J/MNRAS/468/2684 IC1805 YSOs (Panwar+, 2017)
Low-mass young stellar population and star formation history of the
cluster IC 1805 in the W4 H II region.
Panwar N., Samal M.R., Pandey A.K., Jose J., Chen W.P., Ojha D.K.,
Ogura K., Singh H.P., Yadav R.K.
<Mon. Not. R. Astron. Soc., 468, 2684-2698 (2017)>
=2017MNRAS.468.2684P 2017MNRAS.468.2684P (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; YSOs ; Photometry, infrared ; Stars, masses ;
Stars, ages
Keywords: stars: formation - stars: pre-main-sequence - HII regions -
open clusters and associations: individual: IC 1805
Abstract:
W4 is a giant HII region ionized by the OB stars of the cluster
IC 1805. The HII region/cluster complex has been a subject of numerous
investigations as it is an excellent laboratory for studying the
feedback effect of massive stars on the surrounding region. However,
the low-mass stellar content of the cluster IC 1805 remains poorly
studied till now. With the aim to unravel the low-mass stellar
population of the cluster, we present the results of a multiwavelength
study based on deep optical data obtained with the
Canada-France-Hawaii Telescope, infrared data from Two Micron All Sky
Survey and SpitzerSpace Telescope and X-ray data from ChandraSpace
Telescope. The present optical data set is complete enough to detect
stars down to 0.2M☉, which is the deepest optical observation so
far for the cluster. We identified 384 candidate young stellar objects
(YSOs; 101 Class I/II and 283 Class III) within the cluster using
various colour-colour and colour-magnitude diagrams. We inferred the
mean age of the identified YSOs to be ∼2.5Myr and mass in the range
0.3-2.5M☉. The mass function of our YSO sample has a power-law
index of -1.23±0.23, close to the Salpeter value (-1.35), and
consistent with those of other star-forming complexes. We explored the
disc evolution of the cluster members and found that the disc-less
sources are relatively older compared to the disc bearing YSO
candidates. We examined the effect of high-mass stars on the
circumstellar discs and within uncertainties, the influence of massive
stars on the disc fraction seems to be insignificant. We also studied
the spatial correlation of the YSOs with the distribution of gas and
dust of the complex to conclude that IC 1805 would have formed in a
large filamentary cloud.
Description:
With the aim of unravelling the less known low-mass YSO population of
the cluster IC 1805 which is rich in massive OB stars, we studied the
region using optical, IR and X-ray data sets.
The NIR/MIR data from the Spitzerspace telescope using IRAC centred at
3.6, 4.5, 5.8 and 8.0um were obtained from the Spitzer archive. IC
1805 was observed in 2006 September (P.I. S. Wolff, Program ID 20052).
The region was observed at MIPS 24um in 2005 September (P.I. J.S.
Greaves, Program ID 3234).
The pre-processed deep V- and R-band images of the IC 1805 region were
obtained from the CFHT archive.
Our final catalogue includes the YSO candidates identified from
Spitzer IRAC/MIPS, 2MASS and X-ray data sets. In total, we have 297
Class III, eight transition disc and 272 Class I/II candidates in the
direction of the W4 complex. However, there are only 101 Class I/II
and 283 Class III candidates in the cluster (i.e. within ∼9 arcmin).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 120 384 YSOs from 2MASS, and IRAC/MIPS data for the
cluster area
table4.dat 67 370 Magnitudes, age and mass of the YSOs in the
cluster region
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See also:
J/A+A/554/A3 : Vilnius photometry of IC1805 stars (Straizys+, 2013)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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1- 3 I3 --- Id [1/384] Sequential number within the table
6- 14 F9.6 deg RAdeg Right ascension (J2000)
16- 24 F9.6 deg DEdeg Declination (J2000)
26- 30 F5.2 mag Jmag ?=99.99 2MASS J magnitude
32- 36 F5.2 mag e_Jmag ?=99.99 2MASS J magnitude error
38- 42 F5.2 mag Hmag ?=99.99 2MASS H magnitude
44- 48 F5.2 mag e_Hmag ?=99.99 2MASS H magnitude error
50- 54 F5.2 mag Ksmag ?=99.99 2MASS Ks magnitude
56- 60 F5.2 mag e_Ksmag ?=99.99 2MASS Ks magnitude error
62- 66 F5.2 mag [3.6] ?=99.99 IRAC 3.6um magnitude
68- 72 F5.2 mag e_[3.6] ?=99.99 IRAC 3.6um magnitude error
74- 78 F5.2 mag [4.5] ?=99.99 IRAC 4.5um magnitude
80- 84 F5.2 mag e_[4.5] ?=99.99 IRAC 4.5um magnitude error
86- 90 F5.2 mag [5.8] ?=99.99 IRAC 5.8um magnitude
92- 96 F5.2 mag e_[5.8] ?=99.99 IRAC 5.8um magnitude error
98-102 F5.2 mag [8.0] ?=99.99 IRAC 8.0um magnitude
104-108 F5.2 mag e_[8.0] ?=99.99 IRAC 8.0um magnitude error
110-114 F5.2 mag [24] ?=99.99 MIPS 24um magnitude
116-120 F5.2 mag e_[24] ?=99.99 MIPS 24um magnitude error
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Id [1/370] Sequential number within the table
6- 14 F9.6 deg RAdeg Right ascension (J2000)
16- 24 F9.6 deg DEdeg Declination (J2000)
26- 30 F5.2 mag Vmag V magnitude
32- 35 F4.2 mag e_Vmag V magnitude error
37- 41 F5.2 mag Rmag R magnitude
43- 46 F4.2 mag e_Rmag R magnitude error
48 A1 --- l_Age Limit flag on Age
49- 52 F4.2 Myr Age Age
54- 57 F4.2 Myr e_Age ?=9.99 Age error
59- 62 F4.2 Msun Mass Mass
64- 67 F4.2 Msun e_Mass Mass error
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Mar-2020