Science Question

What is the origin of the X-ray emission in young stars?


Focus in a star formation region, Orion Nebula Search for X-ray sources and retrieve their flux

Search for their infrared counterparts and retrieve J band magnitude, then observe the correlation of X-ray flux and J magnitude 

Compare to known relation Lx ~ Lbol in star formation regions indicating that X-ray emission is due to magnetic fields on the starsʼ surface

Using seleste

Search the Chandra Catalog for sources in a 1 arcmin box in the Orion Nebula and retrieve their flux

Search for sources in the twomass catalog with a 1 arcsec radius from each found Chandra source and retrieve their magnitude

Plot the two magnitudes and observe a correlation 

Step by Step

1. Download and start seleste

    Click on Launch

    Allow the application to access the computer

2. The application starts in the Guide mode

    Click on the Form icon to start building a query

3. Click on Services and select  Chandra Source Catalog

    Open the master_source table in the Contents area on the left.

    Select ra, dec, flux_aper90_b and add in the Output Columns area.

    Select err_ellipse_r0, add in the Column Criteria and set < 3 to select on-axis sources

    Add the following Column Criteria for 1 arcmin area in Orion 

    (ra < 83.82) AND ra > 83.8) AND (dec < -5.3) AND dec > -5.5)

    Hit Submit.

4. In the Jobs window, once the job status shows as Pending hit Run

    When the status becomes Completed view the results and hit Save to save them in a file e.g. csc_orion.xml

5. Return to the Query form and under services select GAVO Data Center TAP Service

    Hit Upload and upload the table of previously saved Chandra sources e.g. csc_orion.xml, it will appear

    as TAP_UPLOAD.user_table in Contents.

    Select user_table and add in Output Columns

    From twomass select raj2000, dej2000, jmag and add in Output Columns


6. Add a Position Search

    Select from drop down menu

    Select Center around: Other table and Select Table TAP_UPLOAD.user_table

    Set Radius 1.0 arcsec


7. In the Jobs window hit run

    Start Topcat

    When job is completed send results to Topcat

    Scatter plot log(flux_aper90_b) vs jmag and observe the correlation


© 2012 Smithsonian Astrophysical Observatory