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J/ApJ/703/1964    Spectra of three nearby star-forming regions   (Furlan+, 2009)
Disk evolution in the three nearby star-forming regions of Taurus, Chamaeleon,
and Ophiuchus.
    Furlan E., Watson D.M., McClure M.K., Manoj P., Espaillat C., D'Alessio P.,
    Calvet N., Kim K.H., Sargent B.A., Forrest W.J., Hartmann L.
   <Astrophys. J., 703, 1964-1983 (2009)>
   =2009ApJ...703.1964F
ADC_Keywords: Molecular clouds ; Spectra, infrared ; YSOs

Keywords: circumstellar matter - infrared: stars - stars: formation -
          stars: pre-main sequence

Abstract:
    We analyze samples of Spitzer Infrared Spectrograph spectra of T Tauri
    stars in the Ophiuchus, Taurus, and Chamaeleon I star-forming regions,
    whose median ages lie in the <1-2Myr range. The median mid-infrared
    spectra of objects in these three regions are similar in shape,
    suggesting, on average, similar disk structures. When normalized to
    the same stellar luminosity, the medians follow each other closely,
    implying comparable mid-infrared excess emission from the
    circumstellar disks. We use the spectral index between 13 and 31um and
    the equivalent width of the 10um silicate emission feature to identify
    objects whose disk configuration departs from that of a continuous,
    optically thick accretion disk. Based on their medians and fraction of
    evolved disks, T Tauri stars in Taurus and Chamaeleon I are very
    alike.

Description:
    Our Taurus, Chamaeleon I, and Ophiuchus targets were observed as part
    of an IRS guaranteed-time program during IRS campaigns 3, 4, 12, 19,
    20, 21, 22, 23, 29, and 30, which were scheduled from 2004 February to
    2006 April. The objects (table 5) were originally selected from
    infrared catalogs of YSOs in these regions that were compiled before
    the launch of the Spitzer Space Telescope in 2003. All targets were
    observed with either the two low-resolution IRS modules (Short-Low
    (SL) and Long-Low (LL), 5.2-14um and 14-38um, respectively) or the SL
    module and the two high-resolution modules (Short-High (SH) and
    Long-High (LH), 10-19um and 19-37um, respectively). In this way, we
    obtained the full mid-infrared spectrum from 5 to 40um for each target.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        45       63   Properties of the targets in the Ophiuchus core
                             region
table2.dat        45       85   Properties of the targets in the Taurus region
table3.dat        45       69   Properties of the targets in the Chamaeleon I
                             region
table4.dat        45       15   Properties of the targets in the Ophiuchus
                             off-core region
table5.dat        46      233   Target names and coordinates
table6a.dat       40      310   Ophiuchus core median (H normalization)
table6b.dat       40      310   Chamaeleon I median (H normalization)
table6c.dat       40      310   Taurus median (H normalization)


See also:
 II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
 II/156 : IRAS Faint Source Catalog, |b| > 10, Version 2.0 (Moshir+ 1989)
 V/73   : Emission-Line Stars of the Orion Population (Herbig+ 1988)
 J/A+A/519/A34  : YSOs in DROXO (Deep rho Oph XMM obs.) (Pillitteri+, 2010)
 J/A+A/515/A75  : Low-mass population in ρ Oph cloud (Alves de Oliveira+,
                  2010)
 J/ApJ/692/973  : Protostars in Perseus, Serpens and Ophiuchus (Enoch+, 2009)
 J/PASJ/60/209  : Faint companions around YSOs in TMC (Itoh+, 2008)
 J/ApJ/683/822  : Star formation in Ophiuchus and Perseus II. (Jorgensen+, 2008)
 J/ApJS/173/104 : Stellar population in Chamaeleon I (Luhman, 2007)
 J/A+A/452/245  : Near-IR photometry of PMS stars in rho Oph (Natta+, 2006)
 J/A+A/460/695  : Search for Associations Containing Young stars (Torres+, 2006)
 J/AJ/130/1733  : Optical spectroscopy of ρ Oph stars (Wilking+, 2005)
 J/AJ/126/2971  : UBVRI photometry of 131 Herbig Ae/Be (Vieira+, 2003)
 J/A+A/372/173  : ISOCAM observations of the rho Ophiuchi cloud (Bontemps+,
                  2001)
 J/A+A/357/219  : ISOCAM observations in Cha I. (Persi+, 2000)
 J/ApJS/112/109 : Rho Oph Near-IR Positions and Photometry (Barsony+, 1997)
 J/ApJS/101/117 : UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995)


Byte-by-byte Description of file: table1.dat table2.dat table3.dat table4.dat

   Bytes Format Units   Label     Explanations

   1- 20  A20   ---     Name      Target name
  22- 26  A5    ---     SpT       Adopted MK spectral type (1)
  28- 31  F4.1  ---     Av        ? Optical extinction A_V_ (assuming R_V_=3.1) (2)
  33- 37  F5.2  um      EW        ? The 10um equivalent width in um
  39- 43  F5.2  ---     n13-31    ? The 13-31um spectral index (n13-31)
      45  A1    ---     Med       [x]? x: the object was used in the median 
                              calculation

Note (1): Spectral types were taken from references below:
 * In table 1: from Brandner & Zinnecker (1997A&A...321..220B);
   Luhman & Rieke (1999ApJ...525..440L); 
   Wilking et al. (2005, Cat. J/AJ/130/1733);
   Natta et al. (2006, Cat. J/A+A/452/245); 
   McClure et al.  (2010ApJS..188...75M); 
 * In table 2: from Kenyon et al. (1990AJ.....99..869K);
   Hartigan et al.  (1994ApJ...427..961H); 
   Strom & Strom (1994ApJ...424..237S);
   Kenyon & Hartmann (1995, Cat. J/ApJS/101/117); 
   Torres et al.  (1995AJ....109.2146T); 
   Kenyon et al. (1998AJ....115.2491K); 
   Briceno et al. (1998AJ....115.2074B); 
   Luhman (2000ApJ...544.1044L);
   White & Ghez (2001ApJ...556..265W); 
   Hartigan & Kenyon (2003ApJ...583..334H); 
   White & Basri (2003ApJ...582.1109W); 
   White & Hillenbrand (2004ApJ...616..998W); 
   Calvet et al.  (2004AJ....128.1294C); 
   Furlan et al. (2006ApJS..165..568F).
 * In table 3: spectral type and, where available, extinction information 
   were taken from Luhman (2004ApJ...602..816L) and Gomez & Mardones
   (2003AJ....125.2134G). For objects without published or with uncertain
   extinction values, the optical extinction AV was derived using the 
   observed optical/near-infrared colors and intrinsic colors based on 
   the spectral type or a typical CTTS excess (see the text for details).
 * In table 4: spectral types were taken from Herbig & Bell (1988, Cat. V/73); 
   Chen et al. (1995ApJ...445..377C); 
   Preibisch et al. (1998, Cat. J/A+A/333/619); 
   Vieira et al. (2003, Cat. J/AJ/126/2971); 
   Torres et al. (2006, Cat. J/A+A/460/695);
   McClure et al.  (2010ApJS..188...75M).
Note (2): Uncertainties in AV are detailing below:
 * In table 1: uncertainties in AV, ranging from 1% to 30% of the AV value 
   (McClure et al. 2010ApJS..188...75M), account for ∼25% of the error
   bars of EW(10um) and n13-31.
 * In table 2: uncertainties in AV, assumed to be 0.3mag (Kenyon & Hartmann 
   1995, Cat. J/ApJS/101/117), account for ∼15% and 1% of the error bars 
   of EW(10um) and n13-31, respectively.
 * In table 3: uncertainties in AV, assumed to be 0.46mag (Luhman 2007,
   Cat. J/ApJS/173/104), account for ∼10% and 2% of the error bars of
   EW(10um) and n13-31, respectively.
 * In table 4: uncertainties in AV, which are typically 0.3mag
   (McClure et al.  2010ApJS..188...75M), account for ∼10% and 1% of the
   error bars of EW(10um) and n13-31, respectively.


Byte-by-byte Description of file: table5.dat

   Bytes Format Units   Label     Explanations

   1- 20  A20   ---     Name      Target name
  23- 24  I2    h       RAh       Hour of Right Ascension (J2000) (3)
  26- 27  I2    min     RAm       Minute of Right Ascension (J2000)
  29- 33  F5.2  s       RAs       Second of Right Ascension (J2000)
      36  A1    ---     DE-       Sign of the Declination (J2000) (3)
  37- 38  I2    deg     DEd       Degree of Declination (J2000)
  40- 41  I2    arcmin  DEm       Arcminute of Declination (J2000)
  43- 46  F4.1  arcsec  DEs       Arcsecond of Declination (J2000)

Note (3): Objects with 4h<RA<5.5h are in Taurus,
          objects with 10h<RA<12h are in Chamaeleon I,
          objects with 16h<RA<17h are in Ophiuchus.


Byte-by-byte Description of file: table6[abc].dat

   Bytes Format Units   Label     Explanations

   1-  4  F4.1  um      lambda    Wavelength in micron
   8- 16  E9.3  mW/m2   nuFnu     Median flux density νF_ν_ (1)
  20- 28  E9.3  mW/m2   e_nuFnu   Lower quartile in nuFnu (1)
  32- 40  E9.3  mW/m2   E_nuFnu   Upper quartile in nuFnu (1)

Note (1): These are the median, lower quartile, and upper quartile for the
     Ophiuchus core (L1688), Chamaeleon I and Taurus calculated using the
     IRS spectra of 28, 28 and 52 Class II objects, respectively, with
     K5-M2 spectral types, normalized at their 2MASS H-band fluxes.


History:
    From electronic version of the journal
(End)                 Greg Schwarz [AAS], Emmanuelle Perret [CDS]    02-Nov-2011