Kapteyn Institute Preprints (2002)

# 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.

## 2002 Preprints

astro-ph/0212467 Discs in early-type lensing galaxies: effects on magnification ratios and measurements of $H_0$. Ole Moeller, Paul Hewett, A.W. Blain
astro-ph/0212293 Clusters of galaxies with modified Newtonian dynamics (MOND). R.H. Sanders
astro-ph/0211637 A deep search for 21cm absorption in high redshift damped Lyman-$\alpha$ systems. Nissim Kanekar, Jayaram N. Chengalur
astro-ph/0211451 Rapid Variability and Annual Cycles in the Characteristic Time-scale of the Scintillating Source PKS 1257-326. H.E. Bignall, D.L. Jauncey, J.E.J. Lovell, A.K. Tziournis, L. Kedziora-Chudczer, J.-P. Macquart, S.J. Tingay, D.P. Rayner, R.W. Clay
astro-ph/0210504 B0850+054: a new gravitational lens system from CLASS. A.D. Biggs, D. Rusin, I.W.A. Browne, A.G. de Bruyn, N.J. Jackson, L.V.E. Koopmans, J.P. McKean, S.T. Myers, R.D. Blandford, K.-H. Chae, C.D. Fassnacht, M.A. Norbury, T.J. Pearson, P.M. Phillips, A.C.S. Readhead
astro-ph/0210234 CLASS B0445+123: a new two-image gravitational lens system. M.K. Argo, N.J. Jackson, I.W.A. Browne, T. York, J.P. McKean, A.D. Biggs, R.D. Blandford, A.G. de Bruyn, K.H. Chae, C.D. Fassnacht, L.V.E. Koopmans, D.R. Marlow, S.T. Myers, M. Norbury, T.J. Pearson, P.M. Phillips, A.C.S. Readhead, D. Rusin, P.N. Wilkinson
astro-ph/0210031 Rapidly Evolving Circularly Polarized Emission during the 1994 Outburst of GRO J1665-40. J.-P. Macquart, K. Wu, R.J. Sault, D.C. Hannikainen
Preprint 337 MOND rotation curves for spiral galaxies with Cepheid-based distances. Roelof Bottema, Jose L.G. Pestana, Barry Rothberg, Robert H. Sanders
astro-ph/0207116 HST/WFPC2 proper motions in two bulge fields: kinematics and stellar population of the Galactic bulge. Konrad Kuijken, R. Michael Rich
astro-ph/0207112 Neutral Hydrogen and Optical Observations of Edge-on Galaxies: Hunting for Warps. I. Garcia-Ruiz, R. Sancisi, K. Kuijken
astro-ph/0207041 Discovery of a Group of Star-Forming Dwarf Galaxies in Abell 1367. Shoko Sakai, Robert Kennicutt, J.M. van der Hulst, Chris Moss
astro-ph/0206427 Froth across the Universe Dynamics and Stochastic Geometry of the Cosmic Foam. Rien van de Weygaert
astro-ph/0206420 High Resolution 4.7 um Keck/NIRSPEC Spectra of Protostars. II: Detection of the 13CO Isotope in Icy Grain Mantles. A.C.A. Boogert, G.A. Blake, A.G.G.M. Tielens
astro-ph/0206381 Report to Anaximander: A Dialogue on the Origin of the Cosmos in the Cradle of Western Civilization. Rien van de Weygaert
astro-ph/0206366 The Cosmic Foam: Stochastic Geometry and Spatial Clustering Across the Universe. Rien van de Weygaert
astro-ph/0205450 Automatic Observation Rendering (AMORE) I. On a synthetic stellar population's colour-magnitude diagram. Y.K. Ng, E. Brogt, C. Chiosi, G. Bertelli
astro-ph/0205254 The stellar content, metallicity and ionization structure of HII regions. N.L. Martin-Hernandez, R. Vermeij, A.G.G.M. Tielens, J.M. van der Hulst, E. Peeters
astro-ph/0205196 The Radio Properties of Composite LINER/HII Galaxies. Mercedes E. Filho, Peter D. Barthel, Luis C. Ho
astro-ph/0204521 Modified Newtonian Dynamics as an Alternative to Dark Matter. Robert H. Sanders, Stacy S. McGaugh
Preprint 336 Dark and luminous matter in the NGC 3992 group of galaxies. II. The dwarf companions UGC 6923, UGC 6940, UGC 6969, and the Tully-Fisher relation. Roelof Bottema
Preprint 335 Dark and luminous matter in the NGC 3992 group of galaxies. I. The large barred spiral NGC 3992. Roelof Bottema and Marc A.W. Verheijen
astro-ph/0204093 Microarcsecond Radio Imaging using Earth Orbit Synthesis. J.-P. Macquart, D.L. Jauncy
astro-ph/0203405 Deep H I Survey of the Spiral Galaxy NGC 2403. Filippo Fraternali, Gustaaf van Moorsel, Renzo Sancisi, Tom Oosterloo
astro-ph/0201484 Automating the Synthetic Field Method:Application to Sextans A.Benne W. Holwerda, Ronald J. Allen, Pieter C. van der Kruit
astro-ph/0201141 Detection of a Thick Disk in the edge-on Low Surface Brightness Galaxy ESO 342-G017: I. VLT Photometry in V and R Bands. Mark J. Neeser, Penny D. Sackett, Guido de Marchi, Francesco Paresce

## MOND rotation curves for spiral galaxies with Cepheid-based distances

### Roelof Bottema, Jose L.G. Pestana, Barry Rothberg, Robert H. Sanders

Preprint no. 337

Accepted for publication in Astronomy and Astrophysics.

### Abstract

Rotation curves for four spiral galaxies with recently determined Cepheid-based distances are reconsidered in terms of modified Newtonian dynamics (MOND). For two of the objects, NGC 2403 and NGC 7331, the rotation curves predicted by MOND are compatible with the observed curves when these galaxies are taken to be at the Cepheid distance. For NGC 3198, the largest distance for which reasonable agreement is obtained is 10% smaller than the Cepheid-based distance; i.e., MOND clearly prefers a smaller distance. This conclusion is unaltered when new near-infrared photometry of NGC 3198 is taken as the tracer of the stellar mass distribution. For the large Sc spiral, NGC 2841, MOND requires a distance which is at least 20% larger than the Cepheid-based distance. However, the discrepancy of the Tully-Fisher and SNIa distances with the Cepheid determination casts some doubt upon the Cepheid method in this case.

## Dark and luminous matter in the NGC 3992 group of galaxies. II. The dwarf companions UGC 6923, UGC 6940, UGC 6969, and the Tully-Fisher relation

### Roelof Bottema

Preprint no. 336

Accepted for publication in Astronomy and Astrophysics.

### Abstract

Detailed neutral hydrogen observations have been obtained of the large barred  spiral galaxy NGC 3992 and its three small companion spiral galaxies, UGC 6923, UGC 6940, and UGC 6969. Contrary to the large galaxy, for the companions the HI distribution ends quite abruptly at the optical edges. Velocity fields have been constructed from which rotation curves have been derived. Assuming a reasonable M/L ratio, a decomposition of these rotation curves generates nearly equal dark matter halos. When comparing the position-velocity diagrams of the two brightest galaxies, UGC 6923 and UGC 6969, it is obvious that the rotation curve of the latter has a shape closer to solid body than the former, yet the same maximum rotational level is reached. This is likely generated by the equal dark matter halos in combination with UGC 6923 being a factor five more luminous than UGC 6969 and so its luminous matter gives a higher contribution to the rotation in the inner regions. An NFW-CDMLambda dark halo is consistent with the observed rotation curve of UGC 6923 but not consistent with the rotation curve of UGC 6969. If the NGC 3992 group is part of the Ursa Major cluster, then the I-band M/L ratio of NGC 3992 has to be at least 1.35 times as large as that of the average spiral galaxy in the cluster. On the other hand, equal M/L ratios can be achieved when the NGC 3992 group is placed more than 3 Mpc behind the cluster. Both possibilities can explain why NGC 3992 appears to be 0.43 magnitudes too faint for its rotation..

## Dark and luminous matter in the NGC 3992 group of galaxies. I. The large barred spiral NGC 3992

### Roelof Bottema and Marc A.W. Verheijen

Preprint no. 335

Accepted for publication in Astronomy and Astrophysics.

### Abstract

Detailed neutral hydrogen observations have been obtained of the large barred spiral galaxy NGC 3992 and its three small companion galaxies, UGC 6923, UGC 6940, and UGC 6969. For the main galaxy, the HI distribution is regular with a low level radial extension outside the stellar disc. However, at exactly the region of the bar, there is a pronounced central HI hole in the gas distribution. Likely gas has been transported inwards by the bar and because of the emptyness of the hole no large accretion events can have happened in recent galactic times. The gas kinematics is very regular and it is demonstrated that the influence of the bar potential on the velocity field is negligible. A precise and extended rotation curve has been derived showing some distinct features which can be explained by the non-exponential radial light distribution of NGC 3992. The decomposition of the rotation curve gives a slight preference for a sub maximal disc, though a range of disc contributions, up to a maximum disc situation fits nearly equally well. For such a maximum disc contribution, which might be expected in order to generate and maintain the bar, the required mass-to-light ratio is large but not exceptional.

 Maintained by:  Gineke Alberts