iWander

Dynamics of Interstellar Wanderers

Presentation

This package is an implementation of the general method devised by Zuluaga et al. (2017) for assesing the origin of interstellar small bodies (asteroids and comets).

The package include data and tools that can be used in general for studying the dynamics of an interstellar vagabond object (small-body, interstellar spaceship and even stars).

If you use or adapt the package for any scientific purpose please refer to this paper:

Zuluaga,Sanchez-Hernandez, Sucerquia & Ignacio Ferrin, A general method for assesing the procedence of an interstellar small body: the case of 1I/´Oumuamuaa (1I/2017 U1), arXiv:1711.09397.

The paper is under review for publication in the Astronomical Journal.

NOTE As the revision process is undergoing, un updated version of the paper will be available in this link.

Progenitor Candidates

A list of the progenitor candidates of the interstellar object 1I/2017 U1 ('Oumuamua), identified using this method along with their corresponding origin probabilities are available (and will be updated) in this file.

NOTE: This list could change when better astrometric information or improvements on the methodology be available. Stay tuned!

Getting the package

You may obtain the package in different ways:

• Cloning anonymously the github repository:

  git clone http://github.com/seap-udea/iWander.git
  

• Downloading the tarball of the latest release:

  wget http://github.com/seap-udea/iWander/archive/master.zip
  

• Cloning the package as a developer (credentials required):

  git clone git@github.com:seap-udea/iWander.git
  

The size of the package is large (several hundreds of MBs). This is mainly due to the data required to run some of the modules.

Installation

For installing the package run:

bash install.sh

The installation script performs several operations required to start using the package:

1. Copy the template files in the util/conf directory to the root package directory.

2. Install the required linux and python packages.

3. Unpack large files. Large files are splitted in 20MB chunks of data inside the .store directory.

4. Attempt to compile a small test program. If compilation fails comment/uncomment the proper line in the file compiler.in:

   ###################################################
   #CHOOSE YOUR ARCHITECTURE
   ###################################################
   #ARCH=32
   ARCH=64
   

Quickstart

1. Prepare the configuration file for the object and place it in the objects directoy. See the already available examples there (Oumuamua, Voyager 1 and Voyager 2).

2. Edit the general configuration files iwander.conf and wanderer.conf for setting up the name of the wanderer and its properties.

3. Compile the key programs:

   make all
   

4. Generate the surrogate objects and propagate them until the time of ingress.

   bash bin/run.sh wanderer.exe
   

5. Compute the minimum distance to all the stars in the input catalog and select the candidates.

   bash bin/run.sh encounters.exe
   

6. Find progenitor candidates and compute their origin probability:

   bash bin/run.sh probability.exe
   

The output of this process is the file progenitors-<wanderer>.csv having a list of the progenitor candidates with their respective origin probability.

Optionally you can:

6. Generate the table of ingress properties:

   python3 bin/ingress.py
   

7. Sort out the candidates according to position probability or minimum distance:

   python3 bin/progenitors.py
   

Advanced usage

If you want to use the package to run a full analysis, follow this procedure:

1. Go to the JPL Small Body Database and get the information about the latest orbit of the object. Activate the link of the covariance matrix. Open a file objects/<object>.jpl and copy the content of the object information starting in "Orbital Elements..." and finishing in the last line of the covariance matrix. The file may looks like:

        Orbital Elements at Epoch 2458059.5 (2017-Nov-02.0) TDB
        Reference: JPL 15 (heliocentric ecliptic J2000)
         Element   Value  Uncertainty (1-sigma)   Units 
        e	   1.199512420116502  0.00018113   
        a	   -1.27983608372505  0.0008246	   au
        q	   .2553431944164106  6.7314e-05   au
        i	   122.6872051262465  0.0063195	   deg
        node	   24.59921097817111  0.00028668   deg
        peri	   241.7029828623324  0.012299	   deg
        M	   36.42531274372935  0.034202	   deg
        tp	   2458005.990518697340
        (2017-Sep-09.49051870)	0.0014726	JED
        period			n/a
        n/a			n/a
        n/a			d
        yr
        n	.6807263284370244	0.00065789	deg/d
        Q	n/a			n/a		au
                Orbit Determination Parameters
           # obs. used (total)        121  
           data-arc span   	        34 days  
           first obs. used   		  2017-10-14  
           last obs. used   		    2017-11-17  
           planetary ephem.   		      DE431  
           SB-pert. ephem.   		        SB431-N16  
           fit RMS   				  .38413  
           data source   			    ORB  
           producer   				      Davide Farnocchia  
           solution date   			        2017-Dec-11 10:08:04  
   
        Additional Information
         Earth MOID = .0958594 au 
         Jupiter MOID = 1.45505 au 
        [ hide covariance matrix ]
        Orbit Covariance (66)
              e		 q	tp	node	peri	i
        e     3.280884553475304E-8	1.21912468929939E-8	2.664024406876134E-7	-5.189060293792596E-8	2.227693306244164E-6 1.144454622346664E-6
        q     1.21912468929939E-8	4.531200156459704E-9	9.891692479282223E-8	-1.928718768663412E-8	8.27864377331905E-7  4.252549738508278E-7
        tp    2.664024406876134E-7	9.891692479282223E-8	2.168536853038564E-6	-4.208530841352833E-7	1.808283451109792E-5 9.292602259502882E-6
        node  -5.189060293792596E-8	-1.928718768663412E-8	-4.208530841352833E-7	8.218549627815087E-8	-3.523689281349856E-6 -1.809652625670336E-6
        peri  2.227693306244164E-6	8.27864377331905E-7	1.808283451109792E-5	-3.523689281349856E-6	.0001512656277515969  7.770714168110806E-5
        i     1.144454622346664E-6	4.252549738508278E-7	9.292602259502882E-6	-1.809652625670336E-6	7.770714168110806E-5  3.993643141790152E-5
              e				q			tp			W			w		      i
   

2. Convert the input file from the jpl format to the iwander format:

   python3 bin/JPL2iWander.py Oumuamua "1I/2017 U1 ('Oumuamua)"
   

   This will generate a file objects/Oumuamua.conf in the proper format for the package.

3. Calculate the properties of the ingress conditions for the object:

   bash bin/run.sh wanderer.exe
   

   The script run.sh launch the program. The standard output will be redirected to log/wanderer-<object>.log and the standard error to log/wanderer-<object>-detailed.log.

4. Generate the table with the ingress conditions:

   python3 bin/ingress.py
   

   This will create a table in LaTeX with a summary of the ingress conditions.

5. Generate the list of candidate stars including the encounter conditions with the LMA approximation.

   bash bin/run.sh encounters.exe
   

6. Run the probability analysis in parallel:

   bash bin/probability.sh NSPLIT=10 MAXPROC=2
   

7. Monitor the advance of the parallel job:

   bash bin/monitor.sh
   

8. Join the results:

   python bin/join.py 
   

Alternatively you can simply run a single process

```
bash bin/run.sh probability.exe 
```

11. Once you have the results you may generate a final report:

    python3 bin/progenitor.py 
    

Structure of the package

The package is made of three type of components: programs, scripts and databases.

Programs are used to compute the core functions (propagate wanderers, find encounters, compute interstellar origin probabilities, etc.)

Scripts are used for pre and post processing of the information required or produced by the package.

Databases contain the information required to run some of the functionalities of the package.

Components

• wanderer: This program integrate the orbit of a moving object inside the Solar System.

  • Function:

    This program perform three different tasks:

    1. Calculate the time t_asy when the single conic approximation is good enough to predict the future position of the interstellar object.

    2. Calculate the time t_ing at which the object was at a distance equivalent to the truncation tidal radius of the Solar System.

    3. Predict the position and velocity of the surrogate objects at t_ing.

  • Input: None

  • Output:

    • wanderer-<object>.csv: properties of all the surrogate objects.

    • ingress-<object>.dat: a summary of the ingress orbit properties including the epoch of asymptotic elements and their covariance matrix, the time of ingress, the radiant and velocity at ingress.

• encounters: This program integrate the orbit of a moving object inside the Solar System.

  • Function:

    This program perform two different tasks:

    1. Compute the LMA minimum distance and time to all stars in the AstroRV catalogue...

    2. Select the progenitor candidates.

  • Input:

    • wanderer-<object>.csv

    Output:

    • encounters-<Wanderer>.csv: all the columns of the input catalog (AstroRV) plus additional information computed from the LMA approximation.

    • candidates-<Wanderer>.csv: list of objects fulfilling certain selection criteria that classify them as close encounters candidates.

• probability: This program integrate the orbit of a moving object inside the Solar System.

  • Function:

    Calculate the IOP for a list of stellar candidates.

  • Input:

    • wanderer-<object>.csv

    • candidates-<object>.csv

  • Output:

    • progenitors-<object>.csv

For the developer

iWander uses GSL and Spice as backbone utility libraries. The latest precompiled version of both libraries, along witth the header files are provided with the package in the util directory.

Input parameters are passed to the programs using a configuration file <programa.conf>. The configuration file has the structure of a C program. The declarations and actions in the program are included directly into the main of the corresponding program.

Naming conventions:

• Configuration variables: Capitalized. Example: Wanderer, Npart.

• Macros and global variables: Fully capital. Example: FILENAME, REARTH.

• Routines: Umbrella style. Example: vectorAllocate, integrateEOM.

• Local variables: Free naming rules.

Acknowledgements

This package has been developed thanks to the incredible work made by previous scientist and developers. Most of the work of those who make this package possible has been cited in our papers. Others are mentioned in the software itself.

License

Copyright (C) 2017 Jorge I. Zuluaga, Oscar Sanchez-Hernandez, Mario Sucerquia & Ignacio Ferrin

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and the databases associated (the "Package"), to deal in the Package without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Package, and to permit persons to whom the Package is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Package. A reference to the Package shall be included in all scientific publications that make use of the Package.

THE PACKAGE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE DATABASE OR THE USE OR OTHER DEALINGS IN THE DATABASE.