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J/ApJ/660/1462      Abundances of ONC X-ray PMS stars        (Maggio+, 2007)
Coronal abundances in Orion nebula cluster stars.
    Maggio A., Flaccomio E., Favata F., Micela G., Sciortino S.,
    Feigelson E.D., Getman K.V.
   <Astrophys. J., 660, 1462-1479 (2007)>
   =2007ApJ...660.1462M
ADC_Keywords: Clusters, open; X-ray sources ; Stars, pre-main sequence ;
              Photometry ; Abundances
Keywords: stars: activity - stars: coronae - stars: late-type - X-rays: stars


Abstract:
    Following the Chandra Orion Ultradeep Project (COUP) observation, we
    have studied the chemical composition of the hot plasma in a sample of
    146 X-ray-bright pre-main-sequence stars in the Orion Nebula Cluster
    (ONC). We report measurements of individual element abundances for a
    subsample of 86 slightly absorbed and bright X-ray sources, using
    low-resolution X-ray spectra obtained from the Chandra ACIS
    instrument.

Description:
    The COUP data were obtained in 2003 January with the Advanced CCD
    Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory by
    combining six consecutive observations of the Orion Nebula Cluster
    (ONC) with the same aim point and roll angle. The resulting data set
    has a total exposure time of ∼838ks (9.7days), distributed over
    13.2days.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        84      146   Properties of Sample Stars
table2.dat        82       86   Spectral Analysis Results


See also:
    J/ApJS/160/319 : COUP: observations and source lists (Getman+, 2005)


Byte-by-byte Description of file: table1.dat

   Bytes Format Units   Label     Explanations

       1  A1    ---     S         [HL]  (L)ow- or (H)igh-Absorption Sample
   3-  6  I4    ---     COUP      COUP number (Cat. J/ApJS/160/319)
   8- 21  A14   ---     SpType    Spectral type
  23- 26  F4.2  solMass Mass      ?=- Stellar Mass
  28- 31  F4.2  [yr]    Age       ?=- Stellar Age (log scale)
  33- 36  F4.2  mag     AV        ?=- Absorption in V band
  38- 42  F5.2  mag     D(I-K)    ?=- Δ(I-K) near-infrared excess
  44- 48  F5.1  0.1nm   EW        ?=- Ca II equivalent width
  50- 54  F5.2  mag     Vmag      ?=- V magnitude
  56- 60  F5.2  mag     Imag      ?=- I magnitude
  62- 66  F5.2  mag     Jmag      ?=- J magnitude
  68- 72  F5.2  mag     Hmag      ?=- H magnitude
  74- 78  F5.2  mag     Ksmag     ?=- Ks magnitude
  80- 84  F5.2  mag     Lmag      ?=- L magnitude


Byte-by-byte Description of file: table2.dat

   Bytes Format Units     Label    Explanations

   1-  4  I4    ---       COUP     COUP number (Cat. J/ApJS/160/319)
   6-  8  F3.1  10+21cm-2 NH       Interstellar absorption H column density
  10- 12  F3.1  keV       T1       ?=- Plasma temperature of the first component
  14- 16  F3.1  keV       T2       Plasma temperature of the second component
  18- 21  F4.1  keV       T3       Plasma temperature of the third component
  23- 25  F3.1  m-5       k1       ?=- Volume emission measure for the first
                                       component, divided by 4πD2 (1)
  27- 30  F4.1  m-5       k2       ?=- Volume emission measure for the second
                                       component, divided by 4πD2 (1)
  32- 34  F3.1  m-5       k3       ?=- Volume emission measure for the third
                                       component, divided by 4πD2 (1)
  36- 38  F3.1  Sun       O        O abundance (in solar units)
  40- 42  F3.1  Sun       Ne       Ne abundance (in solar units)
  44- 46  F3.1  Sun       Mg       Mg abundance (in solar units)
  48- 50  F3.1  Sun       Si       Si abundance (in solar units)
  52- 54  F3.1  Sun       S        S abundance (in solar units)
  56- 58  F3.1  Sun       Ar       Ar abundance (in solar units)
  60- 62  F3.1  Sun       Ca       Ca abundance (in solar units)
  64- 66  F3.1  Sun       Fe       Fe abundance (in solar units)
  68- 70  F3.1  Sun       Ni       Ni abundance (in solar units)
  72- 74  F3.1  ---       Rchi2    Reduced χ2
  76- 78  I3    ---       DOF      Degrees of freedom
  80- 82  F3.1  10-16W/m2 fX       Absorbed source X-ray flux, in the 2-8keV
                                    (hard) band, in 10-13erg/cm2/s

Note (1): the volume emission measure is EM = n2V, where
     n is the electron number density and V the volume;
     D is the source distance. The result is in 10-10cm-5.


History:
    From electronic version of the journal
(End)                                      Patricia Vannier [CDS]    13-Mar-2009