J/ApJS/235/30 Herschel-PACS legacy of low-mass protostars (Karska+, 2018)
The Herschel-PACS legacy of low-mass protostars: the properties of warm and hot
gas components and their origin in far-UV illuminated shocks.
Karska A., Kaufman M.J., Kristensen L.E., van Dishoeck E.F., Herczeg G.J.,
Mottram J.C., Tychoniec L., Lindberg J.E., Evans II N.J., Green J.D.,
Yang Y.-L., Gusdorf A., Itrich D., Siodmiak N.
<Astrophys. J. Suppl. Ser., 235, 30-30 (2018)>
=2018ApJS..235...30K 2018ApJS..235...30K (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium; YSOs; Infrared sources; Stars, distances;
Molecular clouds; Star Forming Region
Keywords: infrared: ISM; ISM: jets and outflows; ISM: molecules
Abstract:
Recent observations from Herschel allow the identification of
important mechanisms responsible both for the heating of the gas that
surrounds low-mass protostars and for its subsequent cooling in the
far-infrared. Shocks are routinely invoked to reproduce some
properties of the far-IR spectra, but standard models fail to
reproduce the emission from key molecules, e.g., H2O. Here, we
present the Herschel Photodetector Array Camera and Spectrometer
(PACS) far-IR spectroscopy of 90 embedded low-mass protostars
(Class 0/I). The Herschel-PACS spectral maps, covering ∼55-210µm
with a field of view of ∼50", are used to quantify the gas excitation
conditions and spatial extent using rotational transitions of H2O,
high-J CO, and OH, as well as [OI] and [CII]. We confirm that a warm
(∼300K) CO reservoir is ubiquitous and that a hotter component
(760±170K) is frequently detected around protostars. The line
emission is extended beyond ∼1000au spatial scales in 40/90 objects,
typically in molecular tracers in Class 0 and atomic tracers in
Class I objects. High-velocity emission (≳90km/s) is detected in only
10 sources in the [OI] line, suggesting that the bulk of [OI] arises
from gas that is moving slower than typical jets. Line flux ratios
show an excellent agreement with models of C-shocks illuminated by
ultraviolet (UV) photons for pre-shock densities of ∼105cm-3 and
UV fields 0.1-10 times the interstellar value. The far-IR molecular
and atomic lines are a unique diagnostic of feedback from UV emission
and shocks in envelopes of deeply embedded protostars.
Description:
The low-mass embedded protostars analyzed here were initially observed
as part of the WISH (van Dishoeck+ 2011PASP..123..138V 2011PASP..123..138V) and "Dust,
Ice, and Gas In Time" (DIGIT, Green+ 2013ApJ...770..123G 2013ApJ...770..123G) surveys,
which comprised 18 and 29 protostars targeted with PACS, respectively,
including eight overlap sources. This sample was subsequently expanded
by the WILL survey (Mottram+ 2017A&A...600A..99M 2017A&A...600A..99M), where a further
49 sources were observed, including 37 Class 0/I objects. Three
additional sources were located in the PACS spectral maps of the
primary targets, increasing the sample to 90 sources in total (for
details, see Table 1).
Single-footprint spectral maps of all sources were obtained with the
PACS instrument onboard Herschel. Each map consists of 25 spatial
pixels (spaxels) of 9.4"x9.4", arranged in a 5x5 array with a total
field of view of ∼47"x47". Each spaxel contains a (sub-)spectrum
observed in the first (red) or second (blue) order, within the
wavelength ranges of 102-210um and 51-105um, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 90 Luminosities and bolometric temperatures of
embedded protostars
table3.dat 86 90 Rotational temperatures and numbers of emitting
molecules
table4.dat 53 90 Total line luminosities of H2O, CO, OH, and [OI]
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See also:
VI/139 : Herschel Observation Log (Herschel Science Centre, 2013)
J/ApJ/692/973 : Protostars in Perseus, Serpens and Ophiuchus (Enoch+, 2009)
J/A+A/498/167 : Embedded sources in L 1688 (van Kempen+, 2009)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/MNRAS/406/1745 : H2O in interstellar shock waves (Flower+, 2010)
J/A+A/550/A106 : Low-velocity shocks models (Lesaffre+, 2013)
J/ApJ/767/36 : APEX observations of HOPS protostars (Stutz+, 2013)
J/A+A/568/A125 : NGC 1333 IRAS 4A H2O observations (Santangelo+, 2014)
J/A+A/572/A21 : H2O sp. of 29 nearby Class 0/I protostars (Mottram+, 2014)
J/A+A/576/A109 : YSOs APEX-CHAMP+ high-J CO maps (Yildiz+, 2015)
J/A+A/578/A63 : MHD shock code mhd_vode (Flower+, 2015)
J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)
J/ApJ/818/73 : Protostars in the Perseus molecular cloud (Tobin+, 2016)
J/AJ/151/75 : Herschel-PACS & -SPIRE spectrosc. of 70 objects (Green+, 2016)
J/A+A/594/A59 : Far-IR lines in YSOs Herschel-PACS (Riviere-Marichalar+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/90] Running sequence number
4- 5 I2 h RAh Hour of right ascension (J2000)
7- 8 I2 min RAm Minute of right ascension (J2000)
10- 14 F5.2 s RAs Second of right ascension (J2000)
16 A1 --- DE- Sign of declination (J2000)
17- 18 I2 deg DEd Degree of declination (J2000)
20- 21 I2 arcmin DEm Arcminute of declination (J2000)
23- 26 F4.1 arcsec DEs Arcsecond of declination (J2000)
28- 31 A4 --- Cloud Cloud name
33- 35 I3 pc Dist [106/450] Distance (1)
37- 41 F5.1 Lsun Lbol [0.1/108.7] Bolometric luminosity
43- 46 F4.1 % Rlum [0.1/27.3]? Ratio of submm luminosity to
bolometric luminosity
48- 50 I3 K Tbol [14/605] Bolometric temperature
52- 58 A7 --- Class YSO class
60- 95 A36 --- OName Other name(s) (2)
97- 101 A5 --- Survey Survey identifier(s) (3)
103 A1 --- f_Seq e: Sources with extended line and
continuum emission (see Table 2);
flag added by CDS
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Note (1): Distances come from van Dishoeck+ (2011PASP..123..138V 2011PASP..123..138V) for the
WISH sources, Green+ (2013ApJ...770..123G 2013ApJ...770..123G) for the DIGIT sources, and
Mottram+ (2017A&A...600A..99M 2017A&A...600A..99M) for the WILL sources with the exception
of sources in Serpens, which have been updated to use the latest
distance by Ortiz-Leon+ (2017ApJ...834..143O 2017ApJ...834..143O). PS refers to possible
pre-stellar cores and PDR to photodissociation regions.
Note (2): Numbered Per-emb and Oph-emb names come from
Enoch+ (2009, J/ApJ/692/973). Aqu, SerpS, and W40 numbered names are
from Maury+ (2011A&A...535A..77M 2011A&A...535A..77M). Chamaeleon names come from
Spezzi+ (2013A&A...555A..71S 2013A&A...555A..71S) and Winston+ (2012A&A...545A.145W 2012A&A...545A.145W). The
final entries are other names used by the WILL program, and therefore
also in the Herschel archive.
Note (3): Survey names as follows:
D = The "Dust, Ice, and Gas in Time" (DIGIT) open time program
(Green+ 2013ApJ...770..123G 2013ApJ...770..123G)
WH = The "Water in Star-forming regions with Herschel" (WISH) survey
(van Dishoeck+ 2011PASP..123..138V 2011PASP..123..138V)
WL = the "William Herschel Line Legacy" (WILL) open time survey
(Mottram+ 2017A&A...600A..99M 2017A&A...600A..99M) programs on Herschel with
PACS and HIFI spectra.
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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- 2 I2 --- Seq [1/90] Running sequence number
4- 14 A11 --- Source Source name
16- 18 I3 K TCO14-26 [177/562]? CO Jup=14-26 rotational
temperature
20- 22 I3 K e_TCO14-26 [8/146]? TCO14-26 uncertainty
24- 27 F4.1 [-] logN14-26 [47/50.6]? CO Jup=14-26 log number of
emitting molecules
29- 31 F3.1 [-] e_logN14-26 [0/0.5]? logN14-26 uncertainty
33- 36 I4 K TCOg27 [488/1089]? CO Jup≥27 rotational
temperature
38- 40 I3 K e_TCOg27 [10/411]? TCOg27 uncertainty
42- 45 F4.1 [-] logNg27 [47/49.7]? CO Jup≥27 log number of
emitting molecules
47- 49 F3.1 [-] e_logNg27 [0.1/0.7]? logNg27 uncertainty
51- 53 I3 K TH2O [51/310]? H2O rotational temperature
55- 57 I3 K e_TH2O [9/202]? TH2O uncertainty
59- 62 F4.1 [-] logNH2O [44.4/47.3]? H2O log number of emitting
molecules
64- 66 F3.1 [-] e_logNH2O [0.1/1.1]? logNH2O uncertainty
68- 70 I3 K TOH [33/150]? OH rotational temperature
72- 74 I3 K e_TOH [3/214]? TOH uncertainty
76- 79 F4.1 [-] logNOH [50.4/54.2]? OH log number of emitting
molecules
81- 83 F3.1 [-] e_logNOH [0.2/1.2]? logNOH uncertainty
85- 86 A2 --- Mode Mode: F=full or L=line spectroscopy with
PACS
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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- 2 I2 --- Seq [1/90] Running sequence number
4- 8 F5.2 10-3Lsun LH2O [0/66.1]? Total H2O luminosity
10- 15 F6.2 10-3Lsun LCOwarm [0.01/143]? Total CO Jup=14-26 luminosity
17- 21 F5.2 10-3Lsun LCOhot [0.01/30]? Total CO Jup≥27 luminosity
23- 27 F5.2 10-3Lsun LOH [0/32]? Total OH luminosity
29- 34 F6.2 10-3Lsun LOI63 [0.02/148]? Total [OI]63um luminosity
36- 42 F7.3 10-3Lsun LOItot [0.02/158]? Total [OI] luminosity (sum of
the line luminosities of the [OI] lines
at 63 and 145um)
44- 53 A10 --- Notes Note(s) (1)
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Note (1): Notes as follows:
c = values derived from line scans and corrected for the missing lines;
no = non-detection of the [OI] line at 145um;
oc = contamination of the [OI] emission on the map;
lw = lower limit of the H2O
lc = lower limit of the CO warm
lh = lower limit of the CO hot
loh = lower limit of the OH
lm = lower limit of all molecules
h = line luminosities of CO hot are added to the CO warm.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 10-Oct-2023