My recent publications in reverse chronological order

full texts are gzip-ped PostScript, abstracts are HTML

Faint and fading tails: the fate of stripped HI gas in Virgo cluster galaxies

R.Taylor, J.Köppen, P.Jáchym, R.Minchin, J.Palouš, R.Wünsch
Astron.J., (accepted 2019)
Abstract: Although many galaxies in the Virgo cluster are known to have lost significant amounts of HI gas, only about a dozen features are known where the HI extends significantly outside its parent galaxy. Previous numerical simulations have predicted that HI removed by ram pressure stripping should have column densities far in excess of the sensitivity limits of observational surveys. We construct a simple model to try and quantify how many streams we might expect to detect. This accounts for the expected random orientation of the streams in position and velocity space as well as the expected stream length and mass of stripped HI. Using archival data from the Arecibo Galaxy Environment Survey, we search for any streams which might previously have been missed in earlier analyses. We report the confident detection of ten streams as well as sixteen other less sure detections. We show that these well-match our analytic predictions for which galaxies should be actively losing gas, however the mass of the streams is typically far below the amount of missing HI in their parent galaxies, implying that a phase change and/or dispersal renders the gas undetectable. By estimating the orbital timescales we estimate that dissolution rates of 1-10 Msun/yr are able to explain both the presence of a few long, massive streams and the greater number of shorter, less massive features.

The Widefield Arecibo Virgo Extragalactic Survey I: New structures in the Kent cloud complex and an extended tail on NGC 4522

R.F.Minchin, R.Taylor, J.Köppen, J.I.Davies, W.van Driel, O.Keenan
Astron.J.158, 121 (2019)
Abstract: We are carrying out a sensitive blind survey for neutral hydrogen (HI) in the Virgo cluster and report here on the first 5° x 1° area covered, which includes two optically-dark gas features: a fivecloud HI complex (Kent et al. 2007, 2009) and the stripped tail of NGC 4522 (Kenney et al. 2004). We discover a sixth cloud and low velocity gas that extends the velocity range of the Kent complex to over 450 km/s, find that around half of the total HI ux comes from extended emission rather than compact clouds, and see around 150 percent more gas, raising the total HI mass from 5.1E8 Msun to 1.3E9 Msun. This makes the identification of NGC 4445 and NGC 4424 by Kent et al. (2009) as possible progenitors of the complex less likely, as it would require an unusually high fraction of the gas removed to have been preserved in the complex. We also identify a new component to the gas tail of NGC 4522 extending to ~200 km/s below the velocity range of the gas in the galaxy, pointing towards the eastern end of the complex. We consider the possibility that NGC 4522 may be the parent galaxy of the Kent complex, but the large velocity separation (~1800 km/s) leads us to rule this out. We conclude that, in the absence of any better candidate, NGC 4445 remains the most likely parent galaxy, although this requires it to have been particularly gas-rich prior to the event that removed its gas into the complex.

The 2-D Radiation Pattern of Parabolic Dish Antennas

DUBUS 1/19, 28 (2019)
DUBUS Technik XVII, 19 (2018)

Radio Observations of the Total Solar Eclipse on 20 March 2015

J.Köppen, with J.J.Maintoux
DUBUS 3/18, 24 (2018)

Radiation Pattern of a Parabolic Antenna Blocked by its Feed

DUBUS 1/18, 15 (2018)
DUBUS Technik XVII, 10 (2018)

Evaluating Parabolic Antennas

DUBUS 4/17, 27 (2017)
DUBUS Technik XVI, 68 (2017)
Radio Astronomy (SARA) March-April 2018, 35 (2018)

How to Measure the Atmospheric Absorption at Radio Wavelengths

DUBUS 1/16, 70 (2016)

Pointing Corrections for Large Radio Antennas

DUBUS 4/15, 74 (2015)

Efficiently Measuring Sky Positions for Pointing Corrections of Radio Telescopes

DUBUS 3/15, 17 (2015)

Ram Pressure Stripping Made Easy: An Analytical Approach

J.Köppen, P.Jáchym, R.Taylor, J.Palouš
MNRAS 479, 4367 (2018)
Abstract: The removal of gas by ram pressure stripping of galaxies is treated by a purely kinematic description. The solution has two asymptotic limits: if the duration of the ram pressure pulse exceeds the period of vertical oscillations perpendicular to the galactic plane, the commonly used quasi-static criterion of Gunn & Gott is obtained which uses the maximum ram pressure that the galaxy has experienced along its orbit. For shorter pulses the outcome depends on the time-integrated ram pressure. This parameter pair fully describes the gas mass fraction that is stripped from a given galaxy. This approach closely reproduces results from SPH simulations. We show that typical galaxies follow a very tight relation in this parameter space corresponding to a pressure pulse length of about 300 Myr. Thus, the Gunn & Gott criterion provides a good description for galaxies in larger clusters. Applying the analytic description to a sample of 232 Virgo galaxies from the GoldMine database, we show that the ICM provides indeed the ram pressures needed to explain the deficiencies. We also can distinguish current and past strippers, including objects whose stripping state was unknown.

Several interactive JavaScript tools which evaluate the analytical considerations of this paper are available at this URL

SALT reveals the barium central star of the planetary nebula Hen 2-39

B.Miszalski, H.M.Boffin, D.Jones, A.I.Karakas, J.Köppen, A.A.Tyndall, S.S.Mohamed, P.Rodrigues-Gil, M.Santander-García
MNRAS 436, 3068 (2013)

IC 4663: The first unambiguous [WN] Wolf-Rayet central star of a planetary nebula

B.Miszalski, P.A.Crowther, O.DeMarco, J.Köppen, A.F.J.Moffat, A.Acker, T.C.Hillwig
ASPC 459, 281 (2013)

BD-22°3467, a DAO-type star exciting the nebula Abell 35

M.Ziegler, T.Rauch, K.Werner, J.Köppen, J.W.Kruk
Astron.Astrophys. 548, 109 (2012)

A barium central star binary in the Type-I diamond ring planetary nebula Abell 70

B.Miszalski, H.M.J.Boffin, D.J.Frew, A.Acker, J.Köppen, A.F.J.Moffat, Q.A.Parker
MNRAS 419, 39 (2012)

PHR1315-6555: a bipolar planetary nebula in the compact Hyades-age open cluster ESO 96-SC04

Q.A.Parker,D.J.Frew, B.Miszalski, A.V.Kovacevic, P.M.Frinchaboy, P.D.Dobbie, J.Köppen
MNRAS 413, 1835 (2011)

The influence of binarity on dusty obscuration events in the planetary nebula M 2-29 and its analogues

B.Miszalski, J.Mikolajewska, J.Köppen, T.Rauch, A.Acker, M.Cohen, D.J.Frew, A.F.J.Moffat, Q.A.Parker, A.F.Jones, A.Udalski
Astron.Astrophys. 528, A39 (2011)

Mit Spritzgebäck und Silberscheibe zum eigenen Spektroskop

Sterne und Weltraum 04/2010

Starbursts in isolated galaxies: I. The influence of stellar birth function and the IMF

Ch.Theis, J.Köppen
Astron.Astrophys. 502, 486 (2009)

Ram pressure stripping of tilted galaxies

P.Jáchym, J.Köppen, J.Palouš, F.Combes
Astron.Astrophys. 500, 693 (2009)

Mit "ESA-Dresden" ins Radiouniversum

Sterne und Weltraum 03/2009

Gas stripping in galaxy clusters: a new SPH simulation approach

P.Jáchym, J.Palouš, J.Köppen, F.Combes
Astron.Astrophys. 472, 5 (2007)
Full paper in gzipped pdf-file (4.4 MB)

A possible origin of the mass-metallicity relation of galaxies

J.Köppen, C.Weidner, P.Kroupa
MNRAS 375, 120 (2007)
Full paper in pdf-file (467 kB)

Chemical compositions and plasma parameters of planetary nebulae with Wolf-Rayet type central stars

P.Girard, J.Köppen, A.Acker
Astron.Astrophys. 463, 265 (2006)
Full paper in pdf-file (412 kB)
ASCII file of fluxes and intensities (54 kB)

The Macquarie/AAO/Strasbourg H$\alpha$ Planetary Nebula Catalogue: MASH

Q.A.Parker, A.Acker, D.J.Frew, M.Hartley, A.E.J.Peyaud, S.Phillipps, D.Russeil, S.F.Beaulieu, M.Cohen, J.Köppen, J.Marcout, B.Miszalski, D.H.Morgan, R.A.H.Morris, F.Ochsenbein, M.J.Pierce, A.E.Vaughan,
MNRAS 373, 79 (2006)
Full paper in pdf-file (1.8 MB)

Effects of episodic gas infall on the chemical abundances in galaxies

J.Köppen, G.Hensler
Astron.Astrophys. 434, 531 (2005)
Full paper in pdf-file (750 kB)

PFP 1: A Large Planetary Nebula Caught in the First Stages of ISM Interaction

M.J.Pierce, D.J.Frew, Q.A.Parker, J.Köppen
Pub.Astron.Soc.Australia 21, 334 (2004)
Full paper (950 kB)

What PNe could tell about extinction inside external galaxies

Planetary Nebulae beyond the Milky Way, Proc. ESO Workshop, Garching 19-21 May 2004, eds. J.R. Walsh, L. Stanghellini, N.G. Douglas, "ESO Astrophysics Symposia". Springer, (2006), p.217
Full paper (1 kB)

Das CDROM Spectroskop

Sterne und Weltraum 11/2003

Discussion: Between simple and chemodynamical models

Galaxy Evolution - III. From simple approaches to self-consistent models, Proc. EuroConference Kiel July 16-20, 2002, eds. G.Hensler, G.Stasi\'nska, S.Harfst, P.Kroupa, Chr.Theis, Astrophys. Space Sciences, 284, 881, Kluwer, (2003)
This is the summary of one of the discussions sections of the conference. Full paper (100 kB)

A comparison of chemical and chemodynamical models

Galaxy Evolution - III. From simple approaches to self-consistent models, Proc. EuroConference Kiel July 16-20, 2002, eds. G.Hensler, G.Stasi\'nska, S.Harfst, P.Kroupa, Chr.Theis, Astrophys. Space Sciences, 284, 837, Kluwer, (2003)
Full paper (85 kB)

Evolution Chimique des Galaxies

Formation et évolution des galaxies, Ecole CNRS de Goutelas XXV, eds. A.Lançon, D.Egret, J.-L.Halbwachs, Obs.Strasbourg et SFAA, p. 129 (2003)
This is the text (in French) of lectures held in a summer school.
Full paper in ps-file (440 kB)

An inverse method to interpret colour-magnitude diagrams

J.-L.Vergely, J.Köppen, D.Egret, O.Bienaymé
Astron.Astrophys. 390, 917 (2002)
Full paper in pdf-file (3.7 MB)

PN G291.4-00.3: A new Type I planetary nebula

D.Nürnberger, S.Durand, J.Köppen, Th.Stanke, M.Sterzik, S.Els
Astron.Astrophys. 377, 241 (2001)
Full paper (800 kB)

On The Cosmic Origins Of Carbon And Nitrogen

R.B.C.Henry, M.G.Edmunds, J.Köppen
Astrophys.J. 541, 660 (2000)
Full paper (pdf) (200 kB)

Planetary Nebulae in Clusters

J.Köppen, A.Acker
Massive Stellar Clusters, Proceedings of the international workshop held in Strasbourg, France, November 8-11, 1999. Eds. A.Lançon and C.Boily.
Astronomical Society of the Pacific Conference Series., p.151 (2000)
Full paper (33 kB)

Observations of planetary nebulae in the Galactic bulge

F.Cuisinier, W.J.Maciel, A.Acker, J.Köppen, B.Stenholm
Astron.Astrophys. 353, 543 (2000)
Full paper (98 kB)

The hidden past of Sakurai's object: Stellar properties before the final helium flash

F.Kerber, J.Köppen, M.Roth, S.C.Trager
Astron.Astrophys. 344, L79 (1999)
Full paper (144 kB)

HaTr 10, a planetary nebula with extremely strong nitrogen lines

A. Tajitsu, S.Tamura, Y.Yadoumaru, R.Weinberger, J.Köppen
PASP 111, 1157 (1999)
Text of paper (30 kB)
Fig.1 (207 kB)
Fig.2 (5 kB)
Fig.3 (7 kB)
Fig.4 (4 kB)

Classification and spectral analysis of faint central stars of highly excited planetary nebulae

T.Rauch, J.Köppen, R.Napiwotzki, K.Werner
Astron.Astrophys. 347, 169 (1999)

Gas Flows and the Chemical Evolution of Galaxies: III. Graphical Analysis and Secondary Elements

J.Köppen, M.G.Edmunds
MNRAS 306, 317 (1999)
Full paper (492 kB)
There is an interactive JAVA Applet available which demonstrates the results of the paper with chemical evolution models with an arbitrary history of star formation and accretion specified by the user.

The Law of Starformation in Disk Galaxies

in The Magellanic Clouds and other dwarf galaxies, Workshop Bonn/Bochum, eds. T.Richtler, J.M.Braun, Shaker Verlag, in press (1998)
Full paper (78 kB)

The Interstellar Extinction in the Solar Neighbourhood

J.-L.Vergely, R.Freire Ferrero, D.Egret, J.Köppen
Astron.Astrophys. 340, 543 (1998)

The Opacity of the Galactic Disk derived with Planetary Nebulae

J.Köppen, J.-L.Vergely
MNRAS 299, 567 (1998)
Full paper (125 kB)

Condensation and evaporation of interstellar clouds in chemodynamical models of galaxies

J.Köppen, Ch.Theis, G.Hensler
Astron.Astrophys. 331, 524 (1998)
Full paper (232 kB)
If you like to have a more detailed description of how the system of equations was analyzed and what came out, you can get a rough manuscript here (255 kB)

The star formation law in disk galaxies - a Bayesian view

J.Köppen, H.-E.Fröhlich
Astron.Astrophys. 325, 961 (1997)
Full paper (111 kB)

The variation of abundances in planetary nebulae with height above the Galactic plane

J.Köppen, F.Cuisinier
Astron.Astrophys. 318, 98 (1996)
Full paper (132 kB)

Spectral analysis of the planetary nebula LoTr 4 and its very hot hydrogen-deficient central star

T.Rauch, J.Köppen, K.Werner
Astron.Astrophys. 310, 613 (1996)

Spectrophotometric observations of planetary nebulae high above the Galactic plane

F.Cuisinier, A.Acker, J.Köppen
Astron.Astrophys. 307, 217 (1995)

Quasar absorption lines: The chemical compositions of the absorbing clouds

O.J.Dittmann, J.Köppen
Astron.Astrophys. 297, 671 (1995)

The self-regulated star formation in chemodynamical models of galaxies

J.Köppen, C.Theis, G.Hensler
Astron.Astrophys. 296, 99 (1995)
Full paper (146 kB)

Chemical evolution in an inhomogeneous interstellar medium

M.Wilmes, J.Köppen
Astron.Astrophys. 294, 47 (1994)

Analysis of BD+33 2642 - a newly detected planetary nebula in the galactic halo and its central star

R.Napiwotzki, U.Heber, J.Köppen
Astron.Astrophys. 292, 239 (1994)

Spectral analysis of the planetary nebula K 1-27 and its very hot hydrogen-deficient central star

T.Rauch, J.Köppen, K.Werner
Astron.Astrophys. 286, 543 (1994)

Abundance gradients from disk planetary nebulae: O, Ne, S, and Ar

W.J.Maciel, J.Köppen
Astron.Astrophys. 282, 436 (1994)

The evolution of abundance gradients in spiral galaxies

Astron.Astrophys. 281, 26 (1994)

Spectrophotometric survey of southern planetary nebulae: III. Automatic model analysis

M.Samland, J.Köppen, A.Acker, B.Stenholm
Astron.Astrophys. 264, 184 (1991)

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last update: 13 Feb. 2006 J.Köppen