# Welcome to galpy’s documentation¶

galpy is a Python 2 and 3 package for galactic dynamics. It supports orbit integration in a variety of potentials, evaluating and sampling various distribution functions, and the calculation of action-angle coordinates for all static potentials. galpy is an astropy affiliated package and provides full support for astropy’s Quantity framework for variables with units.

galpy is developed on GitHub. If you are looking to report an issue or for information on how to contribute to the code, please head over to galpy’s GitHub page for more information.

As a preview of the kinds of things you can do with galpy, here’s an
animation of the orbit of the Sun in galpy’s
`MWPotential2014`

potential over 7 Gyr:

## Quick-start guide¶

- Installation
- What’s new?
- Introduction
- Potentials in galpy
- Potentials and forces
- Densities
**NEW in v1.3**: Modifying potential instances using wrappers- Close-to-circular orbits and orbital frequencies
- Using interpolations of potentials
- Initializing potentials with parameters with units
**UPDATED in v1.3**: General density/potential pairs with basis-function expansions- The potential of N-body simulations
- Conversion to NEMO potentials
- Adding potentials to the galpy framework
**NEW in v1.3**: Adding wrapper potentials to the galpy framework

- Two-dimensional disk distribution functions
- Types of disk distribution functions
- Evaluating moments of the DF
- Using corrected disk distribution functions
- Oort constants and functions
- Sampling data from the DF
- Non-axisymmetric, time-dependent disk distribution functions
- Example: The Hercules stream in the Solar neighborhood as a result of the Galactic bar

- A closer look at orbit integration
- Orbit initialization
- Orbit integration
- Displaying the orbit
**NEW in v1.3**: Animating the orbit- Orbit characterization
**NEW in v1.3**Fast orbit characterization- Accessing the raw orbit
- Fast orbit integration
- Integration of the phase-space volume
- Example: The eccentricity distribution of the Milky Way’s thick disk

- Action-angle coordinates
- Action-angle coordinates for the isochrone potential
- Action-angle coordinates for spherical potentials
- Action-angle coordinates using the adiabatic approximation
- Action-angle coordinates using the Staeckel approximation
- Action-angle coordinates using an orbit-integration-based approximation
- Action-angle coordinates using the TorusMapper code
- Accessing action-angle coordinates for Orbit instances
- Example: Evidence for a Lindblad resonance in the Solar neighborhood
- Example: actions in an N-body simulation

- Three-dimensional disk distribution functions

## Tutorials¶

## Library reference¶

- Orbit (
`galpy.orbit`

) - Potential (
`galpy.potential`

) - actionAngle (
`galpy.actionAngle`

) - DF (
`galpy.df`

)- General instance routines for all df classes
- Two-dimensional, axisymmetric disk distribution functions
- Two-dimensional, non-axisymmetric disk distribution functions
- Three-dimensional disk distribution functions
- The distribution function of a tidal stream
- The distribution function of a gap in a tidal stream

- Utilities (
`galpy.util`

)

## Acknowledging galpy¶

If you use galpy in a publication, please cite the following paper

*galpy: A Python Library for Galactic Dynamics*, Jo Bovy (2015),*Astrophys. J. Supp.*,**216**, 29 (arXiv/1412.3451).

and link to `http://github.com/jobovy/galpy`

. Some of the code’s
functionality is introduced in separate papers:

`galpy.actionAngle.EccZmaxRperiRap`

and`galpy.orbit.Orbit`

methods with`analytic=True`

: Fast method for computing orbital parameters from this section: please cite Mackereth & Bovy (2018).`galpy.actionAngle.actionAngleAdiabatic`

: please cite Binney (2010).`galpy.actionAngle.actionAngleStaeckel`

: please cite Bovy & Rix (2013) and Binney (2012).`galpy.actionAngle.actionAngleIsochroneApprox`

: please cite Bovy (2014).`galpy.df.streamdf`

: please cite Bovy (2014).`galpy.df.streamgapdf`

: please cite Sanders, Bovy, & Erkal (2016).

Please also send me a reference to the paper or send a pull request including your paper in the list of galpy papers on this page (this page is at doc/source/index.rst). Thanks!

## Papers using galpy¶

`galpy`

is described in detail in this publication:

*galpy: A Python Library for Galactic Dynamics*, Jo Bovy (2015),*Astrophys. J. Supp.*,**216**, 29 (2015ApJS..216…29B).

The following is a list of publications using `galpy`

; please let me (bovy at astro dot utoronto dot ca) know if you make use of `galpy`

in a publication.

*Tracing the Hercules stream around the Galaxy*, Jo Bovy (2010),*Astrophys. J.***725**, 1676 (2010ApJ…725.1676B):Uses what later became the orbit integration routines and Dehnen and Shu disk distribution functions.

*The spatial structure of mono-abundance sub-populations of the Milky Way disk*, Jo Bovy, Hans-Walter Rix, Chao Liu, et al. (2012),*Astrophys. J.***753**, 148 (2012ApJ…753..148B):Employs galpy orbit integration in

`galpy.potential.MWPotential`

to characterize the orbits in the SEGUE G dwarf sample.

*On the local dark matter density*, Jo Bovy & Scott Tremaine (2012),*Astrophys. J.***756**, 89 (2012ApJ…756…89B):Uses

`galpy.potential`

force and density routines to characterize the difference between the vertical force and the surface density at large heights above the MW midplane.

*The Milky Way’s circular velocity curve between 4 and 14 kpc from APOGEE data*, Jo Bovy, Carlos Allende Prieto, Timothy C. Beers, et al. (2012),*Astrophys. J.***759**, 131 (2012ApJ…759..131B):Utilizes the Dehnen distribution function to inform a simple model of the velocity distribution of APOGEE stars in the Milky Way disk and to create mock data.

*A direct dynamical measurement of the Milky Way’s disk surface density profile, disk scale length, and dark matter profile at 4 kpc < R < 9 kpc*, Jo Bovy & Hans-Walter Rix (2013),*Astrophys. J.***779**, 115 (2013ApJ…779..115B):Makes use of potential models, the adiabatic and Staeckel actionAngle modules, and the quasiisothermal DF to model the dynamics of the SEGUE G dwarf sample in mono-abundance bins.

*The peculiar pulsar population of the central parsec*, Jason Dexter & Ryan M. O’Leary (2013),*Astrophys. J. Lett.*,**783**, L7 (2014ApJ…783L…7D):Uses galpy for orbit integration of pulsars kicked out of the Galactic center.

*Chemodynamics of the Milky Way. I. The first year of APOGEE data*, Friedrich Anders, Christina Chiappini, Basilio X. Santiago, et al. (2013),*Astron. & Astrophys.*,**564**, A115 (2014A&A…564A.115A):Employs galpy to perform orbit integrations in

`galpy.potential.MWPotential`

to characterize the orbits of stars in the APOGEE sample.

*Dynamical modeling of tidal streams*, Jo Bovy (2014),*Astrophys. J.*,**795**, 95 (2014ApJ…795…95B):Introduces

`galpy.df.streamdf`

and`galpy.actionAngle.actionAngleIsochroneApprox`

for modeling tidal streams using simple models formulated in action-angle space (see the tutorial above).

*The Milky Way Tomography with SDSS. V. Mapping the Dark Matter Halo*, Sarah R. Loebman, Zeljko Ivezic Thomas R. Quinn, Jo Bovy, Charlotte R. Christensen, Mario Juric, Rok Roskar, Alyson M. Brooks, & Fabio Governato (2014),*Astrophys. J.*,**794**, 151 (2014ApJ…794..151L):Uses

`galpy.potential`

functions to calculate the acceleration field of the best-fit potential in Bovy & Rix (2013) above.

*The Proper Motion of the Galactic Center Pulsar Relative to Sagittarius A**, Geoffrey C. Bower, Adam Deller, Paul Demorest, et al. (2015),*Astrophys. J.*,**798**, 120 (2015ApJ…798..120B):Utilizes

`galpy.orbit`

integration in Monte Carlo simulations of the possible origin of the pulsar PSR J1745-2900 near the black hole at the center of the Milky Way.

*The power spectrum of the Milky Way: Velocity fluctuations in the Galactic disk*, Jo Bovy, Jonathan C. Bird, Ana E. Garcia Perez, Steven M. Majewski, David L. Nidever, & Gail Zasowski (2015),*Astrophys. J.*,**800**, 83 (2015ApJ…800…83B):Uses

`galpy.df.evolveddiskdf`

to calculate the mean non-axisymmetric velocity field due to different non-axisymmetric perturbations and compares it to APOGEE data.

*The LMC geometry and outer stellar populations from early DES data*, Eduardo Balbinot, B. X. Santiago, L. Girardi, et al. (2015),*Mon. Not. Roy. Astron. Soc.*,**449**, 1129 (2015MNRAS.449.1129B):Employs

`galpy.potential.MWPotential`

as a mass model for the Milky Way to constrain the mass of the LMC.

*Generation of mock tidal streams*, Mark A. Fardal, Shuiyao Huang, & Martin D. Weinberg (2015),*Mon. Not. Roy. Astron. Soc.*,**452**, 301 (2015MNRAS.452..301F):Uses

`galpy.potential`

and`galpy.orbit`

for orbit integration in creating a*particle-spray*model for tidal streams.

*The nature and orbit of the Ophiuchus stream*, Branimir Sesar, Jo Bovy, Edouard J. Bernard, et al. (2015),*Astrophys. J.*,**809**, 59 (2015ApJ…809…59S):Uses the

`Orbit.fit`

routine in`galpy.orbit`

to fit the orbit of the Ophiuchus stream to newly obtained observational data and the routines in`galpy.df.streamdf`

to model the creation of the stream.

*Young Pulsars and the Galactic Center GeV Gamma-ray Excess*, Ryan M. O’Leary, Matthew D. Kistler, Matthew Kerr, & Jason Dexter (2015),*Phys. Rev. Lett.*, submitted (arXiv/1504.02477):Uses galpy orbit integration and

`galpy.potential.MWPotential2014`

as part of a Monte Carlo simulation of the Galactic young-pulsar population.

*Phase Wrapping of Epicyclic Perturbations in the Wobbly Galaxy*, Alexander de la Vega, Alice C. Quillen, Jeffrey L. Carlin, Sukanya Chakrabarti, & Elena D’Onghia (2015),*Mon. Not. Roy. Astron. Soc.*,**454**, 933 (2015MNRAS.454..933D):Employs galpy orbit integration,

`galpy.potential`

functions, and`galpy.potential.MWPotential2014`

to investigate epicyclic motions induced by the pericentric passage of a large dwarf galaxy and how these motions give rise to streaming motions in the vertical velocities of Milky Way disk stars.

*Chemistry of the Most Metal-poor Stars in the Bulge and the z ≳ 10 Universe*, Andrew R. Casey & Kevin C. Schlaufman (2015),*Astrophys. J.*,**809**, 110 (2015ApJ…809..110C):This paper employs galpy orbit integration in

`MWPotential`

to characterize the orbits of three very metal-poor stars in the Galactic bulge.

*The Phoenix stream: a cold stream in the Southern hemisphere*, E. Balbinot, B. Yanny, T. S. Li, et al. (2015),*Astrophys. J.*,**820**, 58 (2016ApJ…820…58B).*Discovery of a Stellar Overdensity in Eridanus-Phoenix in the Dark Energy Survey*, T. S. Li, E. Balbinot, N. Mondrik, et al. (2015),*Astrophys. J.*,**817**, 135 (2016ApJ…817..135L):Both of these papers use galpy orbit integration to integrate the orbit of NGC 1261 to investigate a possible association of this cluster with the newly discovered Phoenix stream and Eridanus-Phoenix overdensity.

*The Proper Motion of Palomar 5*, T. K. Fritz & N. Kallivayalil (2015),*Astrophys. J.*,**811**, 123 (2015ApJ…811..123F):This paper makes use of the

`galpy.df.streamdf`

model for tidal streams to constrain the Milky Way’s gravitational potential using the kinematics of the Palomar 5 cluster and stream.

*Spiral- and bar-driven peculiar velocities in Milky Way-sized galaxy simulations*, Robert J. J. Grand, Jo Bovy, Daisuke Kawata, Jason A. S. Hunt, Benoit Famaey, Arnaud Siebert, Giacomo Monari, & Mark Cropper (2015),*Mon. Not. Roy. Astron. Soc.*,**453**, 1867 (2015MNRAS.453.1867G):Uses

`galpy.df.evolveddiskdf`

to calculate the mean non-axisymmetric velocity field due to the bar in different parts of the Milky Way.

*Vertical kinematics of the thick disc at 4.5 ≲ R ≲ 9.5 kpc*, Kohei Hattori & Gerard Gilmore (2015),*Mon. Not. Roy. Astron. Soc.*,**454**, 649 (2015MNRAS.454..649H):This paper uses

`galpy.potential`

functions to set up a realistic Milky-Way potential for investigating the kinematics of stars in the thick disk.

*Local Stellar Kinematics from RAVE data - VI. Metallicity Gradients Based on the F-G Main-sequence Stars*, O. Plevne, T. Ak, S. Karaali, S. Bilir, S. Ak, Z. F. Bostanci (2015),*Pub. Astron. Soc. Aus.*,**32**, 43 (2015PASA…32…43P):This paper employs galpy orbit integration in

`MWPotential2014`

to calculate orbital parameters for a sample of RAVE F and G dwarfs to investigate the metallicity gradient in the Milky Way.

*Dynamics of stream-subhalo interactions*, Jason L. Sanders, Jo Bovy, & Denis Erkal (2015),*Mon. Not. Roy. Astron. Soc.*,**457**, 3817 (2016MNRAS.457.3817S):Uses and extends

`galpy.df.streamdf`

to build a generative model of the dynamical effect of sub-halo impacts on tidal streams. This new functionality is contained in`galpy.df.streamgapdf`

, a subclass of`galpy.df.streamdf`

, and can be used to efficiently model the effect of impacts on the present-day structure of streams in position and velocity space.

*Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way*, L. M. Howes, A. R. Casey, M. Asplund, et al. (2015),*Nature*,**527**, 484 (2015Natur.527..484H):Employs galpy orbit integration in

`MWPotential2014`

to characterize the orbits of a sample of extremely metal-poor stars found in the bulge of the Milky Way. This analysis demonstrates that the orbits of these metal-poor stars are always close to the center of the Milky Way and that these stars are therefore true bulge stars rather than halo stars passing through the bulge.

*Detecting the disruption of dark-matter halos with stellar streams*, Jo Bovy (2016),*Phys. Rev. Lett.*,**116**, 121301 (2016PhRvL.116l1301B):Uses galpy functions in

`galpy.df`

to estimate the velocity kick imparted by a disrupting dark-matter halo on a stellar stream. Also employs`galpy.orbit`

integration and`galpy.actionAngle`

functions to analyze*N*-body simulations of such an interaction.

*Identification of Globular Cluster Stars in RAVE data II: Extended tidal debris around NGC 3201*, B. Anguiano, G. M. De Silva, K. Freeman, et al. (2016),*Mon. Not. Roy. Astron. Soc.*,**457**, 2078 (2016MNRAS.457.2078A):Employs

`galpy.orbit`

integration to study the orbits of potential tidal-debris members of NGC 3201.

*Young and Millisecond Pulsar GeV Gamma-ray Fluxes from the Galactic Center and Beyond*, Ryan M. O’Leary, Matthew D. Kistler, Matthew Kerr, & Jason Dexter (2016),*Phys. Rev. D*, submitted (arXiv/1601.05797):Uses

`galpy.orbit`

integration in`MWPotential2014`

for orbit integration of pulsars kicked out of the central region of the Milky Way.

*Abundances and kinematics for ten anticentre open clusters*, T. Cantat-Gaudin, P. Donati, A. Vallenari, R. Sordo, A. Bragaglia, L. Magrini (2016),*Astron. & Astrophys.*,**588**, A120 (2016A&A…588A.120C):Uses

`galpy.orbit`

integration in`MWPotential2014`

to characterize the orbits of 10 open clusters located toward the Galactic anti-center, finding that the most distant clusters have high-eccentricity orbits.

*A Magellanic Origin of the DES Dwarfs*, P. Jethwa, D. Erkal, & V. Belokurov (2016),*Mon. Not. Roy. Astron. Soc.*,**461**, 2212 (arXiv/1603.04420):Employs the C implementations of

`galpy.potential`

s to compute forces in orbit integrations of the LMC’s satellite-galaxy population.

*PSR J1024-0719: A Millisecond Pulsar in an Unusual Long-Period Orbit*, D. L. Kaplan, T. Kupfer, D. J. Nice, et al. (2016),*Astrophys. J.*,**826**, 86 (arXiv/1604.00131):*A millisecond pulsar in an extremely wide binary system*, C. G. Bassa, G. H. Janssen, B. W. Stappers, et al. (2016),*Mon. Not. Roy. Astron. Soc.*,**460**, 2207 (arXiv/1604.00129):Both of these papers use

`galpy.orbit`

integration in`MWPotential2014`

to determine the orbit of the milli-second pulsar PSR J1024−0719, a pulsar in an unusual binary system.

*The first low-mass black hole X-ray binary identified in quiescence outside of a globular cluster*, B. E. Tetarenko, A. Bahramian, R. M. Arnason, et al. (2016),*Astrophys. J.*,**825**, 10 (arXiv/1605.00270):This paper employs

`galpy.orbit`

integration of orbits within the position-velocity uncertainty ellipse of the radio source VLA J213002.08+120904 to help characterize its nature (specifically, to rule out that it is a magnetar based on its birth location).

*Action-based Dynamical Modelling for the Milky Way Disk*, Wilma H. Trick, Jo Bovy, & Hans-Walter Rix (2016),*Astrophys. J.*,**830**, 97 (arXiv/1605.08601):Makes use of potential models, the Staeckel actionAngle modules, and the quasiisothermal DF to develop a robust dynamical modeling approach for recovering the Milky Way’s gravitational potential from kinematics of disk stars.

*A Dipole on the Sky: Predictions for Hypervelocity Stars from the Large Magellanic Cloud*, Douglas Boubert & N. W. Evans (2016),*Astrophys. J. Lett.*,**825**, L6 (arXiv/1606.02548):Uses

`galpy.orbit`

integration to investigate the orbits of hyper-velocity stars that could be ejected from the Large Magellanic Cloud and their distribution on the sky.

*Linear perturbation theory for tidal streams and the small-scale CDM power spectrum*, Jo Bovy, Denis Erkal, & Jason L. Sanders (2016),*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1606.03470):Uses and extends

`galpy.df.streamdf`

and`galpy.df.streamgapdf`

to quickly compute the effect of impacts from dark-matter subhalos on stellar streams and investigates the structure of perturbed streams and how this structure relates to the CDM subhalo mass spectrum.

*Local Stellar Kinematics from RAVE data - VII. Metallicity Gradients from Red Clump Stars*, O. Onal Tas, S. Bilir, G. M. Seabroke, S. Karaali, S. Ak, T. Ak, & Z. F. Bostanci (2016),*Pub. Astron. Soc. Aus.*,**33**, e044 (arXiv/1607.07049):Employs galpy orbit integration in

`MWPotential2014`

to calculate orbital parameters for a sample of red clump stars in RAVE to investigate the metallicity gradient in the Milky Way.

*Study of Eclipsing Binary and Multiple Systems in OB Associations IV: Cas OB6 Member DN Cas*, V. Bakis, H. Bakis, S. Bilir, Z. Eker (2016),*Pub. Astron. Soc. Aus.*,**33**, e046 (arXiv/1608.00456):Uses galpy orbit integration in

`MWPotential2014`

to calculate the orbit and orbital parameters of the spectroscopic binary DN Cas in the Milky Way.

*The shape of the inner Milky Way halo from observations of the Pal 5 and GD-1 stellar streams*, Jo Bovy, Anita Bahmanyar, Tobias K. Fritz, & Nitya Kallivayalil (2016),*Astrophys. J.*, in press (arXiv/1609.01298):Makes use of the

`galpy.df.streamdf`

model for a tidal stream to constrain the shape and mass of the Milky Way’s dark-matter halo. Introduced`galpy.potential.TriaxialNFWPotential`

.

*The Rotation-Metallicity Relation for the Galactic Disk as Measured in the Gaia DR1 TGAS and APOGEE Data*, Carlos Allende Prieto, Daisuke Kawata, & Mark Cropper (2016),*Astron. & Astrophys.*, in press (arXiv/1609.07821):Employs orbit integration in

`MWPotential2014`

to calculate the orbits of a sample of stars in common between Gaia DR1’s TGAS and APOGEE to study the rotation-metallicity relation for the Galactic disk.

*Detection of a dearth of stars with zero angular momentum in the solar neighbourhood*, Jason A. S. Hunt, Jo Bovy, & Raymond Carlberg (2016),*Astrophys. J. Lett.*,**832**, L25 (arXiv/1610.02030):Uses

`galpy.orbit`

integration in`MWPotential2014`

plus a hard Galactic core to calculate the orbits of stars in the solar neighborhood and predict how many of them should be lost to chaos.

*Differences in the rotational properties of multiple stellar populations in M 13: a faster rotation for the “extreme” chemical subpopulation*, M. J. Cordero, V. Hénault-Brunet, C. A. Pilachowski, E. Balbinot, C. I. Johnson, & A. L. Varri (2016),*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1610.09374):Employs

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbit of the globular cluster M13 and in particular whether escaping stars from the cluster could contaminate the measurement of the rotation of different populations in the cluster.

*Using the Multi-Object Adaptive Optics demonstrator RAVEN to observe metal-poor stars in and towards the Galactic Centre*, Masen Lamb, Kim Venn, David Andersen, et al. (2016),*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1611.02712):Uses

`galpy.orbit`

integration in`MWPotential2014`

to characterize the orbits of three very metal-poor stars observed toward the Galactic center, to determine whether they are likely bulge members.

*The Radial Velocity Experiment (RAVE): Fifth Data Release*, Andrea Kunder, Georges Kordopatis, Matthias Steinmetz, et al. (2016),*Astron. J.*, in press (arXiv/1609.03210):Employs

`galpy.orbit`

integration to characterize the orbits of stars in the RAVE survey.

*The Proper Motion of Pyxis: the first use of Adaptive Optics in tandem with HST on a faint halo object*, Tobias K. Fritz, Sean Linden, Paul Zivick, et al. (2016),*Astrophys. J.*, submitted (arXiv/1611.08598):Uses

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbit of the globular cluster Pyxis using its newly measured proper motion and to search for potential streams associated with the cluster.

*The Galactic distribution of X-ray binaries and its implications for compact object formation and natal kicks*, Serena Repetto, Andrei P. Igoshev, & Gijs Nelemans (2017),*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1701.01347):Uses

`galpy.orbit`

integration in`MWPotential2014`

and that of Paczynski (1990) to study the orbits of X-ray binaries under different assumptions about their formation mechanism and natal velocity kicks.

*Kinematics of Subluminous O and B Stars by Surface Helium Abundance*, P. Martin, C. S. Jeffery, Naslim N., & V. M. Woolf (2017),*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1701.03026):Uses

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbits of different types of low-mass core-helium-burning stars.

*Is there a disk of satellites around the Milky Way?*, Moupiya Maji, Qirong Zhu, Federico Marinacci, & Yuexing Li (2017), submitted (arXiv/1702.00485):Employs

`galpy.orbit`

integration in`MWPotential2014`

to predict the future paths of 11 classical Milky-Way satellites to investigate whether they remain in a disk configuration.

*The devil is in the tails: the role of globular cluster mass evolution on stream properties*, Eduardo Balbinot & Mark Gieles (2017),*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1702.02543):Uses

`galpy.orbit`

integration in`MWPotential2014`

of globular clusters in the Milky-Way halo. These integrations are used to investigate the clusters’ mass loss due to tidal stripping, taking the effects of collisional dynamics in the cluster into account, and to evaluate the visibility of their (potential) tidal tails.

*Absolute Ages and Distances of 22 GCs using Monte Carlo Main-Sequence Fitting*, Erin M. O’Malley, Christina Gilligan, & Brian Chaboyer (2017),*Astrophys. J.*, in press (arXiv/1703.01915):Employs

`galpy.orbit`

integration in`MWPotential2014`

of globular clusters in the Milky Way, to study their orbits and classify them as disk or halo clusters.

- Siriusly,
*a newly identified intermediate-age Milky Way stellar cluster: A spectroscopic study of*Gaia*1*, J. D. Simpson, G. M. De Silva, S. L. Martell, D. B. Zucker, A. M. N. Ferguson, E. J. Bernard, M. Irwin, J. Penarrubia, & E. Tolstoy (2017),*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1703.03823): Uses

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbit in the Milky Way potential of a newly-confirmed stellar cluster found in the Gaia data.

- Siriusly,
*Action-based Dynamical Modeling for the Milky Way Disk: The Influence of Spiral Arms*, Wilma H. Trick, Jo Bovy, Elena D’Onghia, & Hans-Walter Rix (2017),*Astrophys. J., in press*(arXiv/1703.05970):Uses various potential models, the Staeckel actionAngle modules, and the quasiisothermal DF to test a robust dynamical modeling approach for recovering the Milky Way’s gravitational potential from kinematics of disk stars against numerical simulations with spiral arms.

*A spectroscopic study of the elusive globular cluster ESO452-SC11 and its surroundings*, Andreas Koch, Camilla Juul Hansen, & Andrea Kunder (2017),*Astron. & Astrophys.*, submitted (arXiv/1703.06921):Employs

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbit in the Milky Way potential of two candidate cluster members of the bulge globular cluster ESO452-SC11.

*A Halo Substructure in Gaia Data Release 1*, G. C. Myeong, N. W. Evans, V. Belokurov, S. E. Koposov, & J. L. Sanders (2017),*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1704.01363):Uses

`galpy.actionAngle.actionAngleAdiabatic`

routines to compute the actions using the adiabatic approximation for 268,588 stars in*Gaia*DR1*TGAS*with line-of-sight velocities from spectroscopic surveys. Detects a co-moving group of 14 stars on strongly radial orbits and computes their orbits using`MWPotential2014`

.

*An artificial neural network to discover Hypervelocity stars: Candidates in*Gaia*DR1/*TGAS, T. Marchetti, E. M. Rossi, G. Kordopatis, A. G. A. Brown, A. Rimoldi, E. Starkenburg, K. Youakim, & R. Ashley (2017),*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1704.07990):Uses

`galpy.orbit`

integration in a custom Milky-Way-like potential built from`galpy.potential`

models to investigate the orbits of hypervelocity-star candidates in*Gaia*DR1.

*GalRotpy: an educational tool to understand and parametrize the rotation curve and gravitational potential of disk-like galaxies*, Andrés Granados, Lady-J. Henao-O., Santiago Vanegas, & Leonardo Castañeda (2017; arXiv/1705.01665):These authors build an interactive tool to decompose observed rotation curves into bulge, disk (Miyamoto-Nagai or exponential), and NFW halo components on top of

`galpy.potential`

routines.

*The AMBRE Project: formation and evolution of the Milky Way disc*, V. Grisoni, E. Spitoni, F. Matteucci, A. Recio-Blanco, P. de Laverny, M. Hayden, S. Mikolaitis, & C. C. Worley (2017)*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1706.02614):Uses

`galpy`

to compute orbital parameters for stars in the AMBRE sample of high-resolution spectra and uses these orbital parameters to aid in the comparison between the data and chemical-evolution models.

*Low-mass X-ray binaries from black-hole retaining globular clusters*, Matthew Giesler, Drew Clausen, & Christian D. Ott (2017)*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1708.05915):Employs

`galpy.orbit`

integration in`MWPotential2014`

to compute the orbits of MW globular clusters and simulated ejected BH low-mass X-ray binaries from these globular clusters to determine where they end up today.

*ESO452-SC11: The lowest mass globular cluster with a potential chemical inhomogeneity*, Jeffrey D. Simpson, Gayandhi De Silva, Sarah L. Martell, Colin A. Navin, & Daniel B. Zucker (2017)*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1708.06875):Uses

`galpy.orbit`

in`MWPotential2014`

to compute the orbit of the MW bulge globular cluster ESO452-SC11.

*The Hercules stream as seen by APOGEE-2 South*, Jason A. S. Hunt, Jo Bovy, Angeles Pérez-Villegas, et al. (2017)*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1709.02807):Uses

`galpy.df.evolveddiskdf`

to compute the effect of a fast-rotating Milky-Way bar model on the velocity distribution in the disk of the Milky Way near the Sun to compare to the observed line-of-sight velocity distribution in APOGEE-2 South.

*Detailed chemical abundance analysis of the thick disk star cluster Gaia 1*, Andreas Koch, Terese T. Hansen, & Andrea Kunder (2017)*Astron. & Astrophys.*, in press (arXiv/1709.04022):Employs

`galpy.orbit`

integration to compute the orbits of four red-giant members of the*Gaia 1*Milky Way star cluster, finding that the orbits of these stars are similar to those of the oldest stars in the Milky Way’s disk.

*Proper motions in the VVV Survey: Results for more than 15 million stars across NGC 6544*, R. Contreras Ramos, M. Zoccali, F. Rojas, A. Rojas-Arriagada, M. Gárate, P. Huijse, F. Gran, M. Soto, A.A.R. Valcarce, P. A. Estévez, & D. Minniti (2017)*Astron. & Astrophys.*, in press (arXiv/1709.07919):Uses

`galpy.orbit`

integration in`MWPotential2014`

to calculate the orbit of NGC 6544, a Milky-Way globular cluster, using a newly determined proper motion, finding that it is likely a halo globular cluster based on its orbit.

*How to make a mature accreting magnetar*, A. P. Igoshev & S. B. Popov (2017)*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1709.10385):Employs

`galpy.orbit`

integration of the magnetar candidate 4U 0114+65 in the potential model from Irrgang et al. (2013) to aid in the determination of its likely age.

*iota Horologii is unlikely to be an evaporated Hyades star*, I. Ramirez, D. Yong, E. Gutierrez, M. Endl, D. L. Lambert, J.-D. Do Nascimento Jr (2017)*Astrophys. J.*, in press (arXiv/1710.05930):Uses

`galpy.orbit`

integration in`MWPotential2014`

to determine the approximate orbit of the star iota Horologii, a planet-hosting suspected former member of the Hyades cluster, to investigate whether it could have coincided with the Hyades cluster in the past.

*Confirming chemical clocks: asteroseismic age dissection of the Milky Way disk(s)*, V. Silva Aguirre, M. Bojsen-Hansen, D. Slumstrup, et al. (2017)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1710.09847):Employs

`galpy.orbit`

integration in`MWPotential2014`

to compute the orbits of a sample of 1989 red giants with spectroscopic and asteroseismic data from the APOKASC catalog, to shed light on the properties of stellar populations defined by age and metallicity.

*The universality of the rapid neutron-capture process revealed by a possible disrupted dwarf galaxy star*, Andrew R. Casey & Kevin C. Schlaufman (2017)*Astrophys. J.*, in press (arXiv/1711.04776):Uses

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbit and its uncertainty of 2MASS J151113.24–213003.0, an extremely metal-poor field star with measureable r-process abundances, and of other similar metal-poor stars. The authors find that all of these stars are on highly eccentric orbits, possibly indicating that they originated in dwarf galaxies.

*The Gaia-ESO Survey: Churning through the Milky Way*, M. R. Hayden, A. Recio-Blanco, P. de Laverny, et al. (2017)*Astron. & Astrophys.*, in press (arXiv/1711.05751):Employs

`galpy.orbit`

integration in`MWPotential2014`

to study the orbital characteristics (eccentricity, pericentric radius) of a sample of 2,364 stars observed in the Milky Way as part of the Gaia-ESO survey.

*The Evolution of the Galactic Thick Disk with the LAMOST Survey*, Chengdong Li & Gang Zhao (2017)*Astrophys. J.*,**850**, 25 (2017ApJ…850…25L):Uses

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbital characteristics (eccentricity, maximum height above the plane, angular momentum) of a sample of about 2,000 stars in the thicker-disk component of the Milky Way.

*The Orbit and Origin of the Ultra-faint Dwarf Galaxy Segue 1*, T. K. Fritz, M. Lokken, N. Kallivayalil, A. Wetzel, S. T. Linden, P. Zivick, & E. J. Tollerud (2017)*Astrophys. J.*, submitted (arXiv/1711.09097):Employs

`galpy.orbit`

integration in`MWPotential2014`

and a version of this potential with a more massive dark-matter halo to investigate the orbit and origin of the dwarf-spheroidal galaxy Segue 1 using a newly measured proper motion with SDSS and LBC data.

*Prospects for detection of hypervelocity stars with Gaia*, T. Marchetti, O. Contigiani, E. M. Rossi, J. G. Albert, A. G. A. Brown, & A. Sesana (2017)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1711.11397):Uses

`galpy.orbit`

integration in a custom Milky-Way-like potential built from`galpy.potential`

models to create mock catalogs of hypervelocity stars in the Milky Way for different ejection mechanisms and study the prospects of their detection with*Gaia*.

*The AMBRE project: The thick thin disk and thin thick disk of the Milky Way*, Hayden, M. R., Recio-Blanco, A., de Laverny, P., Mikolaitis, S., & Worley, C. C. (2017)*Astron. & Astrophys.*,**608**, L1 (arXiv/1712.02358):Employs

`galpy.orbit`

integration in`MWPotential2014`

to characterize the orbits of 494 nearby stars analyzed as part of the AMBRE project to learn about their distribution within the Milky Way.

*KELT-21b: A Hot Jupiter Transiting the Rapidly-Rotating Metal-Poor Late-A Primary of a Likely Hierarchical Triple System*, Marshall C. Johnson, Joseph E. Rodriguez, George Zhou, et al. (2017)*Astrophys. J.*, submitted (arXiv/1712.03241):Uses

`galpy.orbit`

integration in`MWPotential2014`

to investigate the Galactic orbit of KELT-21b, a hot jupiter around a low-metallicity A-type star.

*GalDynPsr: A package to estimate dynamical contributions in the rate of change of the period of radio pulsars*, Dhruv Pathak & Manjari Bagchi (2017) (arXiv/1712.06590):Presents a python package to compute contributions to the GR spin-down of pulsars from the differential galactic acceleration between the Sun and the pulsar. The package uses

`MWPotential2014`

and`galpy.potential`

functions to help compute this.

*Local Stellar Kinematics from RAVE data – VIII. Effects of the Galactic Disc Perturbations on Stellar Orbits of Red Clump Stars*, O. Onal Tas, S. Bilir, & O. Plevne (2018)*Astrophys. Sp. Sc.*, in press (arXiv/1801.02170):Employs

`galpy.orbit`

integration in`MWPotential2014`

and the non-axisymmetric`DehnenBarPotential`

and`SteadyLogSpiralPotential`

to study the orbits of Milky-Way red-clump stars.

*The VMC survey XXVIII. Improved measurements of the proper motion of the Galactic globular cluster 47 Tucanae*, F. Niederhofer, M.-R. L. Cioni, S. Rubele, et al. (2018)*Astron. & Astrophys.*, in press (arXiv/1801.07738):Uses

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbit of the cluster 47 Tuc from a newly measured proper motion, finding that the orbit has an eccentricity of about 0.2 and reaches up to 3.6 kpc above the Galactic midplane.

*Characterising Open Clusters in the solar neighbourhood with the Tycho-Gaia Astrometric Solution*, T. Cantat-Gaudin, A. Vallenari, R. Sordo, F. Pensabene, A. Krone-Martins, A. Moitinho, C. Jordi, L. Casamiquela, L. Balaguer-Núnez, C. Soubiran, N. Brouillet (2018)*Astron. & Astrophys.*, submitted (arXiv/1801.10042):Employs

`galpy.orbit`

integration in`MWPotential2014`

to investigate the orbits of a sample of 128 open clusters with astrometry from the Tycho-*Gaia*Astrometric Solution.

*Fast estimation of orbital parameters in Milky-Way-like potentials*, J. Ted Mackereth & Jo Bovy (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1802.02592):Introduces the

`galpy.actionAngle.EccZmaxRperiRap`

and related`galpy.orbit.Orbit`

methods for the fast estimation of the orbital parameters (eccentricity, maximum vertical excursion, and peri/apocenter) in Milky-Way potentials. See this section of the documentation for more info.

*HI Kinematics Along The Minor Axis of M82*, Paul Martini, Adam K. Leroy, Jeffrey G. Mangum, Alberto Bolatto, Katie M. Keating, Karin Sandstrom, & Fabian Walter (2018)*Astrophys. J.*, in press (arXiv/1802.04359):Use

`galpy.potential`

components to create a mass model for M82 that consists of a`HernquistPotential`

bulge,`MN3ExponentialDiskPotential`

disk, and`NFWPotential`

dark-matter halo by matching photometric and rotation-curve data.

*Radial velocities of RR Lyrae stars in and around NGC 6441*, Andrea Kunder, Arthur Mills, Joseph Edgecomb, et al. (2018)*Astron. J.*, in press (arXiv/1802.09562):Employs

`galpy.orbit`

integration in`MWPotential2014`

to investigate a possible tidal stream for the globular cluster NGC 6441.

*The 4:1 Outer Lindblad Resonance of a long slow bar as a potential explanation for the Hercules stream*, Jason A. S. Hunt & Jo Bovy (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1803.02358):Uses

`galpy.potential`

modeling tools (`CosmphiDiskPotential`

and wrappers to grow it [`DehnenSmoothWrapperPotential`

] and make it rotate [`SolidBodyRotationWrapperPotential`

]) and disk models in`galpy.df`

to study the effect of the Milky Way bar’s hexadecapole (m=4) moment on the velocity distribution of stars in the disk of the Milky Way, finding that it can have a big effect near the 4:1 outer Lindblad resonance, which may be close to the Sun.

*KELT-22Ab: A Massive Hot Jupiter Transiting a Near Solar Twin*, Jonathan Labadie-Bartz, Joseph E. Rodriguez, Keivan G. Stassun, et al. (2018)*Astrophys. J.*, submitted (arXiv/1803.07559):Employs

`galpy.orbit`

integration in`MWPotential2014`

to explore the orbit of KELT-22A, the G2V host star of a transiting hot-jupiter exoplanet, in the Milky Way.

*Dissecting stellar chemical abundance space with t-SNE*, Friedrich Anders, Cristina Chiappini, Basílio X. Santiago, Gal Matijevič, Anna B. Queiroz, Matthias Steinmetz (2018)*Astron. & Astrophys.*, submitted (arXiv/1803.09341):Uses the

`galpy.actionAngle.EccZmaxRperiRap`

and related`galpy.orbit.Orbit`

methods introduced in Mackereth & Bovy (2018) to compute the eccentricity and maximum vertical excursion of a sample of solar-neighborhood stars with detailed chemical abundances, ages, and Galactic kinematics.

*Chemo-kinematics of the Milky Way from the SDSS-III MARVELS Survey*, Nolan Grieves, Jian Ge, Neil Thomas, et al. (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1803.11538):Employs

`galpy.orbit`

integration in a Milky-Way like potential (Miyamoto-Nagai disk, Hernquist bulge, and NFW dark-matter halo) to determine the eccentricity, maximum vertical excursion, and median Galactocentric radius of a sample of a few thousand solar neighborhood stars with spectra from the SDSS MARVELS survey.

*The demographics of neutron star - white dwarf mergers: rates, delay-time distributions and progenitors*, S. Toonen, H.B. Perets, A.P. Igoshev, E. Michaely, & Y. Zenati (2018)*Astron. & Astrophys.*, submitted (arXiv/1804.01538):Uses

`galpy.potential`

methods to build mass models for elliptical, dwarf elliptical, plus normal and bulgeless disk galaxies and`galpy.orbit`

integration to integrate the orbits of neutron-star–white-dwarf binaries kicked by the supernova explosion that created the neutron star, to investigate the spatial distribution of such binaries at the time of their mergers.

*Absolute HST Proper Motion (HSTPROMO) Catalog of Distant Milky Way Globular Clusters: Three-dimensional Systemic Velocities and the Milky Way Mass*, Sangmo Tony Sohn, Laura L. Watkins, Mark A. Fardal, Roeland P. van der Marel, Alis J. Deason, Gurtina Besla, & Andrea Bellini (2018)*Astrophys. J.*, submitted (arXiv/1804.01994):Employs

`galpy.orbit`

integration in a custom Milky-Way-like potential (a scaled version of`MWPotential2014`

) to study the orbits of 20 globular clusters in the Milky Way halo for which the authors measured new proper motions.

*Probing the nature of dark matter particles with stellar streams*, Nilanjan Banik, Gianfranco Bertone, Jo Bovy, & Nassim Bozorgnia (2018)*J. Cosmol. Astropart. Phys.*, submitted (arXiv/1804.04384):Uses

`galpy.df.streamdf`

and the galpy extension`galpy.df.streampepperdf`

to compute the effect of impacts from dark-matter subhalos on stellar streams when dark matter is warm, when there are many fewer such subhalos, and compares this to the standard CDM case.

*Connecting the Milky Way potential profile to the orbital timescales and spatial structure of the Sagittarius Stream*, Mark A. Fardal, Roeland P. van der Marel, David R. Law, Sangmo Tony Sohn, Branimir Sesar, Nina Hernitschek, & Hans-Walter Rix (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1804.04995):Employs the

`galpy.potential`

module to build models for the Milky Way’s gravitational potential and uses`galpy.orbit`

to integrate the orbits of members of the Sgr stream in a particle-spray model of the Sgr stream, to investigate how the Sgr stream is sensitive to the Milky Way’s potential.At this point, a flood of papers using

`galpy`

appeared, which we will not attempt to summarize:

*Evidence for accreted component in the Galactic discs*, Q. F. Xing. & G. Zhao (2018)*Mon. Not. Roy. Astron. Soc.*, in press (2018MNRAS.476.5388X)*The GALAH survey: An abundance, age, and kinematic inventory of the solar neighbourhood made with TGAS*, S. Buder, K. Lind, M. K. Ness, et al. (2018)*Astron. & Astrophys.*, submitted (arXiv/1804.05869)*The GALAH survey: Co-orbiting stars and chemical tagging*, Jeffrey D. Simpson, Sarah L. Martell, Gary Da Costa, et al. (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1804.05894)*Correlations between age, kinematics, and chemistry as seen by the RAVE survey*, Jennifer Wojno, Georges Kordopatis, Matthias Steinmetz, et al. (2018)*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1804.06379)*On the kinematics of a runaway Be star population*, Douglas Boubert & N. Wyn Evans (2018)*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1804.05849)*Unbiased TGAS×LAMOST distances and the role of binarity*, Johanna Coronado, Hans-Walter Rix, & Wilma H. Trick (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1804.07760)*The Origin of the 300 km/s Stream Near Segue 1*, Sal Wanying Fu, Joshua D. Simon, Matthew Shetrone, et al. (2018)*Astrophys. J.*, submitted (arXiv/1804.08622)*Anatomy of the hyper-runaway star LP 40-365 with Gaia*, R. Raddi, M. A. Hollands, B. T. Gaensicke, D. M. Townsley, J. J. Hermes, N. P. Gentile Fusillo, & D. Koester (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1804.09677)*Revisiting hypervelocity stars after Gaia DR2*, Douglas Boubert, James Guillochon, Keith Hawkins, Idan Ginsburg, & N. Wyn Evans (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1804.10179)*Gaia Proper Motions and Orbits of the Ultra-Faint Milky Way Satellites*, Joshua D. Simon (2018)*Astrophys. J.*, submitted (arXiv/1804.10230)*Three Hypervelocity White Dwarfs in Gaia DR2: Evidence for Dynamically Driven Double-Degenerate Double-Detonation Type Ia Supernovae*, Ken J. Shen, Douglas Boubert, Boris T. Gänsicke, et al. (2018)*Astrophys. J.*, submitted (arXiv/1804.11163)*Gaia DR2 Proper Motions of Dwarf Galaxies within 420 kpc: Orbits, Milky Way Mass, Tidal Influences, Planar Alignments, and Group Infall*, T. K. Fritz, G. Battaglia, M. S. Pawlowski, N. Kallivayalil, R. van der Marel, T. S. Sohn, C. Brook, & G. Besla (2018)*Astron. & Astrophys.*, submitted (arXiv/1805.00908)*The Lives of Stars: Insights From the TGAS-RAVE-LAMOST Dataset*, John J. Vickers & Martin C. Smith (2018)*Astrophys. J.*, in press (arXiv/1805.02332)*High precision pulsar timing and spin frequency second derivatives*, X. J. Liu, C. G. Bassa, & B. W. Stappers (2018)*Mon. Not. Roy. Astron. Soc.*, in press (arXiv/1805.02892)*The Galactic Disc in Action Space as seen by Gaia DR2*, Wilma H. Trick, Johanna Coronado, Hans-Walter Rix (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1805.03653):Uses

`galpy.actionAngle.actionAngleStaeckel`

to compute the actions in`galpy.potential.MWPotential2014`

of stars in the extended solar neighborhood in*Gaia*DR2.

*Tidal ribbons*, Walter Dehnen & Hasanuddin (2018)*Mon. Not. Roy. Astron. Soc.*, submitted (arXiv/1805.08481):Employs

`galpy.actionAngle.actionAngleStaeckel`

to compute the actions and frequencies of a disrupted satellite on an orbit close to the Galactic disk, to investigate the difference between the debris from such an orbit and from an orbit well within the halo.