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J/AJ/135/966    Circumstellar disk evolution in NGC 2068/71    (Flaherty+, 2008)

Evidence for early circumstellar disk evolution in NGC 2068/71. Flaherty K.M., Muzerolle J. <Astron. J., 135, 966-983 (2008)> =2008AJ....135..966F
ADC_Keywords: Accretion ; YSOs ; Spectroscopy ; Photometry, infrared ; Photometry, SDSS ; Extinction ; Radial velocities ; Rotational velocities Keywords: circumstellar matter - ISM: individual (NGC 2068, NGC 2071) - planetary systems: protoplanetary disks - stars: formation - stars: pre-main sequence Abstract: We study the disk and accretion properties of young stars in the NGC 2068 and NGC 2071 clusters. Using low-resolution optical spectra, we define a membership sample and determine an age for the region of ∼2Myr. Using high-resolution spectra of the Hα line we study the accretion activity of these likely members and also examine the disk properties of the likely members using IRAC and MIPS mid-infrared photometry. A substantial fraction (79%) of the 67 members have an infrared excess while all of the stars with significant infrared excess show evidence for active accretion. We find three populations of evolved disks (IRAC weak, MIPS weak, and transition disks) all of which show decreased accretion activity in addition to the evidence for evolution in the dust disk. Description: Low-resolution optical spectra were taken with the Hectospec instrument on the MMT (Multiple Mirror Telescope, Mount Hopkins, USA), in 2004 November 5 and 2005 October 23. High-resolution optical spectra were taken with the Hectochelle instrument on the MMT. Two fields, each with an exposure time of 3x1200s, were observed on 2004 December 3, 2005 and November 14. Near-infrared JHKs photometry was taken from the Two Micron All Sky Survey (2MASS, Cat. II/246). Mid-infrared photometry was obtained using the IRAC and MIPS cameras aboard the Spitzer Space Telescope. Optical photometry was taken from the Sloan Digital Sky Survey (SDSS, Cat. II/294); the Orion field was observed as part of an early calibration run through the Galactic plane in the fall of 1998 and the fall of 1999. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 119 69 Photometry of likely members table2.dat 63 69 Cluster members identified from low-resolution spectra table3.dat 61 67 Stellar parameters for likely members table4.dat 50 34 High-resolution spectra of likely members
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) J/AJ/129/907 : New Ori OB1 members (Briceno+, 2005) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 I4 --- [FM2008] Object identification number 6- 11 F6.3 mag gmag ? SDSS g band magnitude (1) 13- 18 F6.3 mag rmag ? SDSS r band magnitude (1) 20- 25 F6.3 mag imag ? SDSS i band magnitude(1) 27- 32 F6.3 mag zmag ? SDSS z band magnitude(1) 34- 39 F6.3 mag Jmag 2MASS J band magnitude 41 A1 --- f_Jmag [a] Unresolved source (2) 43- 48 F6.3 mag Hmag 2MASS H band magnitude 50- 55 F6.3 mag Ksmag 2MASS KS band magnitude 57- 62 F6.3 mag 3.6mag Spitzer/IRAC 3.6 micron band magnitude 64- 68 F5.3 mag e_3.6mag Uncertainty in 3.6mag 70- 75 F6.3 mag 4.5mag Spitzer/IRAC 4.5 micron band magnitude 77- 81 F5.3 mag e_4.5mag Uncertainty in 4.5mag 83- 88 F6.3 mag 5.8mag Spitzer/IRAC 5.8 micron band magnitude 90- 94 F5.3 mag e_5.8mag Uncertainty in 5.8mag 96-101 F6.3 mag 8.0mag Spitzer/IRAC 8.0 micron band magnitude 103-107 F5.3 mag e_8.0mag Uncertainty in 8.0mag 109-113 F5.3 mag 24mag ? Spitzer/MIPS 24 micron band magnitude 115-119 F5.3 mag e_24mag ? Uncertainty in 24mag
Note (1): SDSS u band data is not reported here because of the red leak in the filter. Note (2): 'a' indicates that the source is not resolved from a nearby star in the J band and only an upper limit is reported.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- [FM2008] Object identification 5- 7 A3 --- n_[FM2008] [a-d, ] Individual notes (1) 9- 10 I2 h RAh Hour of right ascension (J2000) 12- 13 I2 min RAm Minute of right ascension (J2000) 15- 19 F5.2 s RAs Second of right ascension (J2000) 21 A1 --- DE- Declination sign (J2000) 22- 23 I2 deg DEd Degree of declination (J2000) 25- 26 I2 arcmin DEm Arcminute of declination (J2000) 28- 32 F5.2 arcsec DEs Arcsecond of declination (J2000) 34- 38 A5 --- SpR Spectral type range 39 A1 --- f_SpR [c] indicates continuum stars (2) 41- 44 A4 --- SpT ?=- Spectral type adopted 46- 50 F5.1 0.1nm EWHa Hα equivalent width 52 A1 --- l_EWLi Limit flag on EWLi 53- 57 F5.2 0.1nm EWLi Lithium equivalent width 59- 63 A5 --- OType T-Tauri type (CTTS or WTTS)
Note (1): Flag as follows: a = [OI] 6300Å emission detected in optical spectra. b = Variable in the optical as observed by Briceno et al. (2005, Cat. J/AJ/129/907). They measured a spectral type of K6, and Hα and Li EWs of 98 and 0.4Å respectively. c = Binary from Padgett et al. (1997ApJ...477..705P). d = X-ray emission detected by Skinner et al. (2007ApJ...658.1144S). Note (2): continuum stars do not show any significant features that could be used to derive a spectral type.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 4 I4 --- [FM2008] Object identification 5 A1 --- f_[FM2008] [a] Possible contamination (1) 7- 11 F5.3 solLum Lum Luminosity (2) 13- 16 I4 K Teff Effective temperature (2) 18- 21 F4.2 solMass Mass Mass 23- 27 F5.3 solRad Rad Radius (3) 29- 31 F3.1 --- Av Extinction 32 A1 --- f_Av [b] no available optical photometry (4) 34 A1 --- l_Acc Limit flag on Acc 35- 39 F5.2 10-8Msun/yr Acc ?=- Accretion rate (5) 40 A1 --- f_Acc [cn] Flag on Acc (6) 42- 46 F5.2 --- alpha Slope of the SED in the IRAC bands (7) 48- 61 A14 --- Disk Disk descriptor (8)
Note (1): 'a' indicates that the Photometry may be contaminated by background source with very cool SED, possible a Class 0/I source. Note (2): The typical uncertainty in effective temperature is 5%, while the typical uncertainty in luminosity, which includes uncertainty in Teff and photometric uncertainty, is 10%. Note (3): derived assuming L=4πR2σT4eff. Note (4): 'b' indicates that, with no available optical photometry, and extended emission contaminating the 2MASS photometry, an accurate extinction could not be derived and we assume a lower limit of 0. Note (5): If the Hα profile indicates no active accretion then a 0 is used. If no high-resolution spectrum is available, then no number is reported. Note (6): Flag as follows: c = R-band magnitude from Siess et al. (2000A&A...358..593S) 2Myr isochrone used instead of the observed R-band magnitude to derive the accretion rate from veiling. n = no stand. Note (7): SED slope, α, from a least-squares fit of a power-law (λ.Fλ∝λα) of the four IRAC bands for each star Note (8): Disk descriptors as follows: Strong = (αIRAC>-1.6,[8.0]-[24]>2.4), MIPS-weak = (αIRAC←1.6,[8.0]-[24]<2.4), IRAC weak = (-1.6>αIRAC>-2.5), Gap = small short wavelength excess, large [24] excess, No = no disk (αIRAC←2.5).
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 4 I4 --- [FM2008] Object identification number 5 A1 --- f_[FM2008] [b] P Cygni profile (1) 7- 10 F4.1 km/s RV ?=- Radial velocity 12- 14 F3.1 km/s e_RV ? Radial velocity uncertainty 16 A1 --- l_vsini Limit flag on vsini 17- 20 F4.1 km/s vsini ?=- Rotational velocity 22- 25 F4.1 --- R ?=- Tonry & Davis (1979AJ.....84.1511T) R value (2) 27- 29 I3 km/s HaFW1 Hα full width 10%, 1st measure 31- 33 I3 km/s HaFW2 ? Hα full width 10%, 2nd measure 35- 39 F5.1 0.1nm HaEW1 Hα equivalent width, 1st measure 41- 44 F4.1 0.1nm HaEW2 ? Hα equivalent width, 2nd measure 46 A1 --- l_r Limit flag on r 47- 50 F4.2 --- r ?=- Veiling (r=Fexcess/Fcont) over the wavelength range of 6490-6501Å
Note (1): b = Hα profile shows an inverse P Cygni shape indicating active accretion, despite the small FW 10%. Note (2): The R value of Tonry & Davis (1979AJ.....84.1511T). The 90% confidence interval for vsini is approximately vsini/(1+R).
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Jun-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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