J/ApJ/699/1454 YSOs around Cepheus B (Getman+, 2009)
Protoplanetary disk evolution around the triggered star-forming region Cepheus B. Getman K.V., Feigelson E.D., Luhman K.L., Sicilia-Aguilar A., Wang J., Garmire G.P. <Astrophys. J., 699, 1454-1472 (2009)> =2009ApJ...699.1454G
ADC_Keywords: X-ray sources ; Photometry, infrared ; Associations, stellar ; Stars, pre-main sequence ; Molecular clouds Keywords: ISM: individual (Cepheus B cloud) - open clusters and associations: individual (Cepheus OB3) - planetary systems: protoplanetary disks - stars: formation - stars: pre-main sequence - X-rays: stars Abstract: The Cepheus B (Cep B) molecular cloud and a portion of the nearby Cep OB3b OB association, one of the most active regions of star formation within 1kpc, have been observed with the Infrared Array Camera detector on board the Spitzer Space Telescope. The goals are to study protoplanetary disk evolution and processes of sequential triggered star formation in the region. Out of ∼400 pre-main-sequence (PMS) stars selected with an earlier Chandra X-ray Observatory observation, ∼95% are identified with mid-infrared sources and most of these are classified as diskless or disk-bearing stars. The discovery of the additional >200 IR-excess low-mass members gives a combined Chandra+Spitzer PMS sample that is almost complete down to 0.5M☉ outside of the cloud, and somewhat above 1M☉ in the cloud. Description: The X-ray observations of the Cep B/OB3b and their data analysis are described in detail by Getman et al. (2006, Cat. J/ApJS/163/306). The 30ks exposure was obtained on 2003 March 11.51-11.88 with the Advanced CCD Imaging Spectrometer (ACIS) detector on board NASA's Chandra X-ray Observatory as part of the ACIS Instrument Team's Guaranteed Time Observations (ObsId No. 3502, P.I.: G. Garmire). The mid-IR observation of Cep B and Cep OB3b was obtained on 2007 February 18 with the IRAC detector on NASA's Spitzer Space Telescope in the 3.6, 4.5, 5.8, and 8.0um channels. This is a General Observer project (program identification No. 30361; P.I.: J. Wang). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 159 431 Optical and IR photometry of X-ray sources table2.dat 55 431 Membership and classification of X-ray sources table3.dat 137 224 IR properties of non-Chandra IR-excess members
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) J/MNRAS/375/1220 : BVI photometry of young stars in 10 clusters (Mayne+, 2007) J/ApJS/163/306 : Chandra study of the Cep B star-forming region (Getman+, 2006) J/AJ/131/1574 : Infrared photometry of IC348 members (Lada+, 2006) J/MNRAS/341/805 : UBVI CCD photometry of Cep OB3b (Pozzo+, 2003) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [GFT2006] X-ray source number (1) 5- 9 F5.1 arcsec Off1 ?=-99 Optical-X-ray positional offset (2) 11- 16 F6.2 mag Vmag ?=-99 Magnitude in Johnson V-band (2) 18- 23 F6.2 mag e_Vmag ?=-99 Error in Vmag (2) 25- 30 F6.2 mag V-Ic ?=-99 V-Ic color index (2) 32- 37 F6.2 mag e_V-Ic ?=-99 Error in V-Ic (2) 39- 43 F5.1 arcsec Off2 ?=-99 2MASS-X-ray positional offset (3) 45- 50 F6.2 mag Jmag ?=-99 2MASS J-band magnitude 52- 57 F6.2 mag e_Jmag ?=-99 Error in Jmag 59- 64 F6.2 mag Hmag ?=-99 2MASS H-band magnitude 66- 71 F6.2 mag e_Hmag ?=-99 Error in Hmag 73- 78 F6.2 mag Ksmag ?=-99 2MASS Ks-band magnitude 80- 85 F6.2 mag e_Ksmag ?=-99 Error in Kmag 87- 92 A6 --- F1 2MASS photometry quality and confusion/contamination flag (see Cat. II/246) 94- 98 F5.1 arcsec Off3 ?=-99 IRAC-X-ray positional offset (4) 100-105 F6.2 mag [3.6] ?=-99 Spitzer/IRAC magnitude in 3.6-band 107-112 F6.2 mag e_[3.6] ?=-99 Error in [3.6] 114-119 F6.2 mag [4.5] ?=-99 Spitzer/IRAC magnitude in 4.5-band 121-126 F6.2 mag e_[4.5] ?=-99 Error in [4.5] 128-133 F6.2 mag [5.8] ?=-99 Spitzer/IRAC magnitude in 5.8-band 135-140 F6.2 mag e_[5.8] ?=-99 Error in [5.8] 142-147 F6.2 mag [8.0] ?=-99 Spitzer/IRAC magnitude in 8.0-band 149-154 F6.2 mag e_[8.0] ?=-99 Error in [8.0] 156-159 A4 --- F2 IRAC aperture photometry and confusion/contamination flag (5)
Note (1): For X-ray source positions see Table 1 of Getman et al. (2006, Cat. J/ApJS/163/306; <[GFT2006] NNN> in Simbad). Note (2): Optical data are from Mayne et al. (2007, Cat. J/MNRAS/375/1220). Note (3): For 2MASS source names see Table 2 of Getman et al. (2006; Cat. J/ApJS/163/306). Note (4): For the most of the sources the reported offset is for an IRAC source from the 3.6um-band image. When 3.6um data are not available, the reported offset is for an IRAC source from the 4.5um-band image. Note (5): Four digit flag (each digit for each of the 4 IRAC bands) presenting apertures of source photometry extraction and indicating relative degree of source contamination from nearby source(s) and extended IR emission: 2 = pixel aperture with likely high level of contamination, 3 = pixel aperture with likely moderate contamination, 4 = pixel aperture with likely low level of source contamination. 9 = inability to derive photometry due to the following possible reasons: * source may be out of channel's FOV (this is further clarified by the flag F5 from Table 2), * weak source (or no source) below the detection threshold, strong contamination/confusion from/with nearby source(s) or bright diffuse nebular emission.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [GFT2006] X-ray source number 5- 10 F6.2 --- alpha ?=-99 Observed SED slope α in IRAC bands α=dlog(λFλ)/log(λ) 12- 17 F6.2 --- e_alpha ?=-99 Error in alpha slope 19 I1 --- Nb [0/4] Number of IRAC bands used for slope determination 21- 25 F5.1 mag AJ ?=-99 J-band source extinction (6) 27- 31 F5.1 Msun Mass ?=-99 Stellar mass (6) 33- 35 A3 --- Mcl Membership and YSO class (7) 37- 38 A2 --- F3 TD: Flag indicating possible transition disk candidates (8) 40- 42 A3 --- F4 Flag indicating source position on IR color-color diagrams (9) 44- 50 A7 --- Region Source position projection region (G1) 52- 55 A4 --- F5 Flag indicating if source position is in/out of IRAC FOVs (10)
Note (6): J-band source extinction and stellar mass derived from the J versus J-H color-magnitude diagram by dereddening 2MASS photometric colors to the 3(2)Myr PMS isochrones for the CepOB3b/S155 (CepB) regions, assuming the distance of 725pc. Note (7): The membership is from Getman et al. (2006; Cat. J/ApJS/163/306) and the YSO class is derived here as follows: EXG = possible extragalactic contaminant; FRG = possible foreground contaminant; DSK = possible disk-bearing YSOs NoD = possible diskless YSOs (this is based on the comparison of the observed Cepheus SEDs with the reddened or dereddened median SEDs of YSOs in the IC 348 region (Lada et al.2006; Cat. J/AJ/131/1574) as described in the text); UNC = object of the uncertain class (however many of them are likely YSO members with unavailable or unreliable IR data). Note (8): This is based on our visual inspection of SEDs. Note (9): The three digit flag indicating source position on IR color-color diagrams. The first digit is for the 3.6-4.5 vs. 5.8-8.0 diagram, the second digit is for the 3.6-4.5 vs. 4.5-5.8 diagram, and the third digit is for the Ks-3.6 vs. 3.6-4.5 diagram. This flag may either warn about possible inconsistencies of YSO classifications based on our visual inspection of SEDs (Column "Class") with that of the color-color diagrams, or indicate interesting objects, such as transition object candidates: 0 = the YSO classification (Column "Class") is consistent with the formal loci of disk or diskless stars on a corresponding color-color diagram; 1 = disk-bearing YSO candidate (from Column "Class") is at the formal locus of diskless stars on the corresponding color-color diagram; 2 = diskless YSO candidate (Column "Class") is at the formal locus of disk-bearing stars on the corresponding color-color diagram; 3 = not a YSO member (Column "Class") or not enough information to place a member on the corresponding color-color diagram. Note (10): The four digit flag indicating if source position is outside the field of view of the one of the IRAC channels (each digit for each of the 4 IRAC channels): 0 = source is within the FOV of the corresponding IRAC channel; 1 = source is outside of the FOV of the corresponding IRAC channel.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq Non-X-ray source number (<[GFL2009b] NNN> in Simbad) 5- 13 F9.5 deg RAdeg Right ascension in decimal degrees (J2000) 15- 23 F9.6 deg DEdeg Declination in decimal degrees (J2000) 25- 30 F6.2 mag Jmag ?=-99 2MASS J-band magnitude 32- 37 F6.2 mag e_Jmag ?=-99 Error in Jmag 39- 44 F6.2 mag Hmag ?=-99 2MASS H-band magnitude 46- 51 F6.2 mag e_Hmag ?=-99 Error in Hmag 53- 58 F6.2 mag Kmag ?=-99 2MASS Ks-band magnitude 60- 65 F6.2 mag e_Kmag ?=-99 Error in Kmag 67- 72 A6 --- F1 2MASS photometry quality and confusion/contamination flag 74- 78 F5.2 mag [3.6] Spitzer/IRAC magnitude in 3.6-band 80- 83 F4.2 mag e_[3.6] Error in [3.6] 85- 89 F5.2 mag [4.5] Spitzer/IRAC magnitude in 4.5-band 91- 94 F4.2 mag e_[4.5] Error in [4.5] 96-100 F5.2 mag [5.8] Spitzer/IRAC magnitude in 5.8-band 102-105 F4.2 mag e_[5.8] Error in [5.8] 107-111 F5.2 mag [8.0] Spitzer/IRAC magnitude in 8.0-band 113-116 F4.2 mag e_[8.0] Error in [8.0] 118-124 A7 --- Region Source position projection region (G1) 126-130 F5.1 mag AJ ?=-99 J-band source extinction (2) 132-137 F6.2 Msun Mass ?=-99 Stellar mass (2)
Note (2): J-band source extinction and stellar mass derived from the J versus J-H color-magnitude diagram by dereddening 2MASS photometric colors to the 3(2)Myr PMS isochrones for the CepOB3b/S155 (CepB) regions, assuming the distance of 725pc.
Global Notes: Note (G1): The flag indicates on which region the source position is projected as follows: CepOB3b = area of the lightly absorbed Cepheus OB3b cluster; CepB = area of the portion of the molecular cloud, Cepheus B, with the embedded in it stellar cluster; S155 = HII interface between the molecular cloud and the Cepheus OB3b region.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Jul-2011
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