J/ApJ/726/19 Intermediate-mass stars in IC 1805 (Wolff+, 2011)
The evolution of circumstellar disks surrounding intermediate-mass stars:
IC 1805.
Wolff S.C., Strom S.E., Rebull L.M.
<Astrophys. J., 726, 19 (2011)>
=2011ApJ...726...19W 2011ApJ...726...19W
ADC_Keywords: Clusters, open ; Spectral types ; Equivalent widths ;
Photometry, infrared ; Photometry, UBV ; Reddening ; YSOs
Keywords: circumstellar matter - planetary systems - stars: early-type -
stars: formation - stars: pre-main sequence
Abstract:
We report the results of a study of the intermediate- and high-mass
stars in the young, rich star-forming complex IC 1805, based on a
combination of optical, near-infrared, and mid-infrared photometry,
and classification spectra. These data provide the basis for
characterizing the masses and ages for stars more massive than
∼2M☉ and enable a study of the frequency and character of
circumstellar disks associated with intermediate- and high-mass stars.
Optically thick accretion disks among stars with masses 2<M/M☉<4
are rare (∼2% of members) and absent among more massive stars. A
larger fraction (∼10%) of stars with masses 2<M/M☉<4 appear to
be surrounded by disks that have evolved from the initial optically
thick accretion phase. We identify four classes of such disks. These
classes are based on spectral energy distributions (SEDs) of excess
emission above photospheric levels: disks that are (1) optically thin
based on the magnitude of the observed excess emission from 2 to 24um,
(2) optically thin in their inner regions (r<20AU) and optically thick
in their outer regions, (3) exhibit empty inner regions (r<10AU) and
optically thin emission in their outer regions, and (4) exhibit empty
inner regions and optically thick outer regions. We discuss, and
assess the merits and liabilities of, proposed explanations for disks
exhibiting these SED types and suggest additional observations that
would test these proposals.
Description:
The UBV photometric study by Massey et al. (1995, Cat. J/ApJ/454/151)
provides a list of 1023 optically selected candidate members of IC 1805
down to a mass of about 2M☉. We observed this region with
Spitzer using the Infrared Array Camera (IRAC; program, 20052, AORKEY
13846016) and the Multiband Imaging Photometer for Spitzer (MIPS;
programs 20052 and 3234 (PI J. Greaves)).
To assist with the determination of reddening, we obtained spectra of
a sample of 229 of the 802 candidates. The observations were obtained
with the Hydra multi-object fiber spectrograph at the WIYN telescope
on 2007 October 30 to November 2. The spectra covered the wavelength
range 3600-5300Å at a resolution of 1.3Å/pixel and a typical
signal-to-noise ratio of 30-100.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 150 974 Spitzer measurements for sample of previously
identified IC 1805 members
table3.dat 47 229 Spectral types and likely members of IC 1805
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
V/96 : Catalogue of open cluster parameters from UBV-data. (Loktin+, 1994)
J/ApJ/726/18 : Disk evolution in W5: stars at 2-5Myr (Koenig+, 2011)
J/AJ/140/462 : Intermediate-mass star-forming regions (Arvidsson+, 2010)
J/MNRAS/407/2109 : Kinematic study of open clusters (Vande Putte+, 2010)
J/ApJS/184/172 : High- and intermediate-mass YSOs in the LMC (Gruendl+, 2009)
J/ApJS/179/451 : IR excesses for protoplanetary disks (Kenyon+, 2008)
J/AJ/133/1092 : vsini of B0-B3 stars in 7 young clusters (Wolff+, 2007)
J/MNRAS/382/1073 : M/L relation of intermediate-mass stars (Malkov+, 2007)
J/A+A/464/581 : Sco OB2 intermediate-mass stars (Kouwenhoven+, 2007)
J/ApJ/653/675 : Spitzer 24µm photometry of A dwarfs (Su+, 2006)
J/ApJ/648/591 : Stellar rotation in young clusters. II. (Huang+, 2006)
J/A+A/432/861 : Yields of low and intermediate mass stars (Gavilan+, 2005)
J/ApJ/454/151 : OB Associations of the Northern Milky Way (Massey+ 1995)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq Optical index number from Massey et al. (1995,
Cat. J/ApJ/454/151; "recno" in VizieR;
<[MJD95] JHHMMSS.ss+DDMMSS.s> in Simbad)
6- 14 F9.6 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 24 F9.6 deg DEdeg Declination in decimal degrees (J2000)
26- 41 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs; J2000)
43- 47 F5.2 mag Umag The U band magnitude from MJD95
49- 53 F5.2 mag Bmag The B band magnitude from MJD95
55- 59 F5.2 mag Vmag The V band magnitude from MJD95
61- 65 F5.2 mag Jmag ? 2MASS J band magnitude
67- 70 F4.2 mag e_Jmag ? Uncertainty in Jmag
72- 76 F5.2 mag Hmag ? 2MASS H band magnitude
78- 81 F4.2 mag e_Hmag ? Uncertainty in Hmag
83- 87 F5.2 mag Ksmag ? 2MASS Ks band magnitude
89- 92 F4.2 mag e_Ksmag ? Uncertainty in Ksmag
94 A1 --- l_[3.6] Limit flag on [3.6]
95- 99 F5.2 mag [3.6] ? Spitzer/IRAC 3.6 micron band magnitude
101-104 F4.2 mag e_[3.6] ? Uncertainty in [3.6]
106 A1 --- l_[4.5] Limit flag on [4.5]
107-111 F5.2 mag [4.5] ? Spitzer/IRAC 4.5 micron band magnitude
113-116 F4.2 mag e_[4.5] ? Uncertainty in [4.5]
118-122 F5.2 mag [5.8] ? Spitzer/IRAC 5.8 micron band magnitude
124-127 F4.2 mag e_[5.8] ? Uncertainty in [5.8]
129-133 F5.2 mag [8.0] ? Spitzer/IRAC 8 micron band magnitude
135-138 F4.2 mag e_[8.0] ? Uncertainty in [8.0]
140 A1 --- l_[24] Limit flag on [24]
141-145 F5.2 mag [24] ? Spitzer/MIPS 24 micron band magnitude
147-150 F4.2 mag e_[24] ? Uncertainty in [24]
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Optical index number from Massey et al. (1995,
Cat. J/ApJ/454/151)
4 A1 --- f_Seq [*] IR excess in Seq
6- 7 A2 --- SpT MK spectral type from this paper
9- 12 F4.2 0.1nm EW ? Equivalent width 4430Å interstellar feature
13- 14 A2 --- f_EW Uncertainty flag on EQW
16- 19 F4.2 mag E(B-V)Q ? E(B-V) from Q method (for stars with
Q=(U-B)-0.72x(B-V)←0.4, following Massey et
al., 1995ApJ...438..188M 1995ApJ...438..188M)
21- 24 F4.2 mag E(B-V)S ? E(B-V) from spectral type
26- 29 F4.2 mag E(B-V) Adopted E(B-V)
31- 35 F5.2 mag Bmag0 Dereddened B band magnitude
37- 41 F5.2 mag Vmag0 Dereddened V band magnitude
43- 47 F5.2 mag (B-V)0 Dereddened (B-V) color index
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Aug-2012