J/ApJ/712/925 Transition circumstellar disks in Ophiuchus (Cieza+, 2010)
The nature of transition circumstellar disks. I. The Ophiuchus molecular cloud. Cieza L.A., Schreiber M.R., Romero G.A., Mora M.D., Merin B., Swift J.J., Orellana M., Williams J.P., Harvey P.M., Evans N.J. <Astrophys. J., 712, 925-941 (2010)> =2010ApJ...712..925C
ADC_Keywords: Accretion ; Photometry, infrared ; Spectra, red ; YSOs ; Millimetric/submm sources ; Stars, double and multiple Keywords: binaries: general - circumstellar matter - protoplanetary disks - stars: pre-main sequence Abstract: We have obtained millimeter-wavelength photometry, high-resolution optical spectroscopy, and adaptive optics near-infrared imaging for a sample of 26 Spitzer-selected transition circumstellar disks. All of our targets are located in the Ophiuchus molecular cloud (d∼125pc) and have spectral energy distributions (SEDs) suggesting the presence of inner opacity holes. We use these ground-based data to estimate the disk mass, multiplicity, and accretion rate for each object in our sample in order to investigate the mechanisms potentially responsible for their inner holes. We find that transition disks are a heterogeneous group of objects, with disk masses ranging from <0.6 to 40MJUP and accretion rates ranging from <10-11 to 10-7M☉/yr, but most tend to have much lower masses and accretion rates than "full disks" (i.e., disks without opacity holes). Eight of our targets have stellar companions: six of them are binaries and the other two are triple systems. In four cases, the stellar companions are close enough to suspect they are responsible for the inferred inner holes. We find that nine of our 26 targets have low disk mass (<2.5MJUP) and negligible accretion (<10-11M☉/yr), and are thus consistent with photoevaporating (or photoevaporated) disks. Four of these nine non-accreting objects have fractional disk luminosities <10-3 and could already be in a debris disk stage. Seventeen of our transition disks are accreting. Thirteen of these accreting objects are consistent with grain growth. The remaining four accreting objects have SEDs suggesting the presence of sharp inner holes, and thus are excellent candidates for harboring giant planets. Description: We drew our sample from the 297 young stellar object candidates (YSOc) in the Ophiuchus catalog of the Cores to Disks (Evans et al. 2003PASP..115..965E) Spitzer Legacy Project. Millimeter interferometric observations of 24 of our targets were conducted in service mode with the SMA, on Mauna Kea, Hawaii, during the Spring and Summer of 2009 (April 6 through July 16). Millimeter wavelength observations of five of our targets were made with Bolocam at the CSO on Mauna Kea, Hawaii, during 2009 June 25-30. We obtained echelle spectroscopy (resolution >20000) for our entire sample, in 2009, using three different telescopes, Clay, CFHT, and Du Pont. All the spectra include the Hα line, which we use to derive accretion rates. High spatial resolution near-IR observations of our entire sample were obtained with the Nasmyth Adaptive Optics Systems (NAOS) and the CONICA camera at the 8.2m telescope Yepun, which is part the European Southern Observatory's (ESO) Very Large Telescope (VLT) in Cerro Paranal, Chile. The data were acquired in 2009 April 1 through September 30. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 136 34 Transition disk sample table2.dat 88 34 Observed properties table3.dat 84 34 Derived properties
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) J/A+A/515/A75 : Low-mass population in ρ Oph cloud (Alves de Oliveira+, 2010) J/A+A/519/A34 : YSOs in DROXO (Deep rho Oph XMM obs.) (Pillitteri+, 2010) J/ApJ/692/973 : Protostars in Perseus, Serpens and Ophiuchus (Enoch+, 2009) J/ApJ/703/1964 : Spectra of three nearby star-forming regions (Furlan+, 2009) J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009) J/ApJ/683/822 : Star formation in Ophiuchus and Perseus II. (Jorgensen+, 2008) J/A+A/485/155 : HK photometry of rho Oph PMS stars (Alves de Oliveira+, 2008) J/ApJ/686/L115 : Masses of evolved disks in PMS stars (Cieza+, 2008) J/ApJ/671/1800 : SCUBA observations of ρ Oph cloud (Andrews+, 2007) J/A+A/452/245 : Near-IR photometry of PMS stars in rho Oph (Natta+, 2006) J/A+A/429/963 : XMM-Newton observation of the rho Oph cloud (Ozawa+, 2005) J/ApJ/630/381 : Mid-IR imaging in ρ Oph (Barsony+, 2005) J/AJ/130/1733 : Optical spectroscopy of ρ Oph stars (Wilking+, 2005) J/PASJ/55/653 : Chandra X-ray flares in rho Ophiuchi (Imanishi+, 2003) J/ApJ/566/993 : rho Ophiuchus (Lynds 1688) cluster NICMOS imaging (Allen+, 2002) J/A+A/372/173 : ISOCAM observations of the rho Ophiuchi cloud (Bontemps+, 2001) http://irsa.ipac.caltech.edu/data/SPITZER/C2D/ : Spitzer c2d home page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Seq [1/34] Running sequence number 4- 9 A6 --- --- [SSTc2d] 11- 26 A16 --- SSTc2d Object Name from "Cores to Disks" catalog (JHHMMSS.s+DDMMSS) 28- 41 A14 --- AltName Alternative name 43- 47 F5.2 mag R1mag First R mag from USNO-B1 catalog 49- 53 F5.2 mag R2mag Second R mag from USNO-B1 catalog 55- 62 E8.2 mJy Jmag 2MASS J band magnitude (1) 64- 71 E8.2 mJy Hmag 2MASS H band magnitude (1) 73- 80 E8.2 mJy Ksmag 2MASS Ks band magnitude (1) 82- 89 E8.2 mJy F3.6 Spitzer/IRAC 3.6 micron band flux density (1) 91- 98 E8.2 mJy F4.5 Spitzer/IRAC 4.5 micron band flux density (1) 100-107 E8.2 mJy F5.8 Spitzer/IRAC 5.8 micron band flux density (1) 109-116 E8.2 mJy F8.0 Spitzer/IRAC 8.0 micron band flux density (1) 118-125 E8.2 mJy F24 Spitzer/MIPS 24 micron band flux density (1) 127 A1 --- l_F70 The 5σ limit flag on F70 129-136 E8.2 mJy F70 Spitzer/MIPS 70 micron band flux density (2)
Note (1): Detections are >7σ (i.e., the photometric uncertainties are <15%) Note (2): The 70 micron fluxes are either >5σ detections or 5σ upper limits.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Seq [1/34] Running sequence number 4- 12 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000) 14- 22 F9.5 deg DEdeg Declination in decimal degrees (J2000) 24- 30 A7 --- Tel Telescope used to obtain spectrum (Clay, CFHT or Du Pont) 32- 33 A2 --- SpT MK spectral type 35- 38 A4 0.1nm LiI ? LiI equivalent width; in Angstroms (3) 40- 42 A3 --- CaII [Yes/No ]? Presence of CaII emission 44- 46 I3 km/s Halpha ? Hα velocity dispersion at 10% peak intensity 47- 48 A2 --- f_Halpha [-1/No] Hα in emission (4) 50- 53 F4.2 mm mm The (sub)millimeter wavelength 55 A1 --- l_Fmm ? Upper limit flag for Fmm (3σ) 57- 62 F6.2 mJy Fmm The (sub)millimeter flux (5) 64- 68 F5.2 mJy e_Fmm ? The 1σ uncertainty for Fmm 70- 74 F5.3 arcsec Sep ? Companion separation (G1) 76- 81 F6.2 deg PA ? Position angle of companion 83 A1 --- l_dK ? Upper limit flag for dk (5σ) 85- 88 F4.2 mag dK ? Flux ratio of companion in the Ks band
Note (3): The absence of data implies that the signal to noise in this region of the spectrum is too low to measure the width or establish the presence of the LiI line. Note (4): A "-1" implies that Hα is seen in absorption. Note (5): The 1.3mm data for source #14 and 17 comes from Andrews & Williams (2007, Cat. J/ApJ/671/1800), while the 1.3mm and 850um data for sources #12, 13 and 27 comes from Cieza et al. (2008, Cat. J/ApJ/686/L115).
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Seq [1/34] Running sequence number 4 A1 --- l_accRate ? Upper limit flag for AccRate 6- 10 F5.1 [Msun/yr] accRate ? Accretion Rate (log scale) 12 A1 --- l_Mdisk ? Upper limit flag for DiskMass 14- 17 F4.1 Mjup Mdisk ? Disk Mass (6) 19- 24 F6.2 AU rProj ? Projected separation (G1) 26- 29 F4.2 um lam(to) λturnoff parameter (7) 31- 35 F5.2 --- alphaE αexcess parameter (7) 37 A1 --- l_log(Ld/L*) ? Upper limit flag for log(Ld/L*) 39- 44 A6 [-] log(Ld/L*) Fractional disk luminosity (log scale) 46- 48 F3.1 mag AJ Extinction in the J-band 50- 84 A35 --- OType Object type
Note (6): The disk mass upper limits for targets #12 and 27 come from Cieza et al. (2008, Cat. J/ApJ/686/L115). Note (7): the SED shape is quantified by the 2 parameters λturnoff (longest wavelength at which the observed flux is dominated by the stellar photosphere) and αexcess, slope of the IR excess.
Global notes: Note (G1): Source #12 is a binary identified by VLBA observations (Loinard et al. 2008ApJ...675L..29L). Source #24 is a triple system. The tight components are consistent with two equal-brightness objects with a separation of ∼0.05" and a ∼30 deg position angle (see Section 4.4 and Figure 4). Source #27 is a triple system. The "primary" star in the VLT observations is itself a spectroscopic binary with a 35.9d period (Mathieu, R.D. 1994ARA&A..32..465M).
History: From electronic version of the journal References: Romero et al. Paper II. 2012ApJ...749...79R Cat. J/ApJ/749/79 Cieza et al. Paper III. 2012ApJ...750..157C
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Apr-2012
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