J/ApJ/944/49 ACA 870um continuum survey of 300 HOPS sources (Federman+, 2023)
300: an ACA 870um continuum survey of Orion protostars and their evolution.
Federman S., Megeath S.T., Tobin J.J., Sheehan P.D., Pokhrel R., Habel N.,
Stutz A.M., Fischer W.J., Hartmann L., Stanke T., Narang M., Osorio M.,
Atnagulov P., Rahatgaonkar R.
<Astrophys. J., 944, 49 (2023)>
=2023ApJ...944...49F 2023ApJ...944...49F
ADC_Keywords: Stars, pre-main sequence; YSOs; Millimetric/submm sources;
Interferometry; Carbon monoxide
Keywords: Protostars ; Young stellar objects ; Star formation
Abstract:
We present an 870µm continuum survey of 300 protostars from the
Herschel Orion Protostar Survey using the Atacama Compact Array (ACA).
These data measure protostellar flux densities on envelope scales
≤8000au (20") and resolve the structure of envelopes with 1600au (4")
resolution, a factor of 3-5 improvement in angular resolution over
existing single-dish 870µm observations. We compare the ACA
observations to Atacama Large Millimeter/submillimeter Array 12m array
observations at 870µm with ∼0.1" (40au) resolution. Using the 12m
data to measure the fluxes from disks and the ACA data within 2500au
to measure the combined disk plus envelope fluxes, we calculate the
12m/ACA 870µm flux ratios. Our sample shows a clear evolution in
this ratio. Class 0 protostars are mostly envelope-dominated with
ratios <0.5. In contrast, Flat Spectrum protostars are primarily
disk-dominated with ratios near 1, although with a number of face-on
protostars dominated by their envelopes. Class I protostars span the
range from envelope to disk-dominated. The increase in ratio is
accompanied by a decrease in the envelope fluxes and estimated mass
infall rates. We estimate that 80% of the mass is accreted during the
envelope-dominated phase. We find that the 12m/ACA flux ratio is an
evolutionary indicator that largely avoids the inclination and
foreground extinction dependence of spectral energy distribution-based
indicators.
Description:
The observations were conducted as part of project 2018.1.01284.S
using band 7 of the Atacama Compact Array (ACA). The Herschel Orion
Protostar Survey (HOPS; Furlan+ 2016, J/ApJS/224/5) sources were
observed between 2018 October and 2019 March, with an angular
resolution of ∼4", which corresponds to a size of roughly 1600au at
the average distance of the HOPS sample (400pc).
The configuration included two 2.0GHz bandwidth continuum windows
centered on 332.971 and 343.971GHz. The remaining two bands covered
13CO (J=3->2) and 12CO (J=3->2), centered on 330.559 and
345.765GHz with 0.062 and 0.25GHz band-widths, respectively.
For the 12m data, we use the results of the Very Large Array
(VLA)/Atacama Large Millimeter/submillimeter Array (ALMA) Nascent Disk
and Multiplicity survey in Orion (VANDAM; Tobin+ 2020, J/ApJ/890/130).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 78 300 Source properties
table2.dat 100 300 Analysis-derived properties
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See also:
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/ApJ/692/973 : Protostars in Perseus, Serpens and Ophiuchus (Enoch+, 2009)
J/AJ/144/31 : Spitzer+2MASS phot. of protostar candidates (Kryukova+, 2012)
J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSO catalog (Megeath+, 2012)
J/ApJ/767/36 : APEX observations of HOPS protostars (Stutz+, 2013)
J/AJ/148/11 : Infrared photometry in Cygnus-X (Kryukova+, 2014)
J/ApJS/224/5 : Herschel Orion Protostar Survey (HOPS): SEDs (Furlan+, 2016)
J/ApJ/831/125 : ALMA 887um obs. of ChaI star-forming region (Pascucci+, 2016)
J/AJ/156/84 : APOGEE-2 survey of Orion Complex. II. (Kounkel+, 2018)
J/ApJ/890/130 : VANDAM survey of Orion protostars. II. (Tobin+, 2020)
J/ApJ/911/153 : HST 1.60 & 2.05um images of protostars in Orion (Habel+, 2021)
J/ApJS/256/30 : ALMA 1.33mm images of 10 FU Orionis-type stars (Kospal+, 2021)
J/ApJ/920/132 : NEOWISE 6.5yr variability in YSOs (Park+, 2021)
J/ApJ/929/76 : VANDAM survey of Orion protostars. VI. Disks (Sheehan+, 2022)
J/A+A/663/A98 : Young stars in star forming regions (Testi+, 2022)
J/ApJ/925/39 : The VANDAM survey of Orion protostars. V. Mult. (Tobin+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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2- 4 I3 --- HOPS [1/409] HOPS identifier (1)
6- 12 F7.4 deg RAdeg [83.37/88.74] Right ascension (J2000) (1)
14- 20 F7.4 deg DEdeg [-8.84/1.9] Declination (J2000) (1)
22- 26 F5.1 pc Dist [351/441.1] Distance
from Tobin+ 2020, J/ApJ/890/130
28- 31 A4 --- Class SED class (2)
33- 39 F7.2 Lsun Lbol [0.02/1478] Bolometric luminosity (1)
41- 45 F5.1 K Tbol [23/954] Bolometric temperature (1)
47- 49 F3.1 arcsec amaj [4.5/6] Beam, semi-major axis
51- 53 F3.1 arcsec bmin [2.5/3] Beam, semi-minor axis
55- 67 A13 --- HST HST-based morphology (3)
69- 78 A10 --- ACA ACA-based morphology (4)
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Note (1): Identifiers, positions, Classes, Lbol and Tbol from
Furlan+ 2016, J/ApJS/224/5
Note (2): Classes from Furlan+ 2016, J/ApJS/224/5, as follows:
0 = Class 0 (89 occurrences)
I = Class I (114 occurrences)
Flat = Flat Spectrum (89 occurrences)
II = Class II (8 occurrences)
Note (3): HST-based NIR morphologies described in Habel+ 2021, J/ApJ/911/153
and in Section 5.3 in the text.
Note (4): ACA-based sub-mm morphologies described in Section 3.2 in the text.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- HOPS [1/409] HOPS identifier
5 A1 --- l_Fdisk Limit flag for Fdisk
7- 13 F7.2 mJy Fdisk [0/1588] Disk Flux
15- 19 F5.2 mJy e_Fdisk [0/34] Uncertainty in Fdisk
21- 26 F6.1 mJy Fapex [30.7/8883] APEX Flux
28 A1 --- l_Ipk Limit flag for Ipk
30- 36 F7.2 mJy/beam Ipk [1/3091] Beam flux at ACA peak
38 A1 --- l_Idisk Limit flag for Idisk
40- 46 F7.2 mJy/beam Idisk [0.9/3037] Beam flux at position of disk
48- 52 F5.2 mJy/beam I-rms [0.18/24] Mean RMS of map calculated from
three off-source positions
54 A1 --- l_Faca Limit flag for Faca
56- 62 F7.2 mJy Faca [1/4769] Integrated aperture flux
66- 70 F5.2 mJy Faca-rms [0.25/56.4] Calculated integrated flux
RMS (5)
72 A1 --- l_Fenv Limit flag for Fenv
74- 80 F7.2 mJy Fenv [-47/3540]? Envelope flux
82- 86 F5.2 mJy e_Fenv [0.26/60]? Uncertainty in Fenv
88 A1 --- l_FRatio Limit flag for FRatio
90- 93 F4.2 --- FRatio [0/3.63]? Flux ratio (6)
95- 98 F4.2 --- e_FRatio [0/1.6]? Uncertainty in FRatio
100 I1 --- Flag [1/2] Flag (7)
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Note (5): Calculated RMS of integrated flux from sixteen off-source positions
iterated with outlier rejection.
Note (6): Ratio of the 12m to ACA 870um flux densities (i.e. the relative
contribution of the disk flux to the total 870um flux) as in Equation 1:
R=Fν(12m)/Fν(ACA)=Fν(disk)/(Fν(disk)+Fν(env))
See Section 4.2
Note (7): Flag indicating the flux used in the analysis. Code as follows:
1 = Integrated aperture flux;
2 = Beam flux at position of disk.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 24-Jan-2025