Study of exoplanets
(developed by C. Bot, T. Boch and P. Fernique)
Uses the VizieR and Simbad services and
This tutorial highlights the following functionalities: VizieR queries by UCDs, SIMBAD query by scripts, scripting in Aladin.
Find the data
- go to the VizieR webpage
- We want to look for exoplanets catalogs containing informations on the period. To do so:
- Query VizieR both by "Word matching" with the word "exoplanets" and by UCDs using the UCD TIME_PERIOD
- perform a joined query of table 2 and 3 from the catalog of nearby exoplanets (Butler+ 2006)
- select objects for which the minimum mass is greater than 8 Jupiter masses and the period is greater than 1000 days
- uncheck all columns except the position, the name of the stars, the period and the minimum mass (Msini)
- save the result as a TSV file that will be used later in Aladin
- go back one page
- uncheck all columns except the name of the stars
- uncheck the "compute""Position" box on top of the page, submit
- save as an ascii file
- you now have a list of identifier that will be used to Query SIMBAD by list
Now, you can either query SIMBAD by list or go directly to the "scripting with Aladin" item....
Query SIMBAD by list:
- go to the Simbad webpage
- go to the "identifier query" interface
- query a list of identifiers, using the ASCII file saved before
- click on the object having the greatest number of bibliographic references
- look at the basic data available, the references, but also the different types of measurements...
Query SIMBAD by script:
format object form1 "%IDLIST(1) : %COO(A D) %OTYPE \n%bibcodelist(2000-2010)[%*\n]\n"
set radius 0.2s
query around 55 Cnc
- Here is some explanations about this script:
- format object lets you define your own output format
- %IDLIST enables you to get all the existing identifiers for an object. In this example, one will only get the main identifier thanks to the "1" in the options ()
- the scripts is then asking to display the coordinates (%COO(A D)) and the main object type (%OTYPE) as defined in Simbad
- this script will also give all the bibliographical references on each object, published between 2000 and 2010. This is performed using the option %bibcodelist(2000-2010). The formating options [%*\n] will give a display of only one bibcode per line
- the line starting with set radius defines a research radius in a global manner (i.e. it will apply to all queries)
- Finally, once the format and the query radius are defined, you can specify all the identifiers that you wish to query. A line like "query around 55 Cnc" has to be written for each object to query. To query by coordinates, one could instead write query coo 00 24 20.278 -56 39 00.17
- Hint: you can get help on the script syntax and the existing options at http://simbad.u-strasbg.fr/simbad/sim-help?Page=sim-fscript
- complement this script by querying 2 or 3 objects of your choice, taken in the TSV file
- if you wish to mask the script display in the output, as well as the execution details, add the following two lines at the beginning of the script:
- execute the script with the "submit" button
- once the result has been displayed, copy the list of bibcodes obtained for an object and query the ADS service by pasting it in the Bibliographic Code Query form at http://cdsads.u-strasbg.fr/bib_abs.html and submit
Scripting in Aladin:
Goal : Generate sky charts for a list of objects => usage of Aladin script and macro :
- Launch Aladin;
- Load a DSS ESO image around HD30177, and activate the coordinate grid;
- Open the console (Menu Tool => Script Console) and see the corresponding script commands;
- In the console, execute this following script command: Data=get Simbad HD30177. See the result in the Aladin stack;
- Write this script in the macro editor (Menu Tool => Macro controller):
"ESO-$3" = get ESO(DSS) $1 $2
"Smb-$3" = get Simbad $1 $2
- To instanciate the parameters $1 $2 $3, load the TSV file generated by VizieR (Macro menu : File => Loads param);
- Increase the window width for seeing all columns, and select the fourth line (to skip the head);
- Test your script macro by clicking " Exec current params ". Verify that the charts has been correctly saved as a PNG image (by default, they will be save in the directory where Aladin is installed);
- Launch the script for all other objects;
- Modify the script for adding the USNOB VizieR catalog on each chart (see examples in menu Help => Help on script commands => get), and regenerate all charts.
The cdsclient package is a set of scripts allowing one to query VizieR catalogues from the command line.
The package is made of:
- vizquery which provides basically the same functionalities as the VizieR web interface, but through a command line interface
- a set of findXXX commands, for efficient querying of large catalogues (2MASS, USNO, UCAC, SDSS, etc)
The cdsclient tools can be easily installed on any Linux or Mac OS machine with a C compiler. Just follow the instructions of the section 4.1 of this page
. If you have troubles installing cdsclient, please ask one of the tutor for help.
In this exercise, we will first query by script the catalog of exoplanets, and then retrieve the infrared magnitudes for each exoplanet host star.
- to query the Butler+ catalogue of nearby exoplants, we use vizquery, providing our contraints ( Msini>8 and Per>1000). Type in a terminal window the following command :
vizquery -mime=tsv -source="J/ApJ/646/505/table2 J/ApJ/646/505/table3" -joincol=Name -sort=Dist "Msini=>8" "Per=>1000"
Here is a brief explanation of the different parameters:
- The -mime parameter lets us choose the format of the output. Other formats are available (ascii, fits, html, ...)
- The -source parameter is used to specify the table name (or list of tables) one wants to query. In our case, as we want to join two tables of the same catalogue, we have to specify with the -joincol parameter the column on which to perform the join
- The -sort parameter is used in our example to sort the matching sources by their distance (in parsec)
Note that the parameters with special characters (as >
) are quoted in order to keep the shell interpreter happy.
- using the -out and -out.add parameters, we can now specify that we only want the computed position (columns _RAJ2000 and _DEJ2000) in decimal degrees (option - in the output :
vizquery -mime=tsv -source="J/ApJ/646/505/table2 J/ApJ/646/505/table3" -joincol=Name -sort=Dist -out=None -out.add=_RAJ2000,_DEJ2000 -oc.form=deg "Msini=>8" "Per=>1000" > exoplanets_pos.txt
The output has been redirected to the file exoplanets_pos.txt
- In order to retrieve the IR magnitudes for the list of positions we have saved, we will use the find2mass command which may take a list of targets as an input:
find2mass -f exoplanets_pos.txt -rs 2 -e b
The parameter -e b
will output only the basic information for each source (position and magnitudes), instead of the whole record
If we increase the search radius (-rs parameter) to 100 (arcsec) for instance, several matches will be found for each input position.
For more information, ask the nearest tutor or refer to the following documentation pages:
- 10 May 2010