J/MNRAS/435/3058 VIc photometry of IR-excess stars in NGC6611 (De Marchi+ 2013)
Pre-main-sequence stars older than 8Myr in the Eagle nebula.
De Marchi G., Panagia N., Guarcello M.G., Bonito R.
<Mon. Not. R. Astron. Soc., 435, 3058-3070 (2013)>
=2013MNRAS.435.3058D 2013MNRAS.435.3058D
ADC_Keywords: Clusters, open; Photometry, UBVRI
Keywords: accretion, accretion discs - scattering - protoplanetary discs -
circumstellar matter -
Hertzsprung-Russell and colour-magnitude diagrams -
stars: pre-main-sequence
Abstract:
Attention is given to a population of 110 stars in the NGC 6611
cluster of the Eagle nebula that have prominent near-infrared excess
and optical colours typical of pre-main-sequence (PMS) stars older
than 8Myr. At least half of those for which spectroscopy exists have a
Hα emission line profile revealing active accretion. In
principle, the V-I colours of all these stars would be consistent with
those of young PMS objects (<1Myr) whose radiation is heavily obscured
by a circumstellar disc seen at high inclination and in small part
scattered towards the observer by the back side of the disc. However,
using theoretical models it is shown here that objects of this type
can only account for a few percent of this population. In fact, the
spatial distribution of these objects, their X-ray luminosities, their
optical brightness, their positions in the colour-magnitude diagram
and the weak Li absorption lines of the stars studied
spectroscopically suggest that most of them are at least eight times
older than the ∼1Myr-old PMS stars already known in this cluster and
could be as old as ∼30Myr. This is the largest homogeneous sample to
date of Galactic PMS stars considerably older than 8Myr that are still
actively accreting from a circumstellar disc and it allows us to set a
lower limit of 7 percent to the disc frequency at ∼16Myr in NGC 6611.
These values imply a characteristic exponential lifetime of ∼6Myr for
disc dissipation.
Description:
The data analysed in this work were extracted from the multiband
photometric catalogue of NGC 6611 and of the surrounding M 16 cloud
compiled by Guarcello et al. (2010, Cat. J/A+A/521/A61).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 52 624 Photometric catalogue of stars with NIR excess
in NGC 6611
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See also:
J/A+AS/121/223 : Multiphotometry of NGC6611 (de Winter+ 1997)
J/A+AS/134/525 : NGC6611 compiled catalog (Belikov+ 1999)
J/A+AS/144/195 : UBVRI polarimetric observations in NGC6611 (Orsatti+, 2000)
J/A+A/462/245 : BVI photometry in NGC 6611 (Guarcello+, 2007)
J/A+A/496/453 : Photometry of candidate members of NGC6611 (Guarcello+ 2009)
J/AJ/132/1783 : UBVRI polarimetry of 25 stars in NGC6611 (Orsatti+, 2006)
J/MNRAS/392/1034 : IZJHKL' photometry of NGC6611 (Oliveira+, 2009)
J/MNRAS/400/1479 : RV catalogue of O-type stars in NGC6611 (Sana+, 2009)
J/A+A/521/A18 : Blue stars with disk photometry in NGC6611 (Guarcello+ 2010)
J/A+A/521/A61 : Stars associated to Eagle Nebula (NGC6611) (Guarcello+ 2010)
J/ApJ/753/117 : X-ray catalog of Eagle Nebula (Guarcello+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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2- 4 I3 --- ID [1/624] Stellar ID in NGC6611 (M16)
6- 15 F10.6 deg RAdeg Right ascension in decimal degrees (J2000)
17- 26 F10.6 deg DEdeg Declination in decimal degrees (J2000)
28- 32 F5.2 mag Vmag V magnitude (1)
35- 38 F4.2 mag e_Vmag V magnitude error
40- 44 F5.2 mag Icmag Ic magnitude (1)
47- 50 F4.2 mag e_Icmag Ic magnitude error
52 A1 --- X [O/Y/N] X-ray detection flag: Y=yes, N=no,
N=not covered by X-ray observations
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Note (1): observations made with the Wield Field Camera (WFI) mounted
on the 2.2m telescope of the European Southern Observatory (ESO)
in La Silla (Chile), in July 2000.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 11-Oct-2014