniguchi et al. 1996) and FIR emission (Smith et al. 1991;
Smith et al. 1994) may also be explained solely by stellar emission. On
the other hand, Turner & Ho (1994) detect a strong non-thermal radio
continuum source at the position of the nucleus. Maoz et al. (1995) image
the nucleus in UV using the HST, and detect two bright point sources in
the nuclear region and possible bow shocks, leading to the conjecture that
two objects are in the final stages of merging in the nucleus. One or both
of these sources may be very compact star clusters, but they may also be
supermassive black holes, one of which comes from a merged, nucleated
satellite galaxy (as postulated in Taniguchi & Wada 1996).
Cui, Feldkhun & Braun (1997) studied a ROSAT PSPC observation of
NGC 4736 which revealed a bright, nuclear X-ray source surrounded by an
extended region of soft (kT ~ 0.3 keV) thermal gas. The PSPC data was
re-analysed, along with two ROSAT HRI observations and an ASCA observation
of the galaxy, by Roberts, Warwick & Ohashi (1999). They found the X-ray
spectrum to be dominated by a Seyfert-like power-law continuum with slope
{GAMMA} ~ 1.7, with little intrinsic absorption. Below 2 keV two thermal
emission components were required with kT in the range 0.1-0.6 keV. The
possible detection of an Fe K{alpha} feature at 6.8 keV was also reported.
The compact nuclear source was found to have a luminosity of
6 x 10^39^ erg s^-1^ (0.5-10 keV) and thus may be a near-quiescent AGN.
However, the alternative hypothesis that the hard component originates
entirely in X-ray binaries could not be ruled out.

20. 2001AJ....122..637H
Re:NGC 4736
NGC 4736. - A two-component model similar to ours, consisting of a
power law and a Raymond-Smith plasma, was favored by Cui, Feldkhun, & Braun
(1997). Significant deviation at the low-energy end of the spectrum
necessitated the addition of a Gaussian line feature centered at 0.22 keV.
Altering elemental abundances and experimenting with more complicated
models failed to improve the low-energy fit, so they suggested that the
Gaussian component may be a calibration artifact. They derived an observed
0.1-2.0 keV flux of 1.78 x 10^-12^ ergs cm^-2^ s^-1^, which is very close
to our observed flux before we attempted to minimize the included flux due
to extended emission. Again, we have attempted to estimate only the flux
arising from a point source, so we expect that our value is closer to the
flux produced by the nucleus itself.

21. 2000MNRAS.319...17L
Re:NGC 4736
NGC 4736 (M 94): Strong X-ray emission is associated with the LINER nucleus
of this galaxy. An extended nuclear source can be seen in Fig. 22. The
azimuthally averaged profile of this source and the HRI model PSF are shown
in Fig. 34.
The galaxy was previously imaged with the Einstein HRI. A nuclear flux
of 2.0 x 10^-12^ erg s^-1^ cm^-2^ was measured within an aperture of
60-arcsec radius in the 0.5-4.0 keV bandpass (Fabbiano et al. 1992). The
fluxes measured from the ROSAT HRI observation using a small
(r = 10 arcsec) and a large aperture (r = 100 arcsec) are
1.4 x 10^-12^ and 4.7 x 10^-12^ erg s^-1^ cm^-2^ respectively (see
Table 4). Since the emission is highly concentrated towards the nucleus,
the difference between the 60-arcsec Einstein and 100-arcsec ROSAT fluxes
cannot be explained by the different aperture sizes alone. The change in
the total observed flux could be explained, however, if the central source
is variable, or if a substantial fraction of the emission is radiated in
the very soft X-rays (kT <~ 0.5 keV). Roberts, Warwick & Ohashi (1999)
have recently reported on ASCA and ROSAT PSPC and HRI observations for
NGC 4736. They find that the nuclear emission is consistent with an
unresolved source plus an extended component. PSF modelling shows that the
unresolved source accounts for more than 50 per cent of the detected
emission (Roberts et al. 1999). The 0.1-10 keV ASCA spectrum of the
emission is consistent with a power law with index {alpha} ~ 1, plus a
softer thermal component (kT ~ 0.1-0.6 keV) which dominates below 2 keV.

22. 2000ApJ...534..670T
Re:NGC 4736
NGC 4736.-The luminosity profile is obtained only in the bulge region.
The M/L in the bulge region decreases distinctly inward by 0.38 times
from r = 1.8 kpc to 800 pc. The M/L in the innermost region cannot be
evaluated because of the large spatial resolution.

23. 2000ApJ...530..688A
Re:NGC 4736
NGC 4736 (M94).-This true LINER, according to Heckman's (1980)
definition, is an interesting example that suggests a combination of
excitation mechanisms. The stellar continuum subtracted optical spectrum
shows characteristics of a transition object (Ho et al. 1995), or type 2
LINER (Ho et al. 1997a), rather than a classical LINER. It does not show
a broad component of H{alpha} (Ho et al. 1997c). This LINER has strong
Balmer optical and infrared absorptions (e.g., Larkin et al. 1998) and
other characteristics that make it the prototype of a late-phase
starburst (e.g., Walker et al. 1988; Taniguchi et al. 1996), but also
has a compact X-ray source possible indicative of a weak AGN
(Cui, Feldkuhn, & Braun 1997). The high value of the
[Fe II] 1.257 micron/Pa{beta} line ratio (Larkin et al. 1998) confirms
the presence of an evolved starburst in which the SNRs have a dominant
contribution.

24. 1999ApJS..124..403S
Re:NGC 4736
5.12. NGC 4736
NGC 4736 is an early-type spiral galaxy with a poststarburst
nucleus (Walker, Lebofsky, & Rieke 1988; Taniguchi et al. 1996). We
present two sets of maps; one for the central 1' and the other for the
2.4' x 1' region along the major axis mosaicked at a lower resolution.
The CO emission peaks toward the galactic center, suggesting that the
poststarburst nucleus had stopped star formation before using up
molecular gas or the gas has been replenished after the starburst.
The central CO condensation of a diameter about 6" (120 pc) is
resolved to two peaks separated by 3" (60 pc) in the higher resolution
map. The separation and position angle of the two peaks agree with those
of the main (south) and secondary (north) UV sources detected by Maoz
et al. (1995). The southern peak is brighter both in CO and UV, though
the identification of the peaks in the two bands is not firmly
established because of the lack of absolute positions in the UV data.
The central CO concentration with the twin peaks is in a CO bar that has
a position angle of ~ 45^deg^ and a projected length of 25". There is a
nuclear stellar bar of the same length (Mollenhoff, Matthias, & Gerhard
1995), but it has about 20^deg^ less position angle (i.e., the molecular
bar follows the stellar bar for the clockwise rotation of this galaxy).
Judging from the gas morphology, it may be that the two peaks in the
nuclear concentration are the twin-peak structure at the ILR of the
nuclear bar. The misalignment between the stellar and molecular bar is
unusual in that case. Alternatively, NGC 4736 may have experienced a
minor merger with the two nuclei being seen as the two UV sources
(Maoz et al. 1995). The nuclear source of radio continuum with a size of
0.6" (Turner & Ho 1994) is within 1" of the southern CO peak. Velocity
field within 5" of the continuum source appears symmetric about the
radio source, implying the nuclear source being at the dynamical center.
However, large noncircular motions and asymmetric gas distribution in
the surrounding regions make it difficult to accurately determine the
dynamical center from the global velocity field. Even if the secondary
UV source is a nucleus of a merging galaxy, molecular gas at the
secondary (northern) peak is not kinematically decoupled from the rest
of the galaxy, which is reasonable because gas should merge faster than
stars.

25. 1999ApJS..124..403S
Re:NGC 4736
There are multiple arms and arcs outside the nuclear bar. A pair of
molecular arcs extends from the ends of the nuclear bar mostly to east
but partly to west. Prominent noncircular motions are seen on the
molecular arcs. There is another arc of molecular gas to the west of the
nucleus at r ~ 20", which lacks a counterpart on the opposite side of
the nucleus. These molecular arcs are seen in absorption (i.e.,
reddening) in the optical and near-IR color index maps (Beckman et al.
1991; Block et al. 1994; Mollenhoff et al. 1995). There is a pair of
molecular gas arcs at a radius of ~ 40", which has been noticed from
lower resolution observations by Garman & Young (1986) and Gerin,
Casoli, & Combes (1991) and now clearly shows its spiral structure. The
molecular gas spirals are associated with the prominent spiral features
of star formation seen in H{alpha} and radio continuum (Pogge 1989;
Duric & Dittmar 1988). These arc features are consistent with the
observations by Wong, Helfer, & Blitz (1998). The multiple arc features
in this galaxy may be due to the combined action of the nuclear bar and
the oval distortion of the outer disk. The latter distortion also caused
the outer H I and stellar ring at ~ 5' radius (Mulder & van Driel 1993;
Gerin et al. 1991).

26. 1998ApJS..114...59L
Re:NGC 4736
NGC 4736.--This is a true LINER satisfying both of Heckman's (1980) criteria.
NGC 4736 is one of the strongest continuum sources in the sample, which makes
the weak lines difficult to detect. The [Fe II] to Pa{beta} ratio is the
highest of any object in this sample and the second largest of any
extragalactic object measured (only NGC 6240 has a higher ratio). However, this
ratio is uncertain by 50% owing to the strong continuum surrounding the [Fe II]
line and the strong Pa{beta} absorption. The ratio is supported by the strong
optical ratio of [O I]/H{lapha}, which, as discussed above, correlated with
[Fe II]/Pa{beta}. The H_2_/Br{gamma} is only a very poor upper limit, but,
based on the other two line ratios, it is probably also very high (~10). Like
NGC 404, NGC 4736 is very close (4.3 Mpc), which makes the [Fe II] luminosity
only a few times higher than an individual SNR. The estimated Pa{beta}
absorption in Table 3 is not sufficient to reconcile optical line strengths
and the observed Pa{beta} flux. This may indicate the presence of a younger
stellar population. Atomic absorption features are strong in the infrared
spectra and in the optical spectra of Filippenko & Sargent (1985). NGC 4736 was
found by HST to have two compact UV sources separated by 2.5" in its nucleus
(Maoz et al. 1995). It also had UV arcs at 2", 4", and 6", which is suggestive
of bow shocks. At much larger scales, NGC 4736 has a strong ring of H{alpha}
emission (Larkin et al. 1998). All of these features suggest that NGC 4736 has
experienced recent star formation.

27. 1997ApJS..108..155G
Re:NGC 4736
NGC 4736 shows a bright H{alpha} ring in which we have detected 168 H II
regions. The nucleus has diffuse emission surrounding a brighter compact
source. A detailed analysis of the broadband emission has been published
by Beckman et al. (1991). Smith et al. (1991, 1994) study 50 and 100
micron images from the Kuiper Airborne Observatory.

28. 1995ApJS...98..477H
Re:NGC 4736
HST UV images reveal two unresolved point sources in the center of this
galaxy, as well as three arcs shaped like bow shocks, suggesting that the
system might be a merger remnant (Maoz et al. 1995). After careful
starlight subtraction, the emission-line intensity ratios resemble those
of ``transition objects'' (LINER/H II). The stellar component of the
photoionization probably comes from young stars formed as a result of the
merger.

29. 1994CAG1..B...0000S
Re:NGC 4736
Hubble Atlas, p. 16
RSab(s)
PH-423-MH
April 15/16, 1952
103aO
30 min
The print of NGC 4736 here, although made from the same plate
used in the Hubble Atlas, has been printed to a different contrast,
showing different features.
The description in the Hubble Atlas is still generally valid
except for the comment there that no spiral exists in the central
regions. Central spiral structure does exist; the tight arms are
smooth, with no evidence of recent star formation. (There are no
HII-region candidates in the innermost arms.)
The very large variation of the surface brightness across the
inner disk makes the photographic reproduction of the intricate
details of the inner arm structure and the nearly detached outer ring
(in which star formation is occurring) impossible to show adequately.
The outer ring is shown well in the Hubble Atlas insert
print. Its very low surface brightness is emphasized in the insert
print here, where it can be seen best by viewing from a distance and
moving the head and eyes. Note the absence of luminosity over most of
the area between the edge of the main body and the inner edge of this
outer ring. However, as seen in the Hubble Atlas and weakly here,
there is a faint attachment of this outer near-ring to the main body
on the left side of the major axis of the insert print here.

30. 1993ApJS...86....5K
Re:NGC 4736
NGC 4736 (M 94); SAab, LINER.
This galaxy has an expanding ring of H II regions surrounding the
nucleus. Studies of the H{alpha} emission from the ring (Buta 1988) and
the discovery of many discrete compact radio sources similar to those
found in M82 and NGC 253 (Duric & Dittmar 1988; Kronberg, Biermann, &
Schwab 1985; Antonucci & Ulvestad 1988), explained as bremsstrahlung from
H II regions and synchrotron radiation from supernova remnants, confirm
that the ring is the site of intense star formation activity. The ring is
50" from the nucleus, so that it falls outside the IUE aperture, and thus
the galaxy does not appear as a starburst in the UV.
Studies of the nucleus show that this object is relatively blue and has
an extremely high surface brightness (Keel & Weedman 1978). De Bruyn
(1977) has reported an extended (5") radio source centered on the
nucleus. The anomalous strength of the CO bands is explained by Walker,
Lebofsky, & Rieke (1988) as the result of a very powerful but not recent
starburst. The presence of a high percentage of stars as early as A4-A7,
as deduced by population synthesis models of the optical spectrum of
NGC 4736, is consistent with the picture of past starbursting activity,
although the weak lines and blue colors in the optical can be evidence
also for a metal-poor population with a hot blue horizontal branch
(Pritchet 1977). The presence of low-excitation emission lines led
Heckman (1980) and Keel (1983a, b) to classify this galaxy as a LINER.
The UV spectrum shows a forbidden emission line (C III] {lambda}1909) and
broad absorption features. The continuum is typical of an Sab galaxy.

31. 1976RC2...C...0000d
Re:NGC 4736
= M94
Photograph:
Astr. Ap., 15, 110, 1971.
IAU Symp. 44, p. 56, 1972.
IAU Symp. 58, p.431, 1974.
Ap. J., 147, 477, 1967.
Ap. J., 188, 3, 1974.
A.J., 72, 1032, 1967.
A.J., 72, 431, 1974.
Photometry (UBV):
Ap. J., 143, 187, 1966.
Ap. J., 147, 407, 1967.
A.J., 72, 1032, 1967.
Photometry (5 Color):
A.J., 73, 313, 1968.
Photometry (I.R., 1-20 microns):
Ap. J., 143, 187, 1966.
Ap. J. (Letters), 159, L165, 1970.
Ap. J. (Letters), 161, L203, 1970.
Ap. J. (Letters), 176, L95, 1972.
Spectrum:
Ap. J., 147, 407, 1967.
Ap. J., 188, 3, 1974.
Spectrophotometry (Far UV):
N.A.S.A., SP. 310, p.559, 1972.
Rotation Curve and Mass Determination:
J. Observateurs, 48, 247, 1965 = Publ.O.H.P., 8, No. 16
Ap. J., 147, 407, 1967.
Ap. J., 188, 3, 1974.
Astr. Ap., 8, 364, 1970.
IAU Symp. No.58, p.431, 1974.
HI 21cm:
Ap. J., 150, 8, 1967.
IAU Symp. No.58, p.408, 1974.
Radio Observations:
Astr. Ap., 15, 110, 1971.
Astr. Ap., 29, 231, 1973.
A.J., 78, 18, 1973.

32. 1973UGC...C...0000N
Re:UGC 07996
(R)SA(r)ab (de Vaucouleurs), Sb- (Holmberg)

33. 1964RC1...C...0000d
Re:NGC 4736
= Messier 094
Extremely bright nucleus in a bright (r): 1.6 arcmin x 1.2 arcmin. Very many
smooth arms in a lens: 6.0 arcmin x 4.7 arcmin. Faint (R): 11.2 arcmin x
8.5 arcmin.
Photograph:
Ap. J., 135, 366, 1962.
Handbuch der Ap., 5, 2, 843, 1933.
Photometry:
Ap. J., 46, 206, 1917.
Ap. J., 50, 384, 1919.
Ap. J., 83, 424, 1936.
Ap. J., 108, 415, 1948.
Spectrum:
Lick. Obs. Bull., 497, 1939.
IAU Symp. No. 5, 1958 = Lick Contr. II, No. 81, 1958.
Ap. J., 135, 698, 1962.
Ap. J., 135, 734, 1962.
Orientation, Rotation and Mass:
Ap. J., 127, 487, 1958.
Ap. J., 97, 117, 1943.
Ap. J., 135, 366, 1962.
HII Regions:
Zeit. fur Ap., 50, 168, 1960.
Radio Emission:
M.N.R.A.S., 122, 479, 1961.

34. 1961Hubbl.B...0000S
Re:NGC 4736
Messier 094
Sb
PH-423-MH
Apr. 15/16, 1952
103aO
30 min
Enlarged 3.2X
The range of surface brightness between the nuclear region
and the outer regions, including the external ring,
is very great. This illustration does not show the complex
structure of the galaxy. The intense central region is devoid
of spiral structure. It is 32 sec of arc in diameter
(8 mm on the illustration). Tightly wound spiral arms of
the kind seen in NGC 4699 (left) begin tangent to this
amorphous central region and wind out through a region
of lower surface brightness of lens shape with a diameter
of 120 sec of arc (35 mm on the illustration). Details of
structure in both these regions are invisible here because
of the inability of photographic paper to reproduce large
intensity differences. A third region, filled with spiral
arms, begins at the outer boundary of the second zone.
As between the first and second zones, a sharp discontinuity
of surface brightness exists between the second and
third zones. The spiral structure in the third zone is seen
in the illustration. The surface brightness of the third
zone appears to go to zero rather suddenly 200 sec of arc
from the center. An annular zone devoid of luminosity
then begins. This zone of near zero surface brightness
continues until the inner boundary of a faint external ring
is reached at 260 sec of arc radius from the nucleus. The
ring is shown in the insert. It has a fairly sharp inner
boundary but fades and is lost in the night-sky radiation
at large distances from the center. The ring is not
detached from the nuclear region but is connected to the
more central regions on the west side.

35. 1957HPh....53..275d
Re:NGC 4736
(R)SA(r)ab
(Plate 21)
(= Messier 094)
Only the complex spiarl pattern of high multiplicity in
the lens appears in this reproduction.
The small nucleus and inner ring (r) surrounding it are lost
in the over-exposed central bulge; the outer, smooth ring
structure (R) extending beyond the limits of the (Plate is not
shown either.
Compare with NGC 7702 (Plate 8), NGC 4569 (Plate 17)
and NGC 6753 (Plate 22).

36. 1956AJ.....61...97H
Re:NGC 4736
HMS Note No. 151
Nuclear region.
Redshift from absorption lines and {lambda} 3727.
HMS Note No. 152
Brighter part of spiral-arc ring 50 arcsec [north-west] of nucleus.
{lambda} 3727 and emission H{gamma} and H{beta},
which give velocities affected by rotation.
HMS Note No. 153
Fainter part of spiral-arc ring 60 arcsec [south-east] of nucleus.
Only {lambda} 3727, which gives an uncertain velocity
affected by rotation.

37. 1918PLicO..13....9C
Re:NGC 4736
Vol. VIII, Plates 43 and 44. M.94. A beautiful object. From the very bright,
large nucleus spring many bright, closely packed whorls, forming a bright
inner oval 2' x 1.5' in p.a. about 110^deg^. These inner whorls show many
stellar condensations, whose sharpness and proximity to the nucleus would seem
to make this one of the most favorable examples known for the investigation of
motion in spirals. Fainter, closely packed, rather uniform outer whorls bring
the nebula to a size of 5' x 3.5'. 17 s.n.


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