J/AJ/150/40 The Spitzer c2d survey of clouds. XII. Perseus (Young+, 2015)
The Spitzer c2d survey of large, nearby, interstellar clouds.
XII. The Perseus YSO population as observed with IRAC and MIPS.
Young K.E., Young C.H., Lai S.-P., Dunham M.M., Evans II N.J.
<Astron. J., 150, 40 (2015)>
=2015AJ....150...40Y 2015AJ....150...40Y
ADC_Keywords: Surveys ; Molecular clouds ; YSOs ; Interstellar medium ;
Photometry, infrared ; Cross identifications
Keywords: dust, extinction - infrared: stars -
ISM: individual objects (IC 348, NGC 1333 Perseus) - stars: formation
Abstract:
The Spitzer Space Telescope mapped the Perseus molecular cloud complex
with the Infrared Array Camera (IRAC) and the Multi-Band Imaging
Photometer for Spitzer (MIPS) as part of the c2d Spitzer Legacy
project. This paper combines the observations from both instruments
giving an overview of low-mass star formation across Perseus from 3.6
to 70µm. We provide an updated list of young stellar objects (YSOs)
with new classifications and source fluxes from previous works,
identifying 369 YSOs in Perseus with the Spitzer data set. By
synthesizing the IRAC and MIPS maps of Perseus and building on the
work of previous papers in this series, we present a current census of
star formation across the cloud and within smaller regions.
Sixty-seven percent of the YSOs are associated with the young clusters
NGC 1333 and IC 348. The majority of the star formation activity in
Perseus occurs in the regions around the clusters to the eastern and
western ends of the cloud complex. The middle of the cloud is nearly
empty of YSOs despite containing regions of high visual extinction.
The western half of Perseus contains three-quarters of the total
number of embedded YSOs (Class 0+I and Flat spectral energy
distribution sources) in the cloud and nearly as many embedded YSOs as
Class II and III sources. Class II and III objects greatly outnumber
Class 0+I objects in eastern Perseus and IC 348. These results are
consistent with previous age estimates for the clusters. Across the
cloud, 56% of YSOs and 91% of the Class 0+I and Flat sources are in
areas where Av≥5mag, indicating a possible extinction threshold for
star formation.
Description:
We present a study of the complete Infrared Array Camera (IRAC) and
Multi-band Imaging Photometer for Spitzer (MIPS) c2d (c2d="From
Molecular Cores to Planet Forming Disks") maps of the Perseus
molecular cloud. Our work synthesizes the data sets first presented by
Jorgensen et al. (2006ApJ...645.1246J 2006ApJ...645.1246J; Paper III) and Rebull et al.
(2007ApJS..171..447R 2007ApJS..171..447R; Paper VI) putting the full Spitzer observations
in the context of more recent work on Perseus. This is the twelfth
paper in a series presenting original Spitzer data of the five large
molecular clouds mapped by the c2d team.
The Perseus molecular cloud was mapped with two of the Spitzer Space
Telescope's instruments, IRAC and MIPS. The Spitzer maps cover 3.86
square degrees in the IRAC observation wavelengths of 3.6, 4.5, 5.8,
and 8.0µm and approximately 10.5 square degrees with MIPS at 24,
70, and 160µm. However, due to the nature of the detector, the
160µm maps are not complete and provide only limited photometry for
a portion of the Young Stellar Objects (YSOs).
The c2d catalogs for Perseus as well as the other molecular clouds and
cores included in the survey are available online through the
NASA/IPAC Infrared Science Archive (IRSA:c2d 2007,
http://irsa.ipac.caltech.edu/data/SPITZER/C2D/).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 124 143 Young Stellar Objects (YSOs) in the IC 348 region
table2.dat 124 104 Young Stellar Objects (YSOs) in the NGC 1333 region
table3.dat 124 122 Young Stellar Objects (YSOs) in the remaining cloud
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See also:
II/332 : c2d Spitzer final data release (DR4) (Evans+, 2003)
J/AJ/150/17 : A catalog of point sources toward NGC 1333 (Rebull, 2015)
J/ApJS/205/5 : YSO candidates in nearby molecular clouds (Hsieh+, 2013)
J/ApJ/714/778 : YSOs in the Serpens Molecular Cloud (Oliveira+, 2010)
J/ApJ/692/973 : Protostars in Perseus, Serpens and Ophiuchus (Enoch+, 2009)
J/ApJ/691/672 : Spectrocopy of YSOs in Serp. molecular cloud (Oliveira+ 2009)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJS/177/551 : Spitzer c2d survey of Lupus dark clouds (Merin+, 2008)
J/ApJ/684/1240 : Prestellar cores in Pers, Serp and Ophiuchus (Enoch+, 2008)
J/ApJ/676/427 : MIPS and IRAC data on ChaII PMS stars (Alcala+, 2008)
J/ApJ/674/336 : Spitzer observations of NGC 1333 (Gutermuth+, 2008)
J/ApJ/663/1149 : Spitzer survey of Serpens YSO population (Harvey+, 2007)
J/AJ/131/1574 : Infrared photometry of IC348 members (Lada+, 2006)
J/ApJ/646/1009 : Structures of dust in Perseus molecular cloud (Kirk+, 2006)
J/ApJ/638/293 : 1.1mm sources in the Perseus Molecular Cloud (Enoch+, 2006)
J/A+A/440/151 : Observations at 850um in Perseus clusters (Hatchell+, 2005)
Byte-by-byte Description of file: table[123].dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- E09 [121/505] Source index number from Evans et al.
2009 (J/ApJS/181/321)
5- 23 A19 --- SSTc2d Spitzer source name (JHHMMSS.ss+DDMMSS.s) (1)
25- 29 F5.2 --- alpha [-2.48/3.4] Spectral index α (2)
31- 34 A4 --- Class Classification according the spectral index
α (0+I, II, III, or Flat) (3)
36- 42 F7.2 mJy F3.6 [0.04/1300]? Spitzer/IRAC 3.6µm band flux
density (4)
44- 49 F6.2 mJy e_F3.6 [0/110]? Uncertainty in F3.6
51- 57 F7.2 mJy F4.5 [0.03/2400]? Spitzer/IRAC 4.5µm band flux
density (4)
59- 64 F6.2 mJy e_F4.5 [0/230]? Uncertainty in F4.5
66- 72 F7.2 mJy F5.8 [0.13/3900]? Spitzer/IRAC 5.8µm band flux
density (4)
74- 79 F6.2 mJy e_F5.8 [0.01/420]? Uncertainty in F5.8
81- 87 F7.2 mJy F8.0 [0.21/7500]? Spitzer/IRAC 8.0µm band flux
density (4)
89- 94 F6.2 mJy e_F8.0 [0.04/430]? Uncertainty in F8.0
96-101 F6.1 mJy F24 [1.1/7900]? Spitzer/MIPS 24µm band flux
density (4)
103-109 F7.2 mJy e_F24 [0.11/1400]? Uncertainty in F24
111-116 I6 mJy F70 [40/140000]? Spitzer/MIPS 70µm band flux
density (4)
118-124 F7.1 mJy e_F70 [1/15000]? Uncertainty in F70
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Note (1): SSTc2d = "From Molecular Cores to Planet Forming Disks" (c2d)/Spitzer
Space Telescope (SST).
Note (2): The spectral index α is defined by a least squares fit to the
photometry of the source between 2 and 24µm according to Equation (1)
in Evans et al. 2009 (J/ApJS/181/321; the near-infrared flux data are
from 2MASS):
α = dlog(λS(λ))/dlog(λ)
Note (3): The YSOs were placed in the classes defined in Greene et al.
(1994ApJ...434..614G 1994ApJ...434..614G) as follows:
Flat = Flat-spectrum source (-0.3≤α<0.3);
0+I = α≥0.3 is a Class I source. Because Greene et al.
(1994ApJ...434..614G 1994ApJ...434..614G) do not distinguish between Class 0 and Class I
sources and the classes cannot be separated based on spectral index,
we classify all sources with α≥0.3 as Class 0+I.
II = Class II YSO (-1.6≤α< -0.3);
III = α< -1.6. Greene et al. (1994ApJ...434..614G 1994ApJ...434..614G) classification
scheme does not put a lower limit on α for Class III sources
and therefore includes YSOs with spectral energy distributions that
resemble bare stellar photospheres. As noted by Gutermuth et al.
2009 (J/ApJS/184/18), Spitzer data alone cannot identify
diskless Class III sources with no infrared excess. Therefore, our
Class III census represents a lower limit for Perseus.
Note (4): The Spitzer Space Telescope mapped the Perseus molecular cloud complex
with two instruments as part of the c2d Spitzer Legacy project:
IRAC = Infrared Array Camera;
MIPS = Multi-band Imaging Photometer for Spitzer.
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History:
From electronic version of the journal
References:
Young et al., Paper I 2005ApJ...628..283Y 2005ApJ...628..283Y
Harvey et al., Paper II 2006ApJ...644..307H 2006ApJ...644..307H
Jorgensen et al., Paper III 2006ApJ...645.1246J 2006ApJ...645.1246J
Chapman et al., Paper IV 2007ApJ...667..288C 2007ApJ...667..288C
Porras et al., Paper V 2007ApJ...656..493P 2007ApJ...656..493P
Rebull et al., Paper VI 2007ApJS..171..447R 2007ApJS..171..447R
Padgett et al., Paper VII 2008ApJ...672.1013P 2008ApJ...672.1013P
Harvey et al., Paper VIII 2007ApJ...663.1139H 2007ApJ...663.1139H
Harvey et al., Paper IX 2007ApJ...663.1149H 2007ApJ...663.1149H, Cat. J/ApJ/663/1149
Alcala et al., Paper X 2008ApJ...676..427A 2008ApJ...676..427A, Cat. J/ApJ/676/427
Merin et al., Paper XI 2008ApJS..177..551M 2008ApJS..177..551M, Cat. J/ApJS/177/551
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 01-Oct-2015