J/ApJ/767/36 APEX observations of HOPS protostars (Stutz+, 2013)
A Herschel and APEX census of the reddest sources in Orion: searching for the
youngest protostars.
Stutz A.M., Tobin J.J., Stanke T., Megeath S.T., Fischer W.J.,
Robitaille T., Henning T., Ali B., di Francesco J., Furlan E., Hartmann L.,
Osorio M., Wilson T.L., Allen L., Krause O., Manoj P.
<Astrophys. J., 767, 36 (2013)>
=2013ApJ...767...36S 2013ApJ...767...36S
ADC_Keywords: YSOs ; Photometry, infrared ; Photometry, millimetric/submm ;
Molecular clouds
Keywords: ISM: clouds; stars: formation; stars: low-mass; stars: protostars
Abstract:
We perform a census of the reddest, and potentially youngest,
protostars in the Orion molecular clouds using data obtained with the
PACS instrument on board the Herschel Space Observatory and the LABOCA
and SABOCA instruments on APEX as part of the Herschel Orion Protostar
Survey (HOPS). A total of 55 new protostar candidates are detected at
70µm and 160µm that are either too faint (m24>7mag) to be
reliably classified as protostars or undetected in the Spitzer/MIPS
24µm band. We find that the 11 reddest protostar candidates with
logλFλ70/λFλ24>1.65 are free of
contamination and can thus be reliably explained as protostars. The
remaining 44 sources have less extreme 70/24 colors, fainter 70µm
fluxes, and higher levels of contamination. Taking the previously
known sample of Spitzer protostars and the new sample together, we
find 18 sources that have
logλFλ70/λFλ24>1.65; we name these
sources "PACS Bright Red sources," or PBRs. Our analysis reveals that
the PBR sample is composed of Class 0 like sources characterized by
very red spectral energy distributions (SEDs; Tbol<45K) and large
values of sub-millimeter fluxes (Lsmm/Lbol>0.6%). Modified
blackbody fits to the SEDs provide lower limits to the envelope masses
of 0.2-2M☉ and luminosities of 0.7-10L☉. Based on these
properties, and a comparison of the SEDs with radiative transfer
models of protostars, we conclude that the PBRs are most likely
extreme Class 0 objects distinguished by higher than typical envelope
densities and hence, high mass infall rates.
Description:
In this work, we present Herschel scan-map observations of a subset of
the Herschel Orion Protostar Survey (HOPS) fields containing candidate
protostars. In addition, we present a subset of our APEX LABOCA and
SABOCA observations of these fields.
A summary of the HOPS Herschel PACS survey observations is presented
in Tables 1 and 2.
We obtained sub-millimeter (smm) continuum maps using the LABOCA and
SABOCA bolometer arrays on the APEX telescope. LABOCA is a ∼250
bolometer array operating at 870um, with a spatial resolution of ∼19"
at FWHM. SABOCA is a 37 bolometer array operating at 350um, with a
resolution of ∼7.3" FWHM. For both cameras, observations were carried
out between 2009 November and 2012 June, and are still ongoing to
complete our Submillimeter Orion Survey. The observations will be
summarized in more detail by T. Stanke et al. (2013prpl.conf1G004S).
The IRAC and MIPS imaging and photometry presented here are taken from
the 9deg2 survey of the Orion A and B cloud obtained during the
cryogenic Spitzer mission.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 66 71 Summary of HOPS Herschel PACS L1641 observations
table2.dat 66 37 Summary of HOPS Herschel PACS ONC, NGC 2024,
NGC 2068, and L1622 observations
table3.dat 113 55 Herschel protostar candidate coordinates and
photometry
table4.dat 104 18 Spitzer and Herschel photometric properties of
PACS Bright Red sources (PBRs)
table5.dat 48 18 APEX 350 and 870um photometry of PACS Bright Red
sources
table6.dat 100 18 Orion PBRs observed properties: detections,
environment, and previous detections
table8.dat 72 23 Orion PBRs and comparison class 0 sources: observed
properties and modified blackbody fit parameters
refs.dat 116 31 References
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See also:
B/eso : ESO Science Archive Catalog (ESO, 1991-2014)
VI/139 : Herschel Observation Log (Herschel Science Centre, 2013)
J/ApJS/208/28 : Hα survey in the ONC (Szegedi-Elek+, 2013)
J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSO catalog (Megeath+, 2012)
J/AJ/144/31 : Spitzer+2MASS phot. of protostar candidates (Kryukova+, 2012)
J/A+A/547/A49 : Herschel EPoS: high-mass overview (Ragan+, 2012)
J/A+A/538/A137 : Orion B9 dense cores maps (Miettinen+, 2012)
J/ApJ/752/59 : Low-mass population in L1641 (Hsu+, 2012)
J/ApJ/748/14 : ONC population data from WFI observations (Da Rio+, 2012)
J/ApJ/733/50 : MIR phot. monitoring of the ONC (Morales-Calderon+, 2011)
J/ApJ/710/1247 : Dense cores in Gould Belt clouds (Sadavoy+, 2010)
J/A+A/507/1485 : Young (proto)stellar population in L1630 (Mookerjea+ 2009)
J/A+A/504/461 : YSOs in L1630N and L1641 (Fang+, 2009)
J/A+A/496/153 : Molecular hydrogen flows along Ori A cloud (Davis+, 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/179/249 : Low-luminosity embedded protostar population (Dunham+, 2008)
J/ApJS/175/277 : Submillimeter-Continuum SCUBA detections (Di Francesco+, 2008)
J/AJ/136/2413 : Galactic midplane Spitzer red sources (Robitaille+, 2008)
J/AJ/135/966 : Circumstellar disk evolution in NGC 2068/71 (Flaherty+, 2008)
J/ApJ/677/401 : Xray properties of protostars in ONC (Prisinzano+, 2008)
J/MNRAS/374/1413 : SCUBA survey of Orion (Nutter+, 2007)
J/ApJ/671/605 : NGC 2264 and ONC PMS stars in the infrared (Cieza+, 2007)
J/ApJ/669/493 : Spitzer/Chandra YSOs in Serpens cloud core (Winston+, 2007)
J/ApJ/653/383 : SCUBA observations in Orion A South region (Johnstone+, 2006)
J/ApJ/646/297 : Spitzer obs. of pre-main-sequence stars (Rebull+, 2006)
J/AJ/125/1537 : QUIRC Chandra sources in OMC 2/3 (Tsujimoto+, 2003)
J/A+A/392/239 : IR survey of outflows in Orion A (Stanke+, 2002)
J/A+A/372/L41 : NGC 2068/2071 protoclusters (Motte+, 2001)
J/ApJ/559/307 : Sub-mm mapping in Orion B molecular cloud (Johnstone+, 2001)
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- HOPS [0/320] Herschel Orion Protostar Survey (HOPS)
group name
5 I1 h RAh [5] Field center hour of right ascension (J2000)
7- 8 I2 min RAm [33/54] Field center minute of
right ascension (J2000)
10- 15 F6.3 s RAs Field center second of right ascension (J2000)
17 A1 --- DE- Field center sign of declination (J2000)
18 I1 deg DEd Field center degree of declination (J2000)
20- 21 I2 arcmin DEm Field center arcminute of declination (J2000)
23- 27 F5.2 arcsec DEs Field center arcminute of declination (J2000)
29- 36 A8 --- Field Field name (G1)
38- 58 A21 --- ObsId AOR identification numbers
60- 62 I3 --- OD [300/858] Herschel Operational Day
64 I1 arcmin Size1 [5/8] Map Size
65 A1 --- --- [x]
66 I1 arcmin Size2 [5/8] Map Size
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Source [3/313006] Source number
8 A1 --- f_Source [b] Source free of contamination (in bold) (1)
10- 12 I3 --- HOPS [0/313]? Group name
14- 15 I2 h RAh PACS 70um source hour of right ascension (J2000)
17- 18 I2 min RAm PACS 70um source minute of right ascension (J2000)
20- 24 F5.2 s RAs PACS 70um source second of right ascension (J2000)
26 A1 --- DE- PACS 70um source sign of declination (J2000)
27- 28 I2 deg DEd PACS 70um source degree of declination (J2000)
30- 31 I2 arcmin DEm PACS 70um source arcminute of declination (J2000)
33- 37 F5.2 arcsec DEs PACS 70um source arcsecond of declination (J2000)
39- 46 A8 --- Field Field name (G1)
48- 49 A2 --- l_F24 [≤] Limit flag on 24um
51- 56 F6.2 mJy F24 [1.1/124] Spitzer/MIPS 24um flux density
58- 60 F3.1 mJy e_F24 [0.2/0.5]? F24 uncertainty
62- 68 F7.2 mJy F70 [9.7/4571] Herschel/PACS 70um flux density
70- 74 F5.1 mJy e_F70 [0.5/229] F70 uncertainty
76- 80 I5 mJy F160 [137/51254] Herschel/PACS 160um flux density
82- 85 I4 mJy e_F160 [10/7688] F160 uncertainty
87 I1 --- q_Source [1/5] Protostar reliability flag, 1=best (2)
89- 91 A3 --- 870? [Yes ] 870um detection? (3)
93- 97 F5.1 K Tbol [23/336.1] Bolometric temperature
99-103 F5.2 K e_Tbol [0.2/15] Tbol uncertainty
105-108 F4.2 Lsun Lbol [0.02/6.3] Bolometric luminosity
110-113 F4.2 Lsun e_Lbol [0.01/0.7] Lbol uncertainty
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Note (1): Sources in boldface in the printed table, having
log(λFλ(70)/λFλ(24))>1.65
Note (2): Flag as follows:
1 = the source is a reliable protostar
2 = the source is considered less likely to be a protostar
3 = the source is flagged as extragalactic contamination
4 = the SED shape is with IRAC photospheric emission
5 = the source has no IRAC coverage
Note (3): This column indicates if the source has a strong 870um detection;
sources with no data are either assigned upper limits or have no coverage.
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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- 7 A7 --- Source Source number
9- 11 I3 --- HOPS [0/303]? Group name
13- 14 I2 h RAh PACS 70um source hour of right ascension (J2000)
16- 17 I2 min RAm PACS 70um source minute of RA (J2000)
19- 22 F4.1 s RAs PACS 70um source second of RA (J2000)
24 A1 --- DE- PACS 70um source sign of declination (J2000)
25- 26 I2 deg DEd PACS 70um source degree of declination (J2000)
28- 29 I2 arcmin DEm PACS 70um source arcminute of DEC (J2000)
31- 35 F5.2 arcsec DEs PACS 70um source arcsecond of DEC (J2000)
37- 44 A8 --- Field Field name
46- 47 A2 --- l_F24 [≤] Limit flag on F24
49- 54 F6.2 mJy F24 [1/422] Spitzer/MIPS 24um flux density
56- 59 F4.1 mJy e_F24 [0.2/42]? F24 uncertainty
61- 65 I5 mJy F70 [302/60681] Herschel/PACS 70um flux density
67- 70 I4 mJy e_F70 F70 uncertainty
72- 77 I6 mJy F100 [1977/104322] Herschel/PACS 100um flux density
79- 83 I5 mJy e_F100 F100 uncertainty
85- 90 I6 mJy F160 [5108/123207] Herschel/PACS 160um flux density
92- 96 I5 mJy e_F160 F160 uncertainty
98- 99 A2 --- l_log70/24 [≥] Limit flag on log70/24
101-104 F4.2 [-] log70/24 [1.6/2.7] Log of 70um to 24um flux ratio;
logλFλ70/λFλ24
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Source Source name
9- 13 F5.2 Jy/beam F350b [2.1/14]? 350um flux density in Jy/beam
15 A1 --- f_F350b [c] Point from literature (1)
17- 21 F5.2 Jy F350 [3.1/26]? APEX 350um aperture flux density (2)
23- 27 F5.2 Jy F350c [2.2/19]? 350um corrected flux density (3)
29- 30 A2 --- l_F870b [≤] Limit flag on F870b
32- 34 F3.1 Jy/beam F870b [0.5/3] 870um flux density in Jy/beam
36- 37 A2 --- l_F870 [≤] Limit flag on F870
39- 41 F3.1 Jy F870 [0.9/5] APEX 870um aperture flux density (2)
43- 44 A2 --- l_F870c [≤] Limit flag on F870c
46- 48 F3.1 Jy F870c [0.5/4] 870um corrected flux density (3)
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Note (1):
c = 350um point from Miettinen et al. 2012 (J/A+A/538/A137).
Note (2): Source flux measured in an aperture with radius equal to 1xFWHM,
where the FWHM=7.34" and 19.0" at 350 and 870um, respectively.
Note (3): Source flux measured in the same aperture as in "Note (2)" but
with local sky subtraction over radii equal to {1.5,2.0}xFWHM.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Source Source name
9- 10 I2 h RAh PACS 70um source hour of right ascension (J2000)
12- 13 I2 min RAm PACS 70um source minute of RA (J2000)
15- 18 F4.1 s RAs PACS 70um source second of RA (J2000)
20 A1 --- DE- PACS 70um source sign of declination (J2000)
21- 22 I2 deg DEd PACS 70um source degree of declination (J2000)
24- 25 I2 arcmin DEm PACS 70um source arcminute of DEC (J2000)
27- 30 F4.1 arcsec DEs PACS 70um source arcsecond of DEC (J2000)
32- 34 A3 --- 4.5? [Yes No] 4.5um detection?
36- 38 A3 --- Inc? [Yes ] High inclination? (4)
40- 42 A3 --- 24? [Yes/No] 24um detection?
44- 47 A4 --- Note Note(s) on Source (5)
49-100 A52 --- Ref Selected references (see refs.dat file)
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Note (4): Sources with indications of an observed high inclination orientation
from the 4.5um images.
Note (5): Note as follows:
ns = nearby source and indicates that we find a source close (≲30") to the
target;
f = filament and indicates that a significant level of elongation or extended
emission is seen in the 870um data;
i = isolated and indicates that no nearby source is observed;
c = crowded, indicating that the source resides in a region possibly with
multiple sources, extended emission, or both and whose photometry may be
affected by source blending;
b = binary, sources that may have an unresolved secondary source and
therefore blended photometry.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Source Source name
13 A1 --- n_Source Additional note on Source (1)
15- 18 F4.1 K Tbol [28/64] Bolometric temperature
20- 22 F3.1 K e_Tbol [0/3.3] Tbol uncertainty
24- 28 F5.2 Lsun Lbol [0.2/31] Bolometric luminosity
30- 33 F4.2 Lsun e_Lbol [0/2.21] Lbol uncertainty
35- 38 F4.1 % Lsmm/b [0.6/11] Submillimetric to
bolometric luminosity ratio (2)
40- 43 F4.1 K Tmbb [12.7/27.2] Modified blackbody temperature (3)
45- 47 F3.1 K e_Tmbb [0.3/1.1] Tmbb uncertainty (3)
49- 53 F5.2 Lsun Lmbb [0.1/19.5] Modified blackbody luminosity (3)
55- 58 F4.2 Lsun e_Lmbb [0.01/1.3] Lmbb uncertainty (3)
60- 63 F4.2 Msun Mmbb [0.1/2.2] Modified blackbody mass (3) (4)
65- 68 F4.2 Msun e_Mmbb [0.02/0.6] Mmbb uncertainty (3) (4)
70- 72 I3 um lam.p [88/199] peak wavelength (λpeak)
of modified blackbody (3)
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Note (1): Flag as follows:
d = The values of Tbol and Lbol for these sources should be considered
upper limits because we include the 24um upper limits in our analysis for
these sources.
e = Additional well-studied isolated Class 0 sources from Launhardt et al.
(2013A&A...551A..98L 2013A&A...551A..98L) and Stutz et al. (2010A&A...518L..87S 2010A&A...518L..87S) are shown for
comparison; the distances to these sources lie between 100pc and 250pc.
f = SED from J. Green and DIGIT team (2012, private communication) and
J. Green et al. (2013ApJ...770..123G 2013ApJ...770..123G).
Note (2): Our Lsmm/Lbol may be underestimated as the Lsmm values are
measured from the modified blackbody fits to the SEDs (see the text).
Note (3): Best-fit modified blackbody parameters; the parameters shown here
are derived from fitting the λ≥70um SED points. Excluding the
70um point and fitting only the λ≥100um points systematically
increases the derived masses by 20% on average, decreases the temperature
by 5% on average, and decreases the luminosity by 7% on average.
Note (4): The masses derived here will increase by a factor of ∼4 if we
assume an ISM-type dust model (Draine & Lee 1984ApJ...285...89D 1984ApJ...285...89D).
Furthermore, we assume a gas-to-dust ratio of 110 (see the text).
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Ref Reference code
6- 24 A19 --- BibCode Bibcode
26- 47 A22 --- Aut Author's name(s)
49-116 A68 --- Comm Comment
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Global note:
Note (G1): The fields are:
ONC = field containing the extended Orion Nebula region,
the NGC 1977 region, and OMC2/3;
NGC 2024 = field containing the NGC 2024 HII region
and the NGC 2023 reflection nebula.
NGC 2068 = field containing the NGC 2068 and NGC 2071 reflection
nebulae as well as LBS23 region.
L1622 = LDN 1622 molecular cloud
L1641 = LDN 1641 molecular cloud
kappaOri = star κ Ori (HIP 27366)
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 18-Nov-2014