Kapteyn Institute Preprints (1996)
Kapteyn Institute Preprint Service.
Preprints of the Kapteyn Institute.
Paper copies can be ordered at:
Kapteyn Institute
P.O. Box 800
9700 AV Groningen
The Netherlands
All the preprints are compressed using gzip.
1996 Preprints
-
Preprint 216
Interactions between Massive Dark Halos and Warped Disks
Konrad Kuijken
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Preprint 215
Comments on PN Evolution,
Stuart R. Pottasch
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Preprint 214
Radio Spectra of Gigahertz Peaked Spectrum Radio Sources,
W.H. de Vries, P.D. Barthel, C.P. O'Dea
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Preprint 213
The PLANET Collaboration: Probing Lensing Anomalies,
M. Albrow, J.-P. Beaulieu, P. Birch, J.A.R. Caldwell, J.
Greenhill,
K. Hill, S. Kane, R. Martin, J. Menzies, R.M. Naber, J.-W. Pel,
K. Pollard, P.D. Sackett, K.C. Sahu, P. Vreeswijk, R. Watson,
A. Williams, M. Zwaan
-
Preprint 212
Solid Methane Toward Deeply Embedded Protostars,
A.C.A. Boogert, W.A. Schutte, A.G.G.M. Tielens, D.C.B. Whittet,
F.P. Helmich, P. Ehrenfreund, P.R. Wesselius, Th. de Graauw and
T. Prusti
-
Preprint 211
Infrared Observations and Laboratory Simulations of Interstellar
CH4 and SO2,
A.C.A. Boogert, W.A. Schutte, F.P. Helmich, A.G.G.M. Tielens
and D.H. Wooden
-
Preprint 210
HI Velocity Fields and the Shapes of Dark Matter Halos,
R.H.M. Schoenmakers
-
Preprint 209
Anomalous Radio-Loudness of Cygnus A and other Powerful
Radio Galaxies,
P.D. Barthel and K.A. Arnaud
-
Preprint 208
The URSA Major Cluster of Galaxies.
I. Cluster Definition and Photometric Data,
R. Brent Tully, Marc A.W. Verheijen, Michael J. Pierce,
Jia-Sheng Huang and Richard J. Wainscoat
-
Preprint 207
K and Evolutionary Corrections from UV to IR,
B.M. Poggianti
-
Preprint 206
Beamed Radio and Far Infrared Emission in Quasars and Radio
Galaxies
H. Hoekstra, P.D. Barthel and R. Hes
-
Preprint 205
Does Low Surface Brightness Mean Low Density?
W.J.G. de Blok and S.S. McGaugh
-
Preprint 204
A Search for Counter-Rotating Stars in S0 Galaxies,
Konrad Kuijken, David Fisher and Michael R. Merrifield
-
Preprint 203
Molecular Hydrogen in the Central Regions of Southern
Infrared Galaxies,
Jan Koornneef and Frank P. Israel
-
Preprint 202
A New Chemo-Evolutionary Population Synthesis Model for Early-Type
Galaxies. I. Theoretical Basis,
A. Vazdekis, E. Casuso, R.F. Peletier, J.E. Beckman
-
Preprint 201
HI Observations of Low Surface Brightness Galaxies: Probing
Low-Density Galaxies,
W.J.G. de Blok, S.S. McGaugh and J.M. van der Hulst
-
Preprint 200
The Fundamental Plane in CL 0024+16 at z=0.4: Implications for the
Evolution of the Mass-to-Light Ratio
Pieter G. van Dokkum, and Marijn Franx
-
Preprint 199
Starbursts and the Butcher-Oemler Effect in Galaxy Clusters,
B.M. Poggianti and G. Barbaro
-
Preprint 198A
Optical Methane-band Observations of Jovian Shoemaker-Levy 9
Impact Debris,
N.G. Douglas
-
Preprint 198
Emission Line Imaging of 3CR Quasars and Radio Galaxies,
R. Hes, P.D. Barthel and R.A.E. Fosbury
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Preprint 197
Measuring the Evolution of the M/L Ratio from the Fundamental
Plane in CL 0024+16 at z=0.39,
Marijn Franx and Pieter G. van Dokkum
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Preprint 196
A Counter-Rotating Bulge in the Sb Galaxy NGC 7331,
F. Prada, M. Gutierrez, R.F. Peletier, C.D. McKeith
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Preprint 195
Scale Lengths in Disk Surface Brightness as Probes of Dust Extinction
in 3 Spiral Galaxies: M 51, NGC 3631 and M 100,
J.E. Beckman. R.F. Peletier, J.H. Knapen, R.L.M. Corradi, L.J. Gentet
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Preprint 194
Ages of Galaxy Bulges and Disks from Optical and near Infra-red
Colors,
R.F. Peletier and M. Balcells
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Preprint 193
Near-Infrared and
optical Broadband Surface Photometry
of 86 Face-on Disk Dominated Galaxies.
IV. Using color profiles to study stellar and dust content of galaxies,
Roelof S. de Jong
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Preprint 192
Neutral carbon in translucent regions of the dark cloud L183,
Ronald Stark, Paul R. Wesselius, Ewine F. van Dishoeck, R.J. Laureijs
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Preprint 191
The Ca+ Abundance of HVC Complex C,
B.P. Wakker, H. van Woerden, U.J. Schwarz, R.F. Peletier, N.G. Douglas
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Preprint 190
Near-Infrared and
optical Broadband Surface Photometry
of 86 Face-on Disk Dominated Galaxies.
III. The statistics of the disk and bulge parameters,
Roelof S. de Jong
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Preprint 189
Near-Infrared and optical Broadband Surface Photometry
of 86 Face-on Disk Dominated Galaxies.
II. A two-dimensional method to determine bulge and disk parameters,
Roelof S. de Jong
-
Preprint 188
The Fundamental Plane for Cluster E and S0 Galaxies,
Inger Jorgensen, Marijn Franx, Per Kjaergaard
Interactions between Massive Dark Halos and Warped Disks
Konrad Kuijken
Preprint No. 216
Accepted for publication in:
"Dark and Visible Matter in Galaxies and
Cosmological Implications" (eds. M. Persic & P. Salucci),
A.S.P. Conf. Series
Abstract
The normal mode theory for warping of galaxy disks, in which disks are
assumed to be tilted with respect to the equator of a massive,
flattened dark halo, assumes a rigid, fixed halo. However,
consideration of the back-reaction by a misaligned disk on a massive
particle halo shows there to be strong coupling leading to efficient
damping (or in some circumstances excitation) of the misalignment, and
hence the warp. We therefore discuss possible alternative explanations
of the warp phenomenon, with emphasis on the effect of a responsive,
gravitationally live massive galactic halo.
Comments on PN Evolution
Stuart R. Pottasch
Preprint No. 215
Accepted for publication in:
"Planetary Nebulae" (eds. H.J. Habing and H.J.G.L.M. Lamers),
Proceedings of IAU Symposium 180, Groningen, August 1996
Abstract
The improved distances given earlier in the symposium by Harris
(parallaxes) and Terzian (expansion distances) are used to discuss the
evolution of PN and their central stars. A critical note is given
concerning the use of model nebulae to derive abundances and central
star parameters.
Radio Spectra of Gigahertz Peaked Spectrum Radio Sources
W.H. de Vries, P.D. Barthel, C.P. O'Dea
Preprint No. 214
Accepted for publication in:
Astronomy and Astrophysics
Abstract
A well defined sample of 72 Gigahertz Peaked Spectrum radio sources is
compiled, having turnover frequencies in the range of 0.5 - 10 GHz.
Using this sample, the canonical GPS radio spectrum is constructed,
which is found to have a constant shape, independent of AGN type,
redshift or radio luminosity. A possible deficiency of low turnover
frequencies at high redshift is found, which may reflect a physical
mechanism where turnover frequency and radio luminosity are correlated.
The PLANET Collaboration: Probing Lensing Anomalies
M. Albrow, J.-P. Beaulieu, P. Birch, J.A.R. Caldwell, J.
Greenhill,
K. Hill, S. Kane, R. Martin, J. Menzies, R.M. Naber, J.-W. Pel,
K. Pollard, P.D. Sackett, K.C. Sahu, P. Vreeswijk, R. Watson,
A. Williams, M. Zwaan
Preprint No. 213
Accepted for publication in:
"Astrophysical Returns of Microlensing Surveys"
(eds. R. Ferlet en J.-P. Maillard),
Proceedings of the 12th Colloquium of the Institut d'Astrophysique
de Paris
Abstract
The Probing Lensing Anomalies NETwork (PLANET) is a worldwide
collaboration of astronomers using semi-dedicated European, South
African,
and Australian telescopes to perform continuous, rapid and precise
multi-band CCD photometric monitoring of
on-going Galactic microlensing events.
As well as providing important additional
information on the nature, distribution and kinematics of Galactic
microlenses, PLANET photometry is optimized for the detection of
Jovian-mass planets orbiting several AU from Galactic lenses.
The final PLANET database is expected to contain hundreds of variable
stars
sampled at hourly time scales with 1-5% precision.
Solid Methane Toward Deeply Embedded Protostars
A.C.A. Boogert, W.A. Schutte, A.G.G.M. Tielens, D.C.B. Whittet,
F.P. Helmich, P. Ehrenfreund, P.R. Wesselius, Th. de Graauw and
T. Prusti
Preprint No. 212
Accepted for publication in:
Astronomy and Astrophysics Letters
Abstract
We report on the detection of an absorption feature near 7.67 mu
toward the deeply embedded protostellar objects W 33A and
NGC 7538 : IRS9, using the ISO Short Wavelength Spectrometer.
Comparison with laboratory spectra shows that this feature can be
identified as the nu_4 (`deformation') mode of solid state CH4
embedded in polar molecules (i.e., H2O and/or CH3OH) in icy grain
mantles. The solid CH4 column density relative to solid H2O is
0.4-1.9%. Unlike solid CO, solid CH4 does not seem to be subjected to
out-gassing toward the warm source W 33A. The low gas-to-solid ratio
for CH4 argues that CH4 is formed on grains either by hydrogenation of
accreted C or by ultraviolet processing of CH3OH-rich ices.
Infrared Observations and Laboratory Simulations of Interstellar
CH4 and
SO2 of the Mass-to-Light Ratio
A.C.A. Boogert, W.A. Schutte, F.P. Helmich, A.G.G.M. Tielens
and D.H. Wooden
Preprint No. 211
Accepted for publication in:
Astronomy and Astrophysics
Abstract
Interstellar CH4 may consume a fair amount of
the carbon budget in
dense molecular clouds, but probably less than CO,
CH3OH, and CO2.
However, it can only be observed at wavelength regions in the infrared
that are heavily affected by the earth atmosphere. With new space and
airborne missions (e.g. ISO, SOFIA) in mind we have studied the near
infrared absorption spectra of solid and gaseous
CH4. We obtained
laboratory spectra of the nu4 deformation mode
(1302 cm-1, 7.68 mu)
of solid CH4 in astrophysically relevant
mixtures. We found that the
peak position and width of this absorption band vary strongly as a
function of molecular environment, compared to temperature and
particle shape effects. Hence, observations of this feature will
provide a powerful probe of the molecular composition of interstellar
ices. Also the gas phase CH4
ro-vibrational spectrum of the same band
has been calculated. Using observed physical conditions around the
protostar W 33A, we show that unresolved gaseous
CH4 lines are
detectable (at the 2-5% level) at a resolution >1000, when the column
density N>1016
cm-2.
An astrophysically relevant molecule with a very strong transition in
the same wavelength regime, is SO2.
We studied the nu3 asymmetric
stretching mode (1319 cm-1, 7.58 mu) of
solid SO2 in several
mixtures, revealing that the peak position, width and detailed profile
of this band are very sensitive to the molecular environment. Besides
probing the composition of ice mantles, observations of solid
SO2 will
provide important information on the sulfur budget locked up in grain
mantles, which is currently poorly known.
We compare the laboratory and calculated spectra of
CH4 and SO2 with
previously published ground based spectra and new airborne
observations of young stellar objects in the 7-8 mu region. W 33A,
NGC 7538 : IRS1 and IRS9 show a feature near 7.68 mu that is
consistent with absorption by solid CH4
or the Q-branch of gaseous
CH4. The column density of solid
CH4 would be 0.3-4% of solid
H2O,
indicating that solid CH4 consumes 0.5±0.3% of the cosmic carbon
abundance. A gaseous origin would imply a column density of at least
this amount, being highly dependent on the assumed temperature of the
absorbing gas. A second absorption feature is detected toward W 33A
and NGC 7538 : IRS1 at 7.58 mu. The peak position and width of this
feature are consistent with the
nu3 mode of solid
SO2 in a matrix of
solid CH3OH or pure
SO2. The derived column density is 0.1-1% of solid
H2O, indicating that solid
SO2 locks up 0.6-6% of the cosmic sulfur
abundance.
This study shows that 7-8 mu spectroscopy of dense molecular clouds,
using new airborne and space-based platforms, will provide valuable
information on the composition of icy grain mantles and molecular
cloud chemistry.
HI Velocity Fields and the Shapes of Dark Matter Halos
R.H.M. Schoenmakers
Preprint No. 210
Accepted for publication in:
"Dark and Visible Matter in Galaxies and
Cosmological Implications", eds. M. Persic and P. Salucci, A.S.P.
Conf. Series.
Abstract
I report on a new method for measuring deviations from
axisymmetry in the velocity fields of gas disks. The method
is an extension of the method that Franx, van Gorkom and
de Zeeuw developed for a single orbit gas ring.
The measurement is based upon a higher order harmonic expansion of
the full velocity field. Epicyclic theory is used to calculate the
effects of a perturbation in the potential on these harmonic
terms. It is shown how the s_1 and s_3 harmonics can be used to
measure epsilon_R sin(2 phi_{obs}), where epsilon_R is the
elongation of the potential and phi_{obs} is an (unknown) viewing
angle. The advantage of this method over
previous attempts to derive the elongation of dark matter halos is
that, by using HI, we can probe the potential at radii beyond
the stellar disk, into the regime where the dark matter is thought to
be the dominant dynamical component.
As a demonstration, I applied this method to HI velocity fields of two
spiral galaxies, NGC 2403 and NGC 3198. NGC 3198 shows a very small
epsilon_R sin(2 phi_{obs}), which suggests that the galaxy is very
nearly axisymmetric. NGC 2403 shows a larger epsilon_R
sin(2\phi_{obs}), varying in a systematic way between 0 and
0.1 and is probably influenced by spiral arms. The current data suggests
that spiral galaxies are close to axisymmetry, but a larger sample is
needed to quantify this statement.
Anomalous Radio-Loudness of Cygnus A and other Powerful
Radio Galaxies
P.D. Barthel and K.A. Arnaud
Preprint No. 209
Figure and Table are separated from the text:
- Figure
Table
Accepted for publication in: Monthly Notices of the Royal Astronomical Society (Letters).
Abstract
The nearby, extremely powerful radio galaxy Cygnus A stands out as
having an atypically low far-infrared/radio luminosity ratio. It is
demonstrated that in objects displaying such a low ratio the
radio-loudness is anomalously high, which fact is connected to these
objects inhabiting dense X-ray haloes. The enhanced radio emission is
most likely due to strong radiation losses in the dense environment.
It must be concluded that radio luminosity is not a good measure of AGN
power.
The URSA Major Cluster of Galaxies.
I. Cluster Definition and Photometric Data
R. Brent Tully, Marc A.W. Verheijen, Michael J. Pierce,
Jia-Sheng Huang and Richard J. Wainscoat
Preprint No. 208
Accepted for publication in: The Astronomical Journal.
Abstract
The Ursa Major Cluster has received remarkably little attention,
although it is as near as the Virgo Cluster and contains a comparable
number of HI-rich galaxies. In this paper, criteria for group
membership are discussed and data are presented for 79 galaxies
identified with the group. Of these, all 79 have been imaged at B,R,I
bands with CCDs, 70 have been imaged at K' with a HgCdTe array
detector, and 70 have been detected in the HI 21cm line. A complete
sample of 62 galaxies brighter than M(B)=-16.5 is identified. Images
and gradients in surface brightness and color are presented at a common
linear scale. As has been seen previously, the galaxies with the
reddest global colors are reddest at the centers and get bluer at large
radii. However, curiously, among the galaxies with the bluest global
colors there are systems with very blue cores that get redder at large
radii
K and Evolutionary Corrections from UV to IR
B.M. Poggianti
Preprint No. 207
Figures can be requested by electronic mail (bianca@astro.rug.nl).
Accepted for publication in: Astronomy and Astrophysics Supplement Series.
Abstract
K and evolutionary corrections are given for the E, Sa and Sc Hubble types
for the U, B, V, R, I, J, H, K filters
of the Johnson-Bessell & Brett photometric system and
the gri filters of the modified
Thuan & Gunn system up to the redshift z=3. Their dependence on
the time scale of star formation in ellipticals is investigated.
The corrections are computed according to an evolutionary synthesis model
that reproduces the integrated galaxy spectrum in the range
1000-25000 A; such a model makes use of an infrared observed stellar
library and its results are compared with nearby galaxies.
Evolving spectral energy distributions of
the various Hubble types, as well as optical-IR and IR-IR colour evolution
and adopted filter response functions are also given.
Beamed Radio and Far Infrared Emission in Quasars and Radio
Galaxies
H. Hoekstra, P.D. Barthel and R. Hes
Preprint No. 206
Accepted for publication in: Astronomy and Astrophysics.
Abstract
Simple orientation model predictions for the radio to far infrared
spectral energy distributions of radio-loud AGN are confronted with
observations at various radio frequencies. This model is subsequently
used to investigate 60 $\mu$m far-infrared data. The results are
supportive of the unified scheme for Fanaroff-Riley class II radio
galaxies and quasars. The relative strength of the beamed component is
derived as a function of frequency, and it is found that the higher far
infrared fluxes of quasars, as compared to radio galaxies, can be
explained invoking moderately beamed nonthermal far-infrared emission.
Does Low Surface Brightness Mean Low Density?
W.J.G. de Blok and S.S. McGaugh
Preprint No. 205
Figures are separated from the text:
- Figure 1
Figure 2
Accepted for publication in: Astrophysical Journal Letters.
Abstract
We compare the dynamical properties of two galaxies at
identical positions on the Tully-Fisher relation, but with different
surface brightnesses. We find that the low surface brightness galaxy
UGC 128 has a higher mass-to-light ratio, and yet has lower mass
densities than the high surface brightness galaxy NGC 2403. This is
true for the gas surface density, the stellar surface density, and the
total mass density.
A Search for Counter-Rotating Stars in S0 Galaxies
Konrad Kuijken, David Fisher and Michael R. Merrifield
Preprint No. 204
Figure 2 is separated from the text:
- Figure 2a
Figure 2b
Accepted for publication in Monthly Notices of the Royal
Astronomical Society.
Abstract
We have obtained high signal-to-noise spectra along the major axes of
28 S0 galaxies in order to search for the presence of disk stars on
retrograde orbits. Full line-of-sight velocity distributions were
extracted from the data, and the velocity distributions were modelled
as arising from the superposition of populations of stars on prograde
and retrograde orbits. We find no new cases in which a significant
fraction of disk stars lie on retrograde orbits; an identical analysis
of NGC~4550 does reveal the previously-known counter-rotating stellar
disk in this system. Upper limits determined for each object indicate
that no more than about 5% of the observed disk star light could arise
from counter-rotating stellar components. These results suggest that
previously-discovered disk galaxies with counter-rotating stars are
exceptional and that (at 95% confidence) at most 10% of S0 galaxies
contain significant counter-rotating populations. The most likely
value for the fraction of such S0 galaxies lies closer to 1%. This
result contrasts with the prevalence of counter-rotating gas in these
systems; combining our new observations with existing data, we find
that 24+/-8% (1-sigma error) of the gas disks in S0 galaxies
counter-rotate relative to their stellar components.
Molecular Hydrogen in the Central Regions of Southern Infrared
Galaxies
Jan Koornneef and Frank P. Israel
Preprint No. 203
To appear in: New Astronomy
Abstract
An extensive set of molecular hydrogen observations of
centers of southern infrared galaxies is presented. We
combine our data with published infrared and radio observations to
investigate the relationship between nuclear
and circumnuclear activity. We convert the observational data to
absolute luminosities, by applying the known
distances. The resulting dataset covers several decades in luminosity
for the various parameters, which observe
fairly tight correlations.
The parameters of our (power law) fits are, at the level of accuracy
achieved, not
dependent on the type of nuclear activity: while the dataset comprises a
mixture of alleged Seyfert, Liner &
Starburster galaxies, single fits match the complete sample well enough.
In particular, non-thermal nuclei
(AGN) present in some of the galaxies in the current sample, do not
stand out in the parameters we
investigated.
The absence
of a significant dependence on the nuclear type is consistent with the
idea that the
ever present starbursts energetically dominate a possible 'AGN in a
dusty environment'-component in galaxy
nuclei with infrared excesses.
The size of the H_2 emitting region is found to be proportional to the
square root of the 21 cm radio continuum
luminosity. The excitation of the circumnuclear H_2 is dominated by
shocks. If the H_2 extent marks the size of an
inner cavity in the dense molecular material surrounding a galaxy
nucleus and the radio luminosity is
proportional to the mechanical luminosity of (circum-)nuclear winds.
This result then indicates that the cavity
size occurs at constant pressure in the sample galaxies, in accordance
with the superwind model by Heckman,
Armus & Miley (1990). Our results, together with those obtained by
others, thus suggest that luminosities and
size scales of excited gas and dust around active nuclei are dominated
by the mechanical energy input. Given the
difficulties of uniquely establishing the presence of an AGN, we cannot
exclude that (a large fraction of the)
infrared luminous galaxies procure part of their radiated energy through
accretion onto a massive dark object.
A New Chemo-Evolutionary Population Synthesis Model for Early-Type
Galaxies. I. Theoretical Basis
A. Vazdekis, E. Casuso, R.F. Peletier, J.E. Beckman
Preprint No. 202
To appear in: The Astrophysical Journal Supplement
Abstract
We have developed a new stellar population synthesis model
designed to study early-type galaxies. It provides optical
and near-infrared colors, and line indices for 25 absorption lines.
It can synthesize single age, single metallicity stellar
populations or follow the galaxy through its evolution from an initial gas
cloud to the present time. The model incorporates the new isochrones
of the Padova group and the latest stellar spectral libraries.
We have applied our model to new data for a set of three early-type galaxies,
to find out whether these can
be fitted using single-age old metal-rich stellar
populations, as is normal practice when one uses other stellar models
of this kind. The model is extensively compared with previous
ones in the literature to establish its accuracy as well as the
accuracy of this kind of models in general.
Using the evolutionary version of the model we find that we cannot fit the most
metal-rich elliptical galaxies if we keep the IMF constant and
do not allow infall of gas. We do however reproduce the results
of Arimoto & Yoshii (1986) for the evolution of the gas, and
produce colors, and, for the first time with this
type of models, absorption line-strengths. It is in fact possible to fit the
data for the elliptical galaxies by varying the IMF with time.
Our numerical model is in good broad agreement with the analytical
simple model. We prefer however to calculate the evolution
of the gas numerically instead of using the simple model, since it offers
more flexibility, and even improved insight, when comparing with observations. In the present paper we describe the model, and compare a few key
observables with new data for three early-type standard galaxies.
However the data, as well as our fits, will be discussed in much more detail in
a second paper (Vazdekis et al. 1996), where some conclusions will be
drawn about elliptical galaxies on the basis of this model.
HI Observations of Low Surface Brightness Galaxies: Probing
Low-Density Galaxies
W.J.G. de Blok, S.S. McGaugh and J.M. van der Hulst
Preprint No. 201
Figure 2 is separated from the text:
- Figure
2 (1st part)
Figure
2 (2nd part)
Accepted for publication in Monthly Notices of the Royal
Astronomical Society.
Abstract
We present Very Large Array (VLA) and Westerbork Synthesis Radio
Telescope (WSRT) 21-cm HI observations of 19 late-type low
surface brightness (LSB) galaxies. Our main findings are that these
galaxies, as well as having low surface brightnesses, have low HI
surface densities, about a factor of ~3 lower than in normal
late-type galaxies. We show that LSB galaxies in some respects resemble
the outer parts of late-type normal galaxies, but may be less evolved.
LSB galaxies are more gas-rich than their high surface brightness
counterparts. The rotation curves of LSB galaxies rise more slowly than
those of HSB galaxies of the same luminosity, with amplitudes between 50
and 120 km s^{-1}, and are often still ncreasing at the outermost
measured point. The shape of the rotation curves suggests that LSB
galaxies have low matter surface densities. We use the average total
mass surface density of a galaxy as a measure for the evolutionary
state, and show that LSB galaxies are among the least compact, least
evolved galaxies. We show that both M_{HI}/L_B and M_{dyn}/L_B
depend strongly on central surface brightness, consistent with
the surface brightness-mass-to-light ratio relation required by the
Tully-Fisher relation. LSB galaxies are therefore slowly evolving
galaxies, and may well be low surface density systems in all respects.
The Fundamental Plane in CL 0024+16 at z=0.4: Implications for the
Evolution of the Mass-to-Light Ratio
Pieter G. van Dokkum, and Marijn Franx
Preprint No. 200
Figure 3 is separated from the text:
- Figure
3
Accepted for publication in Monthly Notices of the Royal
Astronomical Society.
Abstract
We present results on the Fundamental Plane of early-type galaxies in the rich
cluster CL 0024 +16 at z=0.391. The internal velocity dispersions of the
galaxies have been measured from a 19 hour integration at the MMT. The
photometric parameters of the galaxies have been measured from deep HST images.
The galaxies satisfy a tight Fundamental Plane relation which is similar to
that at low redshift. The scatter is 15% in log r_e, also very similar to
that at low redshift. The data show that massive early-type galaxies existed at
z=0.4, and extend earlier studies of the luminosities and colors of early-types
in rich clusters.
The evolution of the M/L ratio is derived from the Fundamental Plane, by a
comparison with Coma. The M/L ratio increases by 31 ± 12%
between z=0.391,
and z=0.023. The evolution is low when compared to models for stellar
populations. The expected evolution depends on the IMF, q_0, and the formation
redshift of the galaxies. The data are in agreement with high formation
redshifts. The modeling is still uncertain, however, because of various
possible biases. The most serious bias may be the progenitor bias: if the
progenitors of some current day early-types are spirals at z=0.4, they would
not be included in the sample, and the sample would be biased towards the
oldest galaxies.
More data are needed to measure the evolution of the Fundamental Plane more
precisely, and its scatter. There is a hint that the form of the Fundamental
Plane changes with redshift, and this needs to be determined better. Deeper
samples on more clusters would be valuable. Studies of the richest nearby
clusters may help to test the underlying hypothesis that the Fundamental Plane
is identical in all clusters.
Starbursts and the Butcher-Oemler Effect in Galaxy
Clusters
B.M. Poggianti and G. Barbaro
Preprint No. 199
Figures can be requested by electronic mail (bianca@astro.rug.nl).
Accepted for publication in Astronomy and Astrophysics.
Abstract
In order to explain the spectroscopic observations of most of the
galaxies in the intermediate
redshift clusters, bursts of star formation superimposed to the
traditional scenario of galactic evolution are needed.
The analysis of spectral lines and colours by means of an evolutionary
synthesis model, including both the stellar contribution and the
emission of the ionized gas, allows in most of the cases the
determination of the time elapsed since the end of the burst and the
fraction of galactic mass involved in it. In the four clusters
considered (AC103, AC114, AC118 at z = 0.31 and Cl1358+6245 at z =
0.33), the theoretical analysis demonstrates that the bursts affect
substantial galactic mass fractions, typically 30% or more.
The observations can be equally well reproduced by either
elliptical+burst
models or by spiral+burst models in which the star formation is
truncated at the end of the burst. A way to determine the galactic
original type is suggested.
Optical Methane-band Observations of Jovian Shoemaker-Levy 9
Impact Debris
N.G. Douglas
Preprint No. 198A
Figures are separated from the text:
- Figures
1-4
Accepted for publication in Astronomy and Astrophysics.
Abstract
During the encounter of comet Shoemaker-Levy 9 with Jupiter in July 1994,
narrow-band imaging was used to detect changes in methane opacity in the
upper atmosphere resulting from the impacts. Of nine debris clouds
visible in the data, seven show clear evidence of a significant change,
when compared with nearby parts of the disk, between the opacity in the
optical methane band and that in a near-lying part of the continuum.
Typical opacity
enhancement is of the order of 30%. The result is found to be
corroborated by related data from other sources. Possible reasons for
the observed effect are discussed.
Emission Line Imaging of 3CR Quasars and Radio Galaxies
R. Hes, P.D. Barthel and R.A.E. Fosbury
Preprint No. 198
Accepted for publication in Astronomy and Astrophysics.
Abstract
Optical emission line images and spectra of sixteen 3CR powerful radio
galaxies and quasars are presented. Extended line emission is detected
in both radio galaxies and quasars. We show that line luminosities,
derived from the spatially integrated [OII]lambda3727 narrow emission
line, are on average similar for radio galaxies and quasars of the same
radio power and redshift. This result supports the unified model of
these powerful radio sources, and indicates that the narrow line region
contains dust.
Measuring the Evolution of the M/L Ratio from the Fundamental
Plane in CL 0024+16 at z=0.39
Marijn Franx and Pieter G. van Dokkum
Preprint No. 197
To appear in: "New Light on Galaxy Evolution" (eds. R. Bender
and R. Davies), IAU Symposium 171, Kluwer, Dordrecht, 1996.
Abstract
The existence of the Fundamental Plane of early-type galaxies implies
that the M/L
ratios of early-types are well behaved. It provides therefore an
important tool to measure the evolution of the M/L ratio with
redshift. These measurements, in combination with measurements of the
evolution of the luminosity function, can be used to constrain the mass
evolution of galaxies.
We present the Fundamental Plane relation measured for galaxies in the
rich cluster CL 0024+16 at z=0.391. The galaxies satisfy a tight
Fundamental Plane, with relatively low scatter (15%). The M/L is
31+/-12% lower than the M/L measured in Coma, which is
consistent with simple evolutionary models. Hence, galaxies with very
similar dynamical properties existed at a z=0.4.
More, and deeper data are needed to
measure the evolution of the slope and the scatter of the
Fundamental Plane to higher accuracy. Furthermore, data on the richest
nearby clusters would be valuable to test the hypothesis that the
Fundamental Plane is independent of cluster environment.
A Counter-Rotating Bulge in the Sb Galaxy NGC 7331
F. Prada, M. Gutierrez, R.F. Peletier, C.D. McKeith
Preprint No. 196
Accepted for publication in the Astrophysical Journal Letters.
Abstract
We have found that the bulge of the large, nearby Sb galaxy NGC 7331
rotates retrograde to its disk. Analysis of spectra in the region of
the near-IR Ca II triplet along the major axis shows that, in the radial
range between 5'' and ~20'', the line of sight velocity distribution of
the absorption lines has two distinct peaks, and can be decomposed into
a fast-rotating component with v/sigma > 3, and a slower rotating,
retrograde component with v/sigma between 1-1.5. The radial surface
brightness profile of the counter-rotating component follows that of the
bulge, obtained from a 2-dimensional bulge-disk decomposition of a
near-infrared K-band image, while the fast rotating component follows
the disk. At the radius where the disk starts to dominate the isophotes
change from being considerably boxy to very disky.
Although a number of spiral galaxies have been found that contain cold,
couter-rotating disks, this is the first galaxy known to have a boxy,
probably triaxial, fairly warm, counter-rotating component, which is
dominating in the central regions. If it is a bar seen end-on, this bar
has to be thicker than the disk. We find that NGC 7331, even though it
is a fairly early-type spiral, does not have a conventional, co-rotating
bulge. The fact that the inner component is retrograde makes us believe
that it was formed from infalling material, in either stellar or gaseous
form (e.g. Balcells & Quinn 1990). Another possibility however is that
the structure has been there since the formation of the galaxy. In this
case it will be a challenge to explain the large change in orientation
of the angular momentum when going outward radially.
Scale Lengths in Disk Surface Brightness as Probes of Dust Extinction
in 3 Spiral Galaxies: M 51, NGC 3631 and M 100
J.E. Beckman. R.F. Peletier, J.H. Knapen, R.L.M. Corradi, L.J. Gentet
Preprint No. 195
Accepted for publication in the Astrophysical Journal.
Abstract
We have measured the radial brightness distributions in the disks of
three nearby face-on spirals: M 51, NGC 3631, and NGC 4321 (M 100) in
the photometric bands B through I, with the addition of the K band for M
51 only. The measurements were made by averaging azimuthally, in three
modes, the two-dimensional surface brightness over the disks in
photometric images of the objects in each band: (a) over each disk as a
whole, (b) over the spiral arms alone, and (c) over the interarm zones
alone. From these profiles scale-lengths were derived for comparison
with schematic exponential disk models incorporating interstellar dust.
These models include both absorption and scattering in their treatment
of radiative transfer. The model fits show that the arms exhibit
greater optical depth in dust than the interarm zones. The average
fraction of emitted stellar light in V which is extinguished by dust
within 3 scale-lengths of the center of each galaxy does not rise above
20% in any of them. We show that this conclusion is also valid for
models with similar overall quantities of dust, but where this is
concentrated in lanes. These can also account for the observed
scale-lengths, and their variations.
Ages of Galaxy Bulges and Disks from Optical and near Infra-red
Colors
R.F. Peletier and M. Balcells
Preprint No. 194
Accepted for publication in the Astronomical Journal.
Abstract
We compare optical and near-infrared colors of disks and bulges in a
diameter-limited sample of inclined, bright, nearby, early-type spirals.
Color profiles along wedge apertures at 15 degrees from the major axis
and on the minor axis on the side of the galaxy opposite to the dust
lane are used to assign nominal colors for the inner disks (at 2 scale
length) and for the bulges (~0.5 r_eff), respectively. We estimate
that the effects of dust reddening and the cross-talk between the colors
of the two components is negligible. We find that color differences
(bulge - disk) are very small: Delta(U-R)=0.126 +/- 0.165,
Delta(R-K)=0.078 +/- 0.165. Disks tend to be bluer by an amount three
times smaller than that reported by Bothun & Gregg (1990) for S0's.
Color variations from galaxy to galaxy are much larger than color
differences between disk and bulge in each galaxy. Probably, the
underlying old population of disks and bulges is much more similar than
the population paradigm would lead us to believe. Implied age
differences, assuming identical metallicities, are less than 30%.
Near-Infrared and optical Broadband Surface Photometry
of 86 Face-on Disk Dominated Galaxies.
IV. Using color profiles to study stellar and dust content of galaxies
Roelof S. de Jong
Preprint No. 193
Accepted for publication in Astronomy and Astrophysics.
Abstract
The stellar and dust content of spiral galaxies as function of radius
has been investigated using near-infrared and optical broadband surface
photometry of 86 face-on spiral galaxies. Colors of galaxies correlate
with the azimuthally averaged local surface brightness both within and
among galaxies, with the lower surface brightness regions being bluer.
The colors formed from different passband combinations correlate
strongly indicating that they probably arise from the same physical
process.
A 3D radiative transfer model was developed to calculate the effect of
dust absorption and scattering on the luminosity and color profiles of
galaxies. Stellar synthesis models were used to investigate the effects
of the star formation history and the metallicity on the broadband color
profiles. Combining all optical and near-infrared data shows that the
color gradients in this sample of face-on galaxies are best explained by
a combined stellar age and metallicity gradient across the disk, with
the outer regions being on average younger and of lower metallicity.
Dust reddening probably plays only a minor role, as the dust models
cannot produce reddening profiles that are compatible with the
observations.
The observed color differences implicate substantial M/L_\lambda
differences, both within galaxies and among galaxies. The variations
are such that the "missing light" problem derived from rotation
fitting becomes even worse. Late-type galaxies (T>6) have lower
metallicities and are often of younger average age than earlier types
and have therefore an entirely different M/L_\lambda in most
passbands.
The near-infrared passbands are recommended for studies where the
M/L_\lambda ratios should not vary too much.
Neutral carbon in translucent regions of the dark cloud L183
Ronald Stark, Paul R. Wesselius, Ewine F. van Dishoeck,
R.J. Laureijs
Preprint No. 192
Accepted for publication in Astronomy and Astrophysics.
Abstract
Observations of the CI ^{3}P_{1}-^{3}P_{0} 492 GHz
fine structure line and isotopic CO(2-1, 3-2) rotational lines have been
made at six positions along an east-west strip through the
centre of the high-latitude dark cloud L183 using the James Clerk Maxwell
Telescope. The CI spectra have line strengths varying between
T_{MB} = 0.8-3.4 K. The lines appear broad due to a blend of two
kinematically different components around V \simeq 1 km s^{-1} and
V \simeq 2.3 km s^{-1} which can
be resolved at some positions. If the CI emission
originates in the warmer, translucent envelopes (A_{V} \simeq 1-5 mag) of
L183 we derive total column densities in both components
in the range 7 x 10^{15}-3 x 10^{17} cm^{-2}. In case it would
come primarily from the cold dark core (A_{V} > 5 mag) we calculate lower
limits of about 10^{16}-10^{17} cm^{-2}. The component around
V \simeq 1 km s^{-1} is most likely entirely translucent.
We argue that most
of the observed CI emission from the V \simeq 2.3 km s^{-1} component also
originates in the translucent regions of L183 and has an optical
depth in the range \tau = 0.1-6. We find a good correlation between the
CI and ^{13}CO(3-2, 2-1) measurements but not with C^{18}O(2-1).
The derived C/CO column
density ratio along the cut varies between 0.08-0.7 and remains constant
within the uncertainty. Chemical model calculations are used
to study the CI column density as well as the C/CO ratio
as a function of density and total hydrogen
column density. A close inverse correlation is found
between N(C)/N(CO) and A_{V} for N(H_{2}) ~ 10^{20}- 5 x
10^{21} cm^{-2}, which is consistent with
the generally observed correlation between C and CO from
diffuse clouds to dense photon dominated regions.
The Ca+ Abundance of HVC Complex C
B.P. Wakker, H. van Woerden, U.J. Schwarz, R.F. Peletier,
N.G. Douglas
Preprint No. 191
Figures are separated from the text:
- Figure 1
- Figure 2
Accepted for publication in Astronomy and Astrophysics.
Abstract
We report the first detection of CaII H and K absorption in the high-velocity
cloud complex C, the largest HVC. Absorption is detected in the spectra of the
quasar PG 1351+640 and of the Seyfert galaxy Mark 290, at velocities of
-163 and -137 km s^{-1} (see Fig. 2). The implied Ca+ abundances are
about 2 x 10^{-8}, or about 0.01 times the total solar Calcium
abundance. This value lies near the middle of the range of values found for
other HVCs. The measured abundance will allow firm conclusions about the
distance of complex C from the presence or absence of its absorption in stellar
spectra.
Near-Infrared and optical Broadband Surface Photometry
of 86 Face-on Disk Dominated Galaxies.
III. The statistics of the disk and bulge parameters
Roelof S. de Jong
Preprint No. 190
Accepted for publication in Astronomy and Astrophysics.
Abstract
The statistics of the fundamental bulge and disk parameters of
galaxies and their relation to the Hubble sequence were investigated by
an analysis of optical and near-infrared observations of 86 face-on
spiral galaxies. The availability of near-infrared K passband data
made it possible for the first time to trace fundamental parameters
related to the luminous mass while hardly being hampered by the effects
of dust and stellar populations. The observed number frequency of
galaxies was corrected for selection effects to calculate volume number
densities of galaxies with respect to their fundamental parameters. The
main conclusions of this investigation are:
1) Freeman's law has
to be redefined. There is no single preferred value for the central
surface brightnesses of disks in galaxies. There is only an upper limit
to the central surface brightnesses of disks, while for lower central
surface brightnesses the number of galaxies per volume element
decreases only slowly as function of the central surface brightness.
2) The Hubble sequence type index correlates strongly with the
effective surface brightness of the bulge, much better than with the
bulge-to-disk ratio.
3) The disk and bulge scalelengths are
correlated.
4) These scalelengths are not correlated with Hubble
type. Hubble type is a lengthscale-free parameter and each type
therefore comes in a range of magnitudes (and presumably a range of
total masses).
5) Low surface brightness spiral galaxies are not a
separate class of galaxies. In a number of aspects they are a
continuation of a trend defined by the high surface brightness
galaxies. Low surface brightness galaxies are in general of late Hubble
type.
Near-Infrared and optical Broadband Surface Photometry
of 86 Face-on Disk Dominated Galaxies.
II. A two-dimensional method to determine bulge and disk parameters
Roelof S. de Jong
Preprint No. 189
Accepted for publication in Astronomy and Astrophysics Supplement Series.
Abstract
In this paper I present a new two-dimensional decomposition technique,
which models the surface photometry of a galaxy with an exponential
light profile for both bulge and disk and, when necessary, with a
Freeman bar. The new technique was tested for systematic errors on both
artificial and real data and compared with widely used one-dimensional
decomposition techniques, where the luminosity profile of the galaxy is
used. The comparisons indicate that a decomposition of the two-dimensional
image of the galaxy with an exponential light profile for both bulge
and disk yields the most reproducible and representative bulge and disk
parameters.
An extensive error analysis was made to determine the reliability of
the model parameters. If the model with an exponential bulge profile
is a reasonable description of a galaxy, the maximum errors in the
derived model parameters are of order 20%. The uncertainties in the
model parameters will increase, if the exponential bulge function is
replaced by other often used bulge functions as the de Vaucouleurs law.
All decomposition methods were applied to the optical and near-infrared
data set presented by de Jong & van der Kruit (1994), which
comprises 86 galaxies in six passbands.
The Fundamental Plane for Cluster E and S0 Galaxies
Inger Jorgensen, Marijn Franx, Per Kjaergaard
Preprint No. 188
Accepted for publication in Monthly Notices of the Royal Astronomical
Society.
Abstract
We have analyzed the shape of the Fundamental Plane (FP) for a
sample of 226 E and S0 galaxies in ten clusters of galaxies.
We find that the distribution of galaxies is well approximated by
a plane of the form
log r_e = 1.24 log \sigma - 0.82 log I _e + \gamma
for photometry obtained in Gunn r.
This result is in good agreement with previous determinations.
The FP has a scatter of 0.084 in log r_e.
For galaxies with velocity dispersion larger than 100 km/s the
scatter is 0.073.
If the FP is used for distance determinations this scatter is equivalent
to 17% uncertainties on distances to single galaxies.
We find that the slope of the FP is not significantly different
from cluster to cluster.
Selection effects and measurement errors can introduce biases
in the derived slope.
The residuals of the FP correlate weakly with the velocity dispersion
and the surface brightness.
Some of the coefficients used in the literature give rather
strong correlations between the residuals and absolute magnitudes.
This implies that galaxies need to be selected in a homogeneous way to
avoid biases of derived distances on the level of 5-10% or smaller.
The FP has significant intrinsic scatter.
No other structural parameters like ellipticity or
isophotal shape can reduce the scatter significantly.
This is in contradiction to simple models, which predict that the
presence of disks in E and S0 galaxies can introduce scatter in the FP.
It remains unknown what the source of scatter is.
It is therefore unknown whether this source produces systematic
errors in distance determinations.
The Mg_2-\sigma relation for the cluster galaxies differs
slightly from cluster to cluster.
Galaxies in clusters with lower velocity
dispersions have systematically lower Mg_2.
The effect can be caused by both age and metallicity variations.
With the current stellar population models,
it is in best agreement with our results regarding the FP
if the offsets are mainly caused by differences in metallicity.
Most of the distances that we derive from the FP
imply small peculiar motions (<1000 km/s). The
zero point of the FP must therefore be quite stable.
Only for one cluster, located 28 degr from the direction towards
the "Great Attractor", we find a peculiar motion of 1300 km/s.
This motion is reduced to 890 km/s if we use the FP corrected for
the offset of the Mg_2-\sigma relation.
This confirms earlier suggestions that the residuals
from the Mg_2-\sigma relation can be used to
flag galaxies with deviant populations, and possibly to
correct the distance determinations for the deviations.