J/ApJ/927/213 3mm & 2mm maps of seven cores in L1495 filament (Punanova+, 2022)
Methanol mapping in cold cores: testing model predictions.
Punanova A., Vasyunin A., Caselli P., Howard A., Spezzano S., Shirley Y.,
Scibelli S., Harju J.
<Astrophys. J., 927, 213 (2022)>
=2022ApJ...927..213P 2022ApJ...927..213P
ADC_Keywords: Star Forming Region; Millimetric/submm sources;
Interstellar medium
Keywords: Star forming regions ; Interstellar molecules ;
Molecule formation ; Submillimeter astronomy ; Astrochemistry
Abstract:
Chemical models predict that in cold cores gas-phase methanol is
expected to be abundant at the outer edge of the CO depletion zone,
where CO is actively adsorbed. CO adsorption correlates with volume
density in cold cores, and, in nearby molecular clouds, catastrophic
CO freeze-out happens at volume densities above 104cm-3. The
methanol production rate is maximized there and its freeze-out rate
does not overcome its production rate, while the molecules are
shielded from UV destruction by gas and dust. Thus, in cold cores,
methanol abundance should generally correlate with visual extinction,
which depends on both volume and column density. In this work, we test
the most basic model prediction that maximum methanol abundance is
associated with a local AV∼4mag in dense cores and constrain the
model parameters with the observational data. With the IRAM 30m
antenna, we mapped the CH3OH(2-1) and (3-2) transitions toward seven
dense cores in the L1495 filament in Taurus to measure the methanol
abundance. We use the Herschel/SPIRE maps to estimate visual
extinction, and the C18O(2-1) maps from Tafalla & Hacar to estimate
CO depletion. We explored the observed and modeled correlations
between the methanol abundances, CO depletion, and visual extinction,
varying the key model parameters. The modeling results show that
hydrogen surface diffusion via tunneling is crucial to reproduce the
observed methanol abundances, and the necessary reactive desorption
efficiency matches the one deduced from laboratory experiments.
Description:
We mapped six methanol lines at 96.7GHz and 145.1GHz toward seven
dense cores of the L1495 filamentary structure (see Figure 1 and
Tables 1 and 2) with the IRAM 30m telescope (IRAM projects 013-18,
125-18, and 031-19). The observations were performed on 2018 October
17-23, 2019 March 27-29, and 2019 September 16 under acceptable
weather conditions, with precipitable water vapor pwv=1-10mm. The
on-the-fly maps were obtained with the EMIR 090 (3mm band) and EMIR
150 (2mm band) eight-mixer heterodyne receivers 6 in position
switching mode and the VESPA (Versatile Spectrometer Assembly)
backend. The spectral resolution was 20kHz; the corresponding velocity
resolutions were ∼0.06km/s for the 3mm band and ∼0.04km/s for the 2mm.
The beam sizes were ∼26" for the 3mm band and ∼17" for the 2mm.
Objects:
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RA (ICRS) DE Designation(s)
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04 18 06 +27 37 L1495 = LDN 1495
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 7 The mapped cores
fits/* . 14 *Individual spectral cubes in FITS format
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Note on fits/*: The 14 .fits files contain spectral data cubes with
3mm and 2mm methanol lines, (2-1) at 96.74GHz and (3-2) at 145.10GHz
rotational transitions toward dense cores in the L1495 filament. There
are two cubes (3 and 2mm) for each core. The cubes have common 26.8"
beam and 8.7" pixel size. The spectral resolution is 0.04, 0.06 and
0.10km/s (see the individual headers).
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See also:
VII/220 : Barnard's Catalogue of 349 Dark Objects in the Sky (Barnard, 1927)
VII/7 : Lynds' Catalogue of Dark Nebulae (LDN) (Lynds 1962)
J/A+A/432/369 : Leiden Atomic & Molecular Database (LAMDA) (Schoeier+, 2005)
J/ApJS/186/259 : Taurus Spitzer survey: new candidate members (Rebull+, 2010)
J/A+A/554/A55 : C18O(1-0) and N2H+(1-0) in L1495/B213 (Hacar+, 2013)
J/ApJ/786/29 : Catalog of distances to molecular clouds (Schlafly+, 2014)
J/A+A/574/A104 : Dense cores in L1495/B213 complex (Tafalla+, 2015)
J/MNRAS/463/1008 : LDN 1495 SCUBA-2 and Herschel data (Ward-Thompson+, 2016)
J/A+A/604/A52 : B213 filament 150 and 260GHz emission maps (Bracco+, 2017)
J/A+A/606/A142 : L1544 1.2 and 2mm emission maps (Chacon-Tanarro+, 2017)
J/A+A/617/A27 : Kinematics of dense gas in L1495 filament (Punanova+, 2018)
J/A+A/624/A108 : Modeling interstellar sulfur depletion (Laas+, 2019)
J/A+A/630/A136 : Starless core L1521E chemical structure (Nagy+, 2019)
J/A+A/638/A74 : Dense cores in Oph molecular cloud (Ladjelate+, 2020)
J/A+A/633/A118 : 3mm-band study of L183 and L1544 (Lattanzi+, 2020)
J/A+A/638/A85 : Taurus with Gaia & Herschel (Roccatagliata+, 2020)
J/A+A/643/A60 : Starless cores CH3OH and c-C3H2 maps (Spezzano+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID [1/16]? Identifier of the dense core in
Hacar+ 2013, J/A+A/554/A55 ;
(<[HTK2013] NN> in Simbad)
4 A1 --- f_ID [*] *: protostellar core
6- 15 A10 --- Core Name of the dense core in
Seo+ 2015ApJ...805..185S 2015ApJ...805..185S ;
(<[SSG2015] NN> in Simbad)
17- 18 I2 h RAh [4] Hour of right ascension (J2000) (1)
20- 21 I2 min RAm [17/24] Minute of right ascension (J2000)
23- 28 F6.3 s RAs Second of right ascension (J2000)
30 A1 --- DE- [+] Sign of declination (J2000) (1)
31- 32 I2 deg DEd [26/28] Degree of declination (J2000) (1)
34- 35 I2 arcmin DEm Arcminute of declination (J2000)
37- 41 F5.2 arcsec DEs Arcsecond of declination (J2000)
43- 46 A4 --- Reg Region identifier according to
Barnard 1927, VII/220 ;
(<Barnard NNN> in Simbad)
48- 67 A20 --- FileName1 Name of the FITS file in subdirectory "fits"
for the CH3OH(2-1) line at 96.74GHz (3mm)
69- 88 A20 --- FileName2 Name of the FITS file in subdirectory "fits"
for the CH3OH(3-2) line at 145.10GHz (2mm)
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Note (1): The given coordinates are the central positions of the maps.
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Acknowledgements:
Anna Punanova [punanovaanna at gmail dot com] for the Seo35 files
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 19-Jan-2024