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Notes for object MESSIER 087

55 note(s) found in NED.


1. 2009ApJ...703.1034Y
Re:MESSIER 087
M 87. The spectra of the nucleus and jet knots are very similar, and the X-ray
flux of the knots closest to the nucleus is high. Wilson & Yang (2002) therefore
suggested that the X-ray emission of the nucleus actually comes from the jet
rather than the accretion flow. Our detailed modeling confirms their
speculation. As shown in the figure, the X-ray spectrum is well fitted by the
jet, but not by an ADAF. Di Matteo et al. (2003), on the other hand, were able
to fit the X-ray spectrum with an ADAF. This is because they do not consider the
outflow in their ADAF model.

2. 2008ApJS..177..148F
Re:3C 274
4.2.6. 3C 274 (NGC 4486, M87, Virgo A); z = 0.004360; An FR I with celebrated
optical jet. The NICMOS data were originally presented by (Corbin et al. 2002),
where the source is studied in detail.

3. 2008ApJ...687..899R
Re:MESSIER 087
M87.-The optical jet and central region, associated with the AGN, were masked
before analysis.

4. 2007MNRAS.377.1696M
Re:MESSIER 087
M87 (NGC 4486). A 2-cm VLBA measurement of the unresolved core of M87 by
Kellermann et al. (2004), with 1-mas resolution, is 3 Jy, consistent with a VLA
(1-arcsec resolution) measurement by Biretta, Stern & Harris (1991).
The UV flux is variable on short time-scales (Perlman et al. 2003; M05) as
well as on long ones (M05). At 2500 A, I will adopt a high flux of 100 * 10^-17^
erg cm^-2^ s^-1^ A^-1^, based on an HST/FOC measurement by Maoz et al. (1996). A
lower limit of the non-stellar AGN flux in the UV is obtained from the
difference between this measurement and that of M05, (100 - 55) * 10^-17^ erg
cm^-2^ s^-1^ A^-1^. At 3300 A, M05 found 48 * 10^-17^ erg cm^-2^ s^-1^ A^-1^,
and little variability between their two, closely spaced, epochs.
In X-rays, Wilson & Yang (2002) measured with Chandra a flux density at 1 keV
of 37 * 10^-14^ erg cm^-2^ s^-1^ keV^-1^. Di Matteo et al. (2003) found, using
the same data, (80 +/- 2) * 10^-14^ erg cm^-2^ s^-1^ keV^-01^. I will adopt the
mean of these two observations, 59 * 10^-14^ erg cm^-2^ s^-1^ keV^-1^. Both
analyses find a photon index of {GAMMA} = 2.2
A central BH mass of 3.4 * 10^9^ M_sun_ has been measured by Macchetto et
al. (1997) using gas kinematics.

5. 2006MNRAS.369..497K
Re:NGC 4486
The line strength in the central 3 arcsec and some part of the jet region of
this famous Virgo galaxy are clearly affected by an imperfect removal of
emission lines and non-thermal emission (Davies et al. 1993). Overall, the line
strength maps appear flat over large parts of the FoV. The H{beta} map exhibits
notably low values.

6. 2006MNRAS.366.1151S
Re:NGC 4486
The central member of the Virgo cluster, M87 displays the most complicated gas
structures in our sample. The ionized-gas distribution features several
filamentary structures and a very bright central component, consistent with
previous narrow-band observations (e.g. Sparks, Ford & Kinney 1993). In the
central 2 arcsec, the emission lines have complex profiles that are poorly
matched by single Gaussians, which explains the large central values for
{sigma}_gas_. No [O III] emission is detected along the radio jet, whereas we
have found H{beta} emission when this line is fitted independently. The gas
velocities show extreme variations across the field, particularly along the main
filamentary structures to the east of the nucleus. The ionized gas is outflowing
from the centre to the north, decelerating at larger radii. The main features of
the V_gas_ map are remarkably consistent with the long-slit observations of
Sparks et al. (1993). Most of the observed emission comes with rather
intermediate values for the [O III]/H{beta} ratio, between 1 and 2, except in
the south-eastern filament and on the closer end of the bright patch ?30 arcsec
south-east from the centre.

7. 2006ApJS..164..334F
Re:VCC 1316
VCC 1316 (M87, NGC 4486).The inner 0.25" of the g-band image is saturated. The
optical synchrotron jet emanating from the unresolved, nonthermal nucleus is
clearly visible and was masked prior to the isophotal analysis. Dust filaments
radiate from the center outward, extending out to 13" from the nucleus. There
are two very red objects close to the galaxy center: one directly south of the
nucleus, at a distance of ~6", the other southeast of the nucleus at a distance
of 11.5". The former appears to be a globular cluster, and the latter a faint
background galaxy. The isophotes appear very regular.

8. 2006ApJ...642...96E
Re:3C 274
A model fit to the spectrum consisting of a single unabsorbed power law provided
an acceptable fit to the data ({chi}^2^ = 97.8 for 100 dof). However, this fit
was significantly improved ({DELTA}{chi}^2^ = 13.6 for two additional
parameters) with the addition of a thermal component, characterized by an Apec
model of temperature 0.75^+0.17^_-0.14_ keV, abundance 0.3 of solar, and
normalization (1.11+/-0.49) x 10^-4^. Such a temperature in the inner regions of
M87 might not be unexpected, as shown from an XMM-Newton study of the radially
dependent temperatures of the hot X-ray-emitting gas in this source (Bohringer
et al. 2001). The power-law photon index for this fit is 2.09+/-0.06. For this
model, {chi}^2^ = 84.2 for 98 dof, with the probability of achieving a greater F
by chance 0.07%. No further statistically significant improvements to the fit
were achieved with more complex spectral models. We compared the results of our
Chandra nuclear spectral analysis with those found by Wilson & Yang (2002). The
power-law photon indices and normalizations are consistent, although Wilson &
Yang (2002) found evidence for slight additional absorption (N_H_ =
3.5^+1.5^_-1.4_ x 10^20^ atoms cm^-2^) at the redshift of M87.

9. 2006AJ....131.1262H
Re:MESSIER 087
1228+126 (M87): Figure 9 shows our 15 GHz VLBA image of the jet of M87 in
2003 February. No linear polarization is detected, but strong circular
polarization, m_c_ = 0.49% +- 0.10%, is seen at the peak of the core.
M87 was studied at the Very Large Array (VLA) in 2000 April by Bower
et al. (2002),who found no significant circular polarization at 8 GHz,
m_c_ = 0.01% +- 0.10%; however, they did find linear polarization at the
1.7% level. These results are the opposite of our finding of strong
circular polarization and no linear polarization. It is important to
consider that their VLA results include contributions from the jet well
beyond the region imaged by the VLBA, and that the linear polarization
they observe must come from beyond the depolarizing screen that covers
most of the VLBA-scale jet (Zavala & Taylor 2002). The fractional circular
polarization that they measure may be diluted by emission beyond the VLBA
scale, or the circular polarization may simply vary with frequency or
time. Regardless, the differing linear polarizations observed between the
VLBA- and VLA-scale images underscores our point from section 3.1 that at
least some of the lack of correlation between linear and circular
polarization for jet cores could be due to the two quantities being
produced in different regions of the unresolved jet core. M87 has been
detected intermittently in integrated circular polarization (with both
signs) at 5 GHz and below in the historical observations cataloged by
WdP83 and K84.

10. 2006A&A...460...45G
Re:NGC 4486
NGC 4486 (M 87, UGC 7654, Virgo A, Arp 152, 3C 274). Both the unresolved nuclear
emission and the jet-like feature extending ~15" to the W-NW, in the direction
of the optical jet, are seen in Fig. 5. Combined deep Chandra, ROSAT HRI and
XMM-Newton observations of this galaxy are shown in Forman et al. (2005), where
the same salient features present in our Fig. 5 can be seen with X-ray jets
clearly detected, but no spectral analysis is made. Donato et al. (2005) analyze
both Chandra and XMM-Newton data providing a radius for the core of 0.22". Dudik
et al. (2005) class it among objects exhibiting a dominant hard nuclear point
source and estimate its luminosity as L(2-10 keV) = 3.3 x 10^40^ erg s^-1^ with
a fixed {GAMMA} = 1.8 power law, in good agreement with the one we estimate (see
Table 5).

11. 2006A&A...447...97B
Re:UGC 07654
UGC 7654: this object is part of the 3C/FR I sample of low luminosity
radio-galaxies (3C 274). The Chandra data are presented in Balmaverde & Capetti
(2005).

12. 2005ApJ...635.1031B
Re:NGC 4486
NGC 4486.-This central galaxy of the Virgo Cluster (M87) has low extinction but
measurable lines of Galactic atomic and molecular gas. Unfortunately, the
Galactic C II {lambda}1036 line (1036.3 A) is coincident with the redshifted O
VI {lambda}1032 line (at 1036.4 A) and there are Galactic H_2_ lines to the red
side of the Galactic C II line, so much of a redshifted O VI {lambda}1032 line
would be absorbed (Fig. 16). Nevertheless, to the blue side of the Galactic C
II line, the continuum rises well above the expected stellar continuum (in both
the LiF1a and LiF2b spectra), suggestive of the blue side of a wide O VI
{lambda}1032 line from M87. If this is the case, the line width would needs to
be about 1.5 A (FWHM) and at least 1.2 A. If it is 1.5 A, we estimate a line
strength of 7 x 10^-15^ ergs cm^-2^ s^-1^, which is consistent with the upper
limit to the weaker O VI line of 5 x 10^-15^ ergs cm^-2^ s^-1^.
The C III {lambda}977 line is detected, with a line width of 1.4 A, although
it could be wider since the red side is absorbed by Galactic H2 lines. Ignoring
absorption by these lines, the line flux is 1.5 x 10^-14^ ergs cm^-2^ s^-1^,
stronger than the O VI line. If the H_2_ absorption produces the decrease in
the red side of the line, the line flux and line width would be about 30%
larger.

13. 2004MNRAS.352..721E
Re:NGC 4486
NGC 4486: This well-known giant elliptical galaxy has velocities
consistent with zero everywhere in the SAURON field of view, confirming
the absence of rotation, and high central velocity dispersion (Sargent
et al. 1978; Davies & Birkinshaw 1988; Bender et al. 1994; van der Marel
1994).

14. 2004ApJS..155...33S
Re:VSOP J1230+1223
(3C 274, M87) A VSOP image made from GOT data can be found in Junor
et al. (2000). The four-component model fit only accounts for the
small-scale structure. The faint core is unresolved subtending an
area of less than 0.05 mas^2^.

15. 2004A&A...424..531H
Re:3C 274
3C 274 (M 87): The SED of this FR 1 source clearly exhibits as three
basic features (1) the optical-NIR bump from the host galaxy, (2) the
thermal dust bump in the mid- and far-IR, and (3) the radio synchrotron
component. Table 1 lists the total fluxes at 450 and 850 micron,
nevertheless we were able to resolve the one-sided jet and the core in
the SCUBA jiggle maps. The core fluxes assuming a point source with FWHM
8 " and 15 "are $0.391 +- 0.10 Jy and 1.085 +- 0.10 Jy at 450 and 850
micron, respectively.

16. 2004A&A...416...41X
Re:NGC 4486
NGC 4486. This giant elliptical galaxy which is located at the center of
the Virgo cluster, hosts a very strong central radio source and a
synchrotron jet which is visible from radio to X-ray wavelengths
(Marshall et al. 2002). The nucleus of this galaxy shows no direct
signatures of dust (van Dokkum & Franx 1995) while both molecular and
atomic gas components are absent from the center of this galaxy (Braine
& Wiklind 1993). The MIR maps of this galaxy presented in Fig. A.6, show
a central emission component as well as a separate component that traces
the jet morphology. We have shown that all the MIR excess and most of
the FIR output of this galaxy as a whole (galaxy + radio jet) can be
attributed to a single synchrotron emission component as seen in Fig. 9.

17. 2003ApJS..148..419N
Re:NGC 4486
NGC 4486 (M87,- UGC 7654).-This elliptical galaxy has an irregular
nuclear dust morphology. It has a core-jet radio morphology on VLBA and
VLA scales. The STIS slits were aligned to trace morphological features
in the emission-line gas across the nuclear region of this galaxy. The
central kinematic and flux properties are listed in Table 20; the gas
exhibits a regular rotation profile. The fit to the central spectrum is
improved by the addition of a broad component. Data for this galaxy are
shown in Figure 16 (see key in Fig. 1 for an explanation of these
plots).

18. 2003ApJ...598..827P
Re:NGC 4486
NGC 4486 (M87).-NGC 4486 has the reddest UV optical colors in the UIT
sample and exhibits a very symmetric, smooth morphology in all the
images. The MUV morphology is compact (although some evidence for the
nuclear jet is evident) and centered on the nucleus, and it is
attributed to the exposed cores of evolved stars. There is also some
indication for recent star formation, possibly resulting from a cooling
flow in the cluster (McNamara & O'Connell 1989). In a study using deeper
UIT/FUV images from the Astro-2 mission, Ohl et al. (1998) conclude that
only a few percent of the FUV emission from NGC 4486 originates from an
AGN or jet and that most of the observed light is stellar in origin. No
measurable internal color dispersion between the UV and optical colors
is evident in NGC 4486.

19. 2003ApJ...589..126Z
Re:MESSIER 087
3.8. M87 The RM map for this radio galaxy was presented in Zavala &
Taylor (2002). The RMs are confined to a region from 18 to 27 mas west
of the core. The RM varied from {approx}-5000 to almost
10,000 rad m^-2^. The errors in the RMs are approximately
+- 150 rad m^-2^. A sign change in the slope of the RM is seen over a
projected distance of 0.3 pc. The electric field vectors in the area
20 mas west of the core are perpendicular to the jet boundary (Fig. 12).
The cutoff used to create the spectral index maps ({section} 3) prevents
the spectral index from being mapped in this area.

20. 2003AJ....126.2237D
Re:MESSIER 087
.
4.5. Radio Galaxies
.
M87 (F12282+1240, NGC 4486, 3C 274) is a giant elliptical galaxy at
the center of the Virgo Cluster. It has the largest radio excess in
the sample with u = -2.25. The radio source has moderate power with
L_{nu}_(4.8 GHz) = 10^24.6^ W Hz-1 and extended FR I morphology
(Martel et al. 1999). The galaxy has a bright optical synchrotron jet
and a LINER spectrum (Dopita et al. 1997). The FIR emission has low
luminosity with {nu}L_{nu}_(60 micron) = 10^8.5^L_solar_.

21. 2002ApJ...574..740T
Re:NGC 4486
NGC 4486.
The mass is the average of the values given by Harms et al. (1994)
and Macchetto et al. (1997), corrected to a distance of 16.1 Mpc.

22. 2002ApJ...567..202E
Re:VIRGO A
Virgo A is the central radio source (M87) in the Virgo cluster. Its spectrum
is a good power law, {alpha} ~ 0.8 throughout the radio range (e.g., KPTW).
To be consistent with our application here, we do not include flux above
10 GHz; thus our bolometric power is smaller than that quoted by Turland (1975),
who extrapolates to 10^15^ Hz. Recent radio images of the inner halo are in
Hines, Owen, & Eilek (1989); Owen, Eilek, & Keel (1990) presented the Faraday
image of the inner halo and used Einstein data to infer the magnetic field.
Nulsen & Bohringer (1995) present and deproject ROSAT PSPC data;
Owen et al. (2000) convert their results to H_0_ = 75 km s^-1^ Mpc, which we
use here.

23. 2002AJ....124..675C
Re:UGC 07654
Virgo A. Flux density from Condon & Broderick (1988).

24. 2001MNRAS.322..702M
Re:NGC 4486
NGC 4486 Nulsen & Bohringer (1995) find that the X-ray data for M87 are
consistent with a mass per unit length of 3.6 x 10^10^ M_sun_ kpc^-1^, or
v_c_ = 390 km s^-1^. Similarly, Tsai (1993) finds a mass
2.8 x 10^11^ M_sun_ enclosed within a radius 7.8 kpc, also giving
v_c_ = 390 km s^-1^. Using the velocity dispersion measurements of
Sembach & Tonry (1996), our models find v_c_ = (530 +/- 9) km s^-1^,
larger by 30 per cent. Part of this discrepancy is due to the fact that
Sembach & Tonry's measurements are systematically offset by 10 to
15 per cent (Sembach, private communication). Comparison with the
measurements of Sargent et al. (1978), Bender, Saglia & Gerhard (1994) and
van der Marel (1994) confirms that Sembach & Tonry's measurements are
systematically overestimated by about 15 per cent.

25. 2001ApJS..132..129M
Re:NGC 4486
NGC 4486 (M87). - This is a well-known giant E galaxy in the Virgo
cluster with an active nucleus, bright nonthermal jet, and X-ray cooling
flow. The Astro-1 UIT images are underexposed. Only the central parts of
the galaxy, including the nucleus and the nonthermal jet (the jet being
brighter), are detected (Fig. 23b). Ohl et al. (1998) analyzed deeper
exposures of M87 from Astro-2. The brightness of the nucleus and jet
notwithstanding, they find that only 10% of the FUV light within a radius
of 10" is contributed by these features and conclude that most of the UV
light of M87 is stellar.

26. 2001ApJ...552..508G
Re:3C 274
1228+12 (3C 274). - This source is well studied at all frequencies and
angular resolutions. See, e.g., Junor et al. (1999), Biretta et al. (1999),
and references therein.

27. 2001AJ....122..637H
Re:NGC 4486
NGC 4486. - Prieto (1996) attempted to determine the nuclear flux by
subtracting off a local background and fitting the "residual" nuclear
spectrum with a power law. The resulting upper limit is about twice our
value. We have used a different strategy for isolating the nuclear flux,
as described in section 4.1, and expect that our value represents a tighter
constraint on the output of the nucleus.

28. 2001AJ....121.2974L
Re:NGC 4486
NGC 4486: As the Virgo central elliptical galaxy (M87), it lies at the
center of the Virgo Cluster gravitational potential and X-ray emission,
although it is moving slightly with respect to the cluster center-of-mass
velocity as determined from galaxy velocities (Huchra 1985). Its GC system
is exceptionally rich, with over 10,000 GCs and S_N_ ~ 14 (Ashman & Zepf
1998). HST observations have allowed the bimodality to be well defined
(Elson & Santiago 1996). Spectroscopic studies have derived metallicities
and kinematics for a large number of M87 GCs (Mould, Oke, & Nemec 1987;
Huchra & Brodie 1987; Cohen, Blakeslee, & Ryzhov 1998).

29. 2000A&AS..144...53K
Re:NGC 4486
We used the photometry of Caon et al. (1990). For the effective radius
we take the value of 110 arcsec given by Peletier et al. (1990).

30. 1999MNRAS.309..969H
Re:3C 274
3.22 3C 274 (M87)
Harris, Biretta & Junor (1997) present evidence that the X-ray core
of M87 varies by ~20 per cent on time-scales of years. We use their core
count rate for 1995 June. The total counts tabulated are for the source
region they define, a 276-arcsec radius circle with background taken
from a 280-300 arcsec annulus, both centred around the X-ray core, and
our results are consistent with theirs.

31. 1999MNRAS.306..857C
Re:MESSIER 087
RX J1230.7+1220 is M87 in the Virgo cluster, and associated with the
radio source 3C 274.

32. 1999ApJS..122...81M
Re:3C 274
3C 274 (M87, NGC 4486, Virgo A). - Because of its close proximity and
spectacular optical synchrotron jet (Biretta 1993), the FR I radio
galaxy M87, located in the core of the Virgo cluster, has been the ideal
subject of a number of important astrophysical studies over the entire
electromagnetic spectrum and over a vast range of physical scales, from
its nucleus to its clustering environment. Among others, these studies
have found proper motions of the knots at apparent speeds of v ~ 0.5c
(Biretta, Zhou, & Owen 1995), a black hole of mass M ~ 2.6x10^9^ M_sun_
(Lauer et al. 1992) in the bright, compact nucleus, a disk of ionized
gas surrounding the black hole (Ford et al. 1994; Harms et al. 1994),
and an important globular cluster population (Whitmore et al. 1995).
The elliptical galaxy completely fills our WFPC2 field. The optical
jet is readily apparent at a P.A. of ~ -65^deg^, and the halo is riddled
with numerous globular clusters. The unresolved nuclear spike dominates
the nucleus. Significantly deeper HST images of M87 have been presented
in the past, such as the optical and UV FOC images of Sparks, Biretta,
& Macchetto (1994, 1996).

33. 1999AJ....118.2592V
Re:NGC 4486
M87 is the second-brightest galaxy in Virgo. The dust in M87 is
made up of irregular patches and filaments, which can be seen out to
~11" (820 pc) from the nucleus. The central emission gas was first
studied with HST by Ford et al. (1994) and Harms et al. (1994). An
isophotal fit to our central emission features agrees very well with
their results. Studies of the emission-gas kinematics yield a black hole
with a mass of ~3.2 x 10^9^ M_sun (Harms et al. 1994; Macchetto et al.
1997). Irregular spiral arms of emission extend from the disk, and
emission gas is associated with all dust features. Dopita et al. (1997)
showed that the off-nucleus emission gas has a LINER spectrum and is
excited by shocks. Carter, Johnstone, & Fabian (1997) found evidence
for many small dense clouds of gas in the core of M87 with a velocity
range of ~300 km s^-1^ using high-resolution ground-based spectroscopy.
The active nucleus in M87 emits a nonstellar continuum, which is
reported to vary in strength over time in the optical (Tsvetanov et al.
1998) and X-rays (Harris et al. 1997). The optical and radio jet have
been studied extensively (e.g., Meisenheimer, Roser, & Schlotelberg 1996
for a recent review; Biretta 1998; Perlman 1999). M87 has an apparent
one-sided optical and radio jet, but there are strong indications for a
counterjet (Sparks et al. 1992; Stiavelli et al. 1992, 1997). Our
isophotal analysis is consistent with studies by Ferrarese et al. (1994)
and Peletier et al. (1990). The latter find that the ellipticity
increases monotonically to 0.15 between 10" and ~100". This increase
enables a more robust estimate of the P.A. for this region, which
decreases from ~170^deg^ to 145^deg^.

34. 1998ApJS..114..177Z
Re:3C 274
3C 274 (M87).--This is one of the best studied radio galaxies, particularly
since it is the brightest galaxy in the Virgo Cluster, very close (individual
globular clusters can be identified even with ground based observation), and
since it exhibits a spectacular jet which is also seen in the optical. This jet
was studied already in 1956 by Baade and is seen at radio, IR, optical, UV, and
X-ray wavelengths with essentially the same morphology (Biretta, Stern, &
Harris 1991). The galaxy itself is very round, also in the central region.
Numerous high-resolution HST observations exist of this galaxy and its jet.
These are described in detail by Ford et al. (1994), Harms et al. (1994),
Thompson et al. (1995), Sparks, Biretta, & Macchetto (1996), and Capetti et al.
(1997). It also exhibits UV emission and is dominated by a nuclear component.
We include this galaxy only for completeness and do not present the UV plots.

35. 1998AJ....115.1295K
Re:MESSIER 087
1228+126.--M87 contains a well-known radio jet (e.g., Biretta & Junor 1995). Our
observations show that the inner part is well collimated with sharp edges and
has an apparent kink about 45 mas from the core.

36. 1997ApJS..112..391H
Re:NGC 4486
NGC 4486.--Although the presence of weak extensions on either side of the
[N II] lines led us to suspect, in Paper I, that broad H{alpha} might exist in
the nucleus of this famous active galaxy (M87), careful inspection of the
spectrum after starlight subtraction indicates that the [S II] lines may have
similar wings in their profiles. Note also that the nuclear spectrum obtained
with HST using a 0.26" aperture (Harms et al. 1995) show that [N II] and [S II]
have similar profiles. The enormous widths of the emission lines (FWHM~1000-1100
km s^-1^), unfortunately, cause severe blending, and so no unique model can be
determined for the highly asymmetric [S II] lines based on our data. With the
assumption that both [S II] lines have the same profile, each line can be
modeled by a combination of four Gaussian components. If we apply this model to
all three lines in the H{alpha}+[N II] blend, it can be seen that the fit is
rather poor (Fig. 12g). Adding an additional broad Gaussian to the fit will
obviously reduce the residuals, and such a component can be interpreted as
broad H{alpha} emission, but we choose not to do so because of the above
ambiguities. The small-aperture spectrum of Harms et al. also does not show
broad emission associated with H, apart from the extended wings seen in all the
narrow lines.

37. 1997AJ....114.1797W
Re:NGC 4486
NGC 4486=M87 (Whitmore et al. 1995): The case for M87 (NGC 4486), the central
elliptical galaxy in the Virgo cluster, is particularly interesting. Whitmore
et al. (1995) find a bimodal color distribution for the globular clusters in
this galaxy, with peaks near V-I=0.95 and 1.20 mag. Elson & Santiago (1996b)
find similar peaks at 0.92 and 1.23 mag. As discussed in Sec. 4.2.2, and shown
in Fig. 16, the blue peak is very similar to the old, metal-poor population of
globular clusters in the Milky Way globulars (see Elson & Santiago 1996b) while
the red peak at about V-I=1.20 is missing in Milky Way globulars. Elson &
Santiago also point out that the mean values of M_V_ for the red clusters of
M87 is roughly 0.3 mag fainter than for the blue clusters, in fair agreement
with the suggestion by Ashman et al. (1995) based on spectral evolution models
by Worthey (1994). Whitmore et al. find a similar but smaller {DELTA}V of 0.13
mag (their Table 1). Adopting the means of the Whitmore et al. (1995) and Elson
& Santiago (1996b) values (i.e., {DELTA}(V-I)=0.26 mag, {DELTA}V=0.22 mag]
leads to an estimate for the mean age of 9+/-5 Gyr. Hence a consistent picture
can be drawn which simultaneously explains the colors, luminosities, and
expected increase in metallicity of the intermediate age clusters in M87.
In addition, Whitmore et al. (1995) find that red clusters slightly outnumber
blue clusters in the central region. While Elson & Santiago (1996b) find
roughly twice as many blue clusters at 2.5' from the center of M87. This is
again consistent with the idea that younger clusters should be more
concentrated toward the center of the galaxy. Lee & Geisler (1993) also find
that the globular clusters toward the center of M87 are more metal rich, based
on Washington CCD photometry.

38. 1995ApJS...98..477H
Re:NGC 4486
(M87) The nuclear spectra of six separate exposures (taken at different
PAs) were averaged in order to increase the S/N (Fig. 66). See Paper I
for a brief discussion of this object.

39. 1994CAG1..B...0000S
Re:NGC 4486
M87
VCC 1316
Hubble Atlas, p. 2
E0
PH-422-MH
April 15/16, 1952
103aO
30 min
NGC 4486 is the second brightest galaxy in the Virgo Cluster,
after NGC 4472. It is near the center of the high-density subcluster A
(Binggeli, Tammann, and Sandage 1 987), which contains many dE dwarfs.
The galaxy was known from early times to be abnormal in its
stellar content relative to the general elliptical class. Hubble
(1926) stated that E galaxies "show no evidence of resolution" into
stars, but in a footnote he wrote "NGC 4486 (M87) may be an
exception. On the best photographs made with the 100-inch reflector,
numerous exceedingly faint images, apparently stars, are found around
the periphery." But following Hubble's (1932) identification of
globular clusters in M31 and Baade's (1944a, b) resolution of Local
Group galaxies into much fainter stars than the clusters, the objects
in M87 described by Hubble as stars were identified as globular
clusters by Baum (1955) and by Sandage (1961).
Their number in M87 is exceedingly high. The specific frequency
is a statistic defined by Harris and van den Bergh (1981) as the
number of clusters per unit M_V_ = -15 luminosity. Its value is S = 15
for NGC 4486 (Harris 1988). This number is exceeded only in NGC 1399
(panel 19) in the Fornax Cluster and in NGC 3311 in the Hydra Cluster,
and is equaled in NGC 4874 (panel 21) in the Coma Cluster.
Harris finds that the galaxies with the highest specific globular
cluster frequencies are at the centers of galaxy clusters that are
rich in nucleated dE,N dwarf ellipticals, suggesting that the globular
clusters in the giant-dominant galaxies were once nuclei of dE,N
dwarfs that have merged with the giant and decayed by dynamical
friction, an idea originally attributable to Binggeli and to
K.C. Freeman.
The print of M87 here shows the wide extent of the M87 globular
cluster system. The evidence available in 1990 (Harris 1986; 1988,
Fig. 2) is that the spatial distribution of the globular clusters in
M87 has a larger scale length than that of the halo light, suggesting
that the globular cluster system in M87 formed earlier than the
stellar halo.
M87 is also unusual in the presence of the optical jet that
starts at the unresolved (at the 0.5" level) bright nucleus.

40. 1994CAG1..B...0000S
Re:NGC 4486
M87
VCC 1316
Hubble Atlas, p. 2
E0
PH-422-MH
April 15/16, 1952
103aO
30 min
The print of NGC 4486 here is made from the same plate used for
the deeper image at the left. In this low-contrast print it is seen
that the globular cluster system has a steep density gradient toward
the center. Counts near the center are affected by incompleteness due
to the high surface brightness of the M87 envelope, making a
comparison of the radial gradient of the cluster system and of the
envelope light difficult; yet the difference between the gradient of
the cluster counts and the luminosity gradient is very large (Harris
1988).

41. 1994CAG1..B...0000S
Re:NGC 4486
M87
VCC 1316
Hubble Atlas, p. 2
E0
PH-83-S
Dec 26/27, 1951
103aO + WG2
2 min
The M87 jet, shown here to be buried in the
high-surface-brightness central regions of NGC 4486, was already known
to Curtis (1918). Note that the enlargement of this print is greater
than that of the other two prints on this page.

42. 1994A&AS..105..481M
Re:NGC 4486
NGC 4486: The isophotal analysis has been extended up to more than 8
arcmin from the center. A peculiar envelope of ever increasing
ellipticity is found (i.e. 0.5 for the last measured contour), with
pointed isophotes farther than l > 280 arcsec. Along the major-axis the
light profile is well above the r^1/4^ law.

43. 1994A&AS..105..341G
Re:NGC 4486
NGC 4486 = Virgo A
Powerful radio emitter with prominent radio and optical jet associated
with low surface-brightness radio lobes (Birkinshaw & Davies 1985). Dust
was not detected in a previous search using a colour index image
(Veron-Cetty & Veron 1988). Also the present B-I image provides no
obvious evidence for dust. However, the A_B_ image reveals some low-level
dust absorption which seems to be associated with the H{alpha}+[NII] jet
found by Jarvis (1990) (see also Sparks et al. 1993). Powerful radio and
X-ray emitter.

44. 1994A&AS..104..179G
Re:NGC 4486
NGC 4486 = Virgo A
Very round galaxy, especially in central region. Isophotes are very
elliptical, though the C3 amplitudes in the outer region seem to be
significant. The prominent optical jet was masked out in the model
fitting procedure. Residual B image reveals dust absorption coinciding
with the H{alpha}+[NII] jet found by Jarvis (1990) (see also Sparks
1993). Powerful radio and X-ray emitter.

45. 1976RC2...C...0000d
Re:NGC 4486
= M87
= Arp 152
= 3C 274
= Virgo A
Extremely bright center with jet.
Description and Structure:
P.A.S.P., 80, 129, 1968.
Ap. J. (Letters), 165, L65, 1971.
Jet Properties:
Ap. J., 151, 861, 1968.
159, 415, 1970.
A.J., 72, 796, 1967.
Astrophys. Lett., 2, 141, 1968.
Ap. & Space Sc., 14, 261, 1971.
Astrofizika, 8, 337, 1972.
Publ. A. S. Japan, 251, 175, 1973.
Ap. J. (Letters), 194, L1, 1974.
Nature, 252, 661, 1974.
Photograph:
Astrophys. Lett., 1, 1, 1967. 2, 141, 1968.
Ap. J. (Letters), 165, L65, 1971.
Ap. J. (Letters), 274, L65, 1972.
Ap. J., 159, 415, 1970.
Ap. J., 159, 195, 1971.
Astrofizika, 8, 337, 1972.
A.J., 79, 671, 1974.
Photometry:
Ap. J., 139, 284, 1964.
Astrofizika, 1, 38, 1965.
Astrophys. Lett., 2, 141, 1968.
Photometry (UBV):
Ap. J., 143, 187, 1966.
Ap. J., 172, 485, 1972.
Ap. J., 178, 25, 1972.
Ap. J., 181, 19, 1973.
Ap. J., 184, 319, 1973.
Ap. J. (Letters), 194, L1, 1974.
A.J., 7, 335, 1969.
Photometry (5 Color):
A.J., 73, 313, 1968.
Photometry (10 Color):
Ap. J., 179, 731, 1973.
Photometry (Isophotometry and Isodensitometry):
Astrophys. Lett., 4, 17, 1969.
Astrophys. Lett., 4, 23, 1969.
Ap. J., 163, 195, 1971.
A.J., 79, 671, 1974.
Photometry (I.R., 1-10 microns):
Ap. J., 143, 187, 1966.
Ap. J. (Letters), 159, L165, 1970.
Ap. J. (Letters), 176, L95, 1972.
Ap. J. (Letters), 194, L1, 1974.
A.J., 73, 866, 1968.
Photometry (Globular Clusters):
P.A.S.P., 80, 326, 1968.
P.A.S.P., 86, 311, 1974.
A.J., 73,S114, 1968.
J.R.A.S. Canada, 62, 367, 1968.
J.R.A.S. Canada, 65, 183, 1971.
Ap. J. (Letters), 152, L149, 1968.
Spectrum:
Astrophys. Lett., 1, 1, 1967.
Astrophys. Lett., 2, 65, 1968.
Ap. J., 149, 481, 1967.
Ap. J., 191, 55, 1974.
Ast.Tsirk., No. 438, 1967.
Sov. A.J., 12, 932, 1969.
Spectrum (Velocity Dispersion):
IAU Symp. No. 15, p.112, 1962.
Ap. J.Let, 156, L59, 1969.
P.A.S.P., 81, 531, 1969.
Spectrophotometry:
Observatory, 88, 239, 1968.
Ap. J., 169, 299, 1971.
Sov. A.J., 11, 777, 1968.
IAU Symp. No. 58, 169, 1974.
Polarization:
Ap. J. (Letters), 170, L53, 1971.
Ap. J. (Letters), 179, L93, 1974.
Ap. J. (Letters), 179, L97, 1974.
Dynamics and Mass Determination:
Ap. J., 139, 284, 1964.
Ap. J. (Letters), 156, L59, 1969.
P.A.S.P., 81, 531, 1969.
Mem. S.A. Ital., 41, 57, 1970.
Mem. S.A. Ital., 43, 539, 1972.

46. 1976RC2...C...0000d
Re:NGC 4486
SN1919A:
P.A.S.P., 48, 237, 1936.
HI 21cm (Intergalactic):
Astr. Ap., 3, 382, 1969.
Radio Observations:
Ap. J., 142, 106, 1965.
Ap. J., 144, 568, 1966.
Ap. J., 147, 908, 1967.
Ap. J., 148, 367, 1967.
Ap. J., 151, 43, 1968.
Ap. J., 151, 771, 1968.
Ap. J., 152, 43, 1968.
Ap. J., 154, 423, 1968.
Ap. J., 161, 1, 1970.
Ap. J., 170, 208, 1971.
Ap. J., 172, 299, 1972.
Ap. J., 193, 303, 1974.
Ap. J. (Letters), 151, L27, 1968.
Ap. J. (Letters), 159, L19, 1970.
Ap. J. (Letters), 179, L141, 1973.
Ap. J. (Letters), 180, L61, 1973.
A.J., 71, 864, 1966.
A.J., 72, 230, 1967.
A.J., 73, 1, S184, 1968.
A.J., 74, 206, 1969.
A.J., 75, 523, 1970.
A.J., 76, 537, 1971.
A.J., 77, 342, 1972.
A.J., 78, 163, 1973.
A.J., 78, 536, 1973.
A.J., 79, 139, 1974.
Astrophys. Lett., 4, 139, 1969.
Astrophys. Lett., 6, 49, 1970.
Astrophys. Lett., 8, 183, 1971.
Astr. Ap., 3, 316, 382, 1969.
M.N.R.A.S., 149, 319, 1970.
M.N.R.A.S., 152, 145, 1971.
M.N.R.A.S., 152, 439, 1971.
M.N.R.A.S., 156, 7P, 1972.
M.N.R.A.S., 166, 1P, 1974.
Mem.R.A.S., 77, Part 3, 1972.
Nature, 231, 253, 1971.
Proc. A.S. Australia, 1, 229, 1969.
Sov. A.J., 8, 1, 1964.
Sov. A.J., 9, 238, 1965.
Sov. A.J., 11, 792, 1968.
Sov. A.J., 15, 340, 1971.
Sov. A.J., 18, 42, 1974.
IAU Symp. No.44, p.222, 1972.
Radio (VLBI):
Ap. J. (Letters), 158, L83, 1969.
Ap. J., 177, 101, 1972.
Owens Valley Rad. Obs. Rep., No. 10, 1969.
X-Rays:
Science, 152, 66, 1966.
Science, 158, 257, 1967.
Ap. J. (Letters), 150, L199, 1967.
Ap. J. (Letters), 151, L131, 1968.
Ap. J. (Letters), 161, L1, 1970.
Ap. J. (Letters), 165, L49, 1971.
Ap. J. (Letters), 168, L1, 1971.
Ap. J. (Letters), 172, L41, 1972.
Ap. J. (Letters), 173, L99, 1972.
Ap. J. (Letters), 174, L65, 1972.
Ap. J. (Letters), 177, L1, 1972.
Ap. J. (Letters), 185, L13, 1973.
Ap. J. (Letters), 193, L57, 1974.
Ap. J., 179, 375, 1973.
A.J., 73, S97, 1968.
Nature, 223, 162, 1969.
Nature, 229, 544, 1971.
Nature, 230, 188, 1971.
Nature, 250, 471, 1974.
Astrophys. Lett., 10, 61, 1972.
Bull. A.A.S., 3, 236, 1971.
Bull. A.A.S., 4, 258, 1972.
Bull. A.A.S., 4, 260, 1972.
Bull. A.A.S., 5, 33, 1973.
Bull. A.A.S., 6, 429, 1974.

47. 1973UGC...C...0000N
Re:UGC 07654
Arp 152
E0-1 pec (de Vaucouleurs), E (Holmberg)
12 28.0 +12 46 = I Zw 38 = NGC 4486B (in RC1) at 7.4, 325, 0.35 x 0.35,
compact, m=14.5, E0 (de Vaucouleurs)
See UGC 07645
UGC 07658 at 7.4, 164
In Arp's class "galaxies with jets"
Virgo A radio source
Arp's short exposure shows jet
SN 1919a, possible SN 1922 (Wolf)

48. 1964RC1...C...0000d
Re:NGC 4486
= Messier 087
Extremely bright center with a blue jet. Smooth nebulosity. Many globular
clusters.
Three other E or S0 galaxies in the field.
Photograph:
Ap. J., 56, 166, 1922.
Ap. J., 114, 222, 1954.
Ap. J., 130, 342, 1959.
M.N.R.A.S., 85, 888, 1925.
P.A.S.P., 61, 123, 1949.
B.A.N., 16, 1, 1961.
Photometry:
Ap. J., 71, 231, 1930.
Ap. J., 132, 306, 1960.
Ap. J., 135, 187, 1962.
M.N.R.A.S., 94 806, 1934.
B.A.N., 16, 1, 1961.
Spectrum:
I.A.U. Symp., No. 5, 1958 = Lick Contr. II, No.81, 1958.
Ap. J., 132, 325, 1960.
Ap. J., 135, 734, 1962.
Polarization:
Ap. J., 123, 550, 1956.
Ap. J., 130, 340, 1959.
Mass:
Ap. J., 134, 910, 1961.
SN 1919
A.N., 215, 215, 1922.
P.A.S.P., 35, 261, 1923.
Ap. J., 88, 292, 1938.
Radio Emission: (Virgo A)
Nature, 164, 101, 1949.
Australian J. Phys., 6, 4, 452, 1953.
Ap. J., 119, 221, 1954.
Ap. J., 133, 322, 1961.
P.A.S.P., 72, 368, 1960.
Observatory, 76, 141, 1956.
Observatory, 81, 202, 1961.
CalTech Radio Obs., 5, 1960.

49. 1964ApJ...140...35M
Re:3C 274
No. 29.-A member of the Virgo cluster of galaxies, richness 1. Redshift from
Humason et al. (1956) .

50. 1964ApJ...139..560M
Re:MESSIER 087
e) M87
We give here the results of some measurements on M87 not included in Tables l or
2 as the technique used was not the same as for the measurements tabulated
there. As these results throw some light on the distribution of polarization
over the source, we have included them in this paper for completeness.
Previous measurements at antenna separations of 300{lambda} and greater, both
E.-W. and N.-S., have shown no detectable polarization down to the limit of 0.35
per cent (Morris and Radhakrishnan 1963; Seielstad and Wilson 1963). However,
new observations at 1420 Mc/s at an antenna separation of 150{lambda} E.-W.,
show a linear polarization of 0.6 per cent +/- 0.2 per cent in P.A. 138^deg^ +/-
7^deg^. Barat, Lequeux, and LeRoux (1960) reported a value of 3 per cent +/- 1.5
per cent at a similar frequency and resolution and suggested that the polarized
radiation arose in the "jet." On the contrary, it is now clear that the
radiation, in the halo is linearly polarized but that the central double source
(Lequeux and Heidmann 1961) remains substantially unpolarized <=0.35 per cent).
Even at 150{lambda} the halo of M87 is half resolved by an interferometer
(Lequeux 1962). The percentage of polarization that would be measured with a
single antenna that does not resolve the halo will, of course, depend entirely
on the structure of the polarization distribution and in principle is impossible
to predict from interferometer observations at a few non-zero spacings. However,
it seems unlikely that an average linear polarization of > 0.5 per cent would be
obtained. Mayer et al. (1962) have put an upper limit of1/2 per cent at 9.45 cm,
but at this frequency the contribution of the halo is negligible compared to
that of the core and the upper limit refers essentially to the latter. On the
other hand, the halo begins to predominate at wavelengths of 30 cm and longer
(Moffet 1962), and it is not inconceivable that a higher percentage of
polarization than at 20 cm mignt be found for the unresolved source. If any
depolarization effects exist in the Galaxy as suggested by Gardner and Whiteoak
(1963), the proximity of M87 to the galactic pole (b^II^ ~ 75^deg^) would
certainly help in reducing their effect at the longer wavelength.

51. 1961Hubbl.B...0000S
Re:NGC 4486
Messier 087
E0 pec
PH-422-MH
Apr. 15/16, 1952
103a0
30 min
Enlarged 7.0X
NGC 4486 (M87) is the brightest elliptical galaxy in the
Virgo Cluster. The apparent photographic magnitude is
about m(pg) = 9.7 (mean of Holmberg and Pettit-Sandage).
If (m-M) = 30.7 for the Virgo Cluster, then M(pg) = -21.0
for NGC 4486. This is one of the brightest galaxies known.
M31 has M(pg) = -20.3; NGC 0128 has M(pg) = -21.5; and a few
others are as bright. There is no question that NGC 4486
is on the bright end of the luminosity function.
NGC 4486 is peculiar in two respects. First, a very
large number (well over 500) of globular clusters are
scattered over the entire image; they show quite well in the
outer regions of the illustration. Second, a peculiar jet
starts from the nucleus and can be traced for 1500 parsecs
in the northwest direction. It is visible on the illustration
on the upper right of the facing page.
This galaxy is a source of intense radio emission. The
relation of the optical image to the radio source is
discussed by Baade and Minkowski in Ap. J., 119, 221, 1954.

52. 1961Hubbl.B...0000S
Re:NGC 4486
Messier 087
E0 pec
H-1607-H
Mar. 8/9, 1934
E40
15 min
Enlarged 15.0X
The jet in NGC 4486 is well shown in this illustration.
The orientation is the same as that of the illustration on
the left. The light of the two knots in the jet is polarized.
An illustrated discussion of the polarization is given by
Baade (Ap. J., 123, 550, 1956).

53. 1961AJ.....66..562V
Re:NGC 4486
4486 Jet. In Virgo cluster.

54. 1956AJ.....61...97H
Re:NGC 4486
HMS Note No. 137
Slit on nucleus and ray structure [north-west].
Scale of Crossley almost too small for good separation of spectra
of nucleus and ray. Also, the ray continuous spectrum is so narrow
that it is uncertain whether there are any faint absorption features
that have the same redshift as the nucleus. However, the ray spectrum
is different in not showing {lambda} 3727.
The structure and Humason's spectra of this nebula have been discussed
by Baade, W., and Minkowski, R. 1954, Ap. J., 119, 215
in connection with its identification as a radio source.

55. 1918PLicO..13....9C
Re:NGC 4486
Exceedingly bright; the sharp nucleus shows well in 5m exposure. The brighter
central portion is about 0.5' in diameter, and the total diameter about 2';
nearly round. No spiral structure is discernible. A curious straight ray
lies in a gap in the nebulosity in p.a. 20^deg^, apparently connected with the
nucleus by a thin line of matter. The ray is brightest at its inner end, which
is 11" from the nucleus. 20 s.n. .


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