J/AJ/128/805 Low-mass stars in the Cepheus OB2 region (Sicilia-Aguilar+ 2004)
Low-mass stars and accretion at the ages of planet formation in the Cepheus OB2
region.
Sicilia-Aguilar A., Hartmann L.W., Briceno C., Muzerolle J., Calvet N.
<Astron. J., 128, 805-821 (2004)>
=2004AJ....128..805S 2004AJ....128..805S
ADC_Keywords: Spectral types ; Equivalent widths ; Photometry, Cousins ;
Photometry, infrared ; Stars, pre-main sequence
Keywords: planetary systems: protoplanetary disks - stars: pre-main-sequence
Abstract:
We present the first identification of low-mass (spectral types K-M)
stars in the young clusters Tr37 and NGC7160, members of the CepOB2
association. This is part of a program to follow the evolution of
protoplanetary accretion disks through the ages thought to be crucial
to understanding disk dissipation and planet formation (∼3-10Myr).
Combining optical photometry and optical spectroscopy, we have
identified ∼40 members in Tr37 and ∼15 in NGC7160, using several
independent tests for determining the membership (optical colors,
optical variability, Hα emission, and Liλ6707
absorption).
Description:
Our optical photometry observations of Tr37 and NGC7160 were carried
on with the 1.2m telescope at the Fred Lawrence Whipple Observatory
(FLWO), using the 4Shooter CCD array, between 1998 and 2002. Optical
spectra of the most likely cluster members were taken in three
Hydra/3.5m WIYN observing runs in 1999 January-August, 2000 November,
and 2002 November. Additional spectra for the brighter candidates were
observed with FAST/1.5m telescope in several remote runs from 2001 to
2003.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 79 53 Tr 37 spectral data, extinction, and membership
table3.dat 50 25 NGC 7160 spectral data, extinction, and membership
table6.dat 98 53 Tr 37 photometry
table7.dat 98 25 NGC 7160 photometry
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Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- [SHB2004] Name (1)
9- 11 A3 --- ST Spectral type
17- 21 A5 --- STI Spectral interval
25- 28 I4 0.1nm EW(Ha) ? Hα absorption equivalent width
33- 35 F3.1 0.1nm EW(Li) ? Li (6707Å) absorption equivalent width
37- 38 A2 --- f_EW(Li) [? No] Flag on EW(Li) (2)
41- 44 F4.2 mag AV ? Extinction, averaged from E(V-R) and E(V-I)
49- 50 A2 --- Memb [Y PY PN] Membership (3)
57- 79 A23 --- Comm Comments (4)
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Note (1): Table 2: [SHB2004] Cl* Trumpler 37 NN-NNNN in Simbad
Table 3: [SHB2004] Cl* NGC 7160 NN-NNNN in Simbad
Note (2): Flag on EW(Li), defined as follows:
? = probable lithium detection, although signal to noise is not good to
measure EWs
No = no lithium detection
Note (3): The membership is defined as follows:
Y = certain members
PY = probable members
PN = highly probable non-members that need more information to be completely
ruled out
Note (4): Comments use the abbreviations:
Yg = stars showing an apparent younger age in the V vs. V-I diagram
Ue = excess in U band
IRe = near-IR excess from the 2MASS survey
IRAC = objects for which we have detected IR excess from our IRAC/Spitzer
images
CTTS = accreting star (Classical T Tauri Star)
WTTS = nonaccreting star (Weak T Tauri Star)
The type of the star (accreting CTTS, nonaccreting WTTS) is based on
Hα strength, IR excess, and U-band excess as accretion indicators,
so then any star with Hα<10Å, and no other signatures of accretion
is considered WTTS, because Hα EWs may have significant errors because
of the complex background subtraction)
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Byte-by-byte Description of file: table6.dat table7.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- [SHB2004] Name (1)
9- 10 I2 h RAh ? Hour of Right Ascension (J2000.0)
12- 13 I2 min RAm ? Minute of Right Ascension (J2000.0)
15- 19 F5.2 s RAs ? Second of Right Ascension (J2000.0)
24 A1 --- DE- Sign of Declination (J2000.0)
25- 26 I2 deg DEd ? Degree of Declination (J2000.0)
28- 29 I2 arcmin DEm ? Arcminute of Declination (J2000.0)
31- 35 F5.2 arcsec DEs ? Arcsecond of Declination (J2000.0)
41- 46 F6.3 mag Vmag ? V magnitude
49- 53 F5.3 mag V-Rc ? V-R (Cousins) colour index
57- 61 F5.3 mag V-Ic ? V-I (Cousins) colour index
65- 70 F6.3 mag Jmag ? 2MASS J magnitude
73- 78 F6.3 mag Hmag ? 2MASS H magnitude
81- 86 F6.3 mag Ksmag ? 2MASS Ks magnitude
89- 94 F6.3 mag Umag ? U magnitude
97- 98 A2 --- Var Variability (contains the bands where
variations were detected)
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Note (1): Table6: [SHB2004] Cl* Trumpler 37 NN-NNNN in Simbad
Table7: [SHB2004] Cl* NGC 7160 NN-NNNN in Simbad
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History:
From electronic version of the journal
(End) Marianne Brouty [CDS] 31-Mar-2005