J/PASJ/72/55 L1482 filament cores (Omodaka+, 2020)
Star formation rates in the L 1482 filament of the California molecular cloud.
Omodaka T., Nagayama T., Dobashi K., Chibueze J.O., Yamabi A.,
Shimajiri Y., Inoue S., Hamada S., Sunada K., Ueno Y.
<Publ. Astron. Soc. Jap., 72, 55 (2020)>
=2020PASJ...72...55O 2020PASJ...72...55O (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Masers ; Radio sources
Keywords: masers - astrometry stars: formation - stars: individual
Abstract:
We measured the trigonometric parallax of the H2O maser source
associated with the L1482 molecular filament hosting the most massive
young star, LkHα 101, in the California molecular cloud. The
measured parallax is 1.879±0.096mas, corresponding to the distance
of 532±28pc. This parallax is consistent with that of the nearby
star cluster LkHα 101, which was recently measured with Gaia
DR2. We found that the L1482 molecular filament and the LkHα
101 cluster are located at the same distance within 3±30pc. We
observed the southern parts of L1482 molecular clouds including the
H2O maser source, which is adjacent to LkHα 101, using the
Nobeyama 45m telescope in the J=1-0 transitions of both 12CO and
13CO. The peak intensity of the 12CO line revealed the high
excitation temperature region (60-70K) due to heating by UV radiation
from LkHα 101. We derived the column density of these molecular
clouds assuming local thermodynamic equilibrium (LTE) from the 13CO
emission. Using Dendrogam, we searched for small-scale, dense
structures (cores) and identified 337 cores in the 13CO data.
Gravitationally bound cores with a virial mass to LTE mass ratio ≤1.5
and young stars are concentrated in the high excitation temperature
region. The column density in the warm region is five to six times
larger than that of the surrounding colder molecular region. This
suggests that the warm region has been compressed by a high-pressure
wave and successive radiation-driven star formation is in progress in
this warm region. In the cold molecular cloud to the north of the warm
region, the cores are likely gravitationally unbound, which may be the
reason why star formation is not active there.
Description:
The VLBI observations of the 22.235080GHz H2O maser in L1482 were
carried out on 2010/333, 2011/016, 2011/113, 2011/228, 2011/297, and
2011/353 (year/day of the year) with VERA. The observing time was
approximately eight hours at each epoch.
In order to study the star formation activity in the L1482 filament,
we identified cores using the fiducial core-finding algorithm
Dendrogram (Rosolowsky et al. 2008ApJ...679.1338R 2008ApJ...679.1338R).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 81 337 Properties of identified cores using dendrogram
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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 --- ID Sequential number
6 I1 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 15 F5.2 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 27 F4.1 arcsec DEs Declination (J2000)
29- 33 F5.3 pc Rcore Core radius
35- 40 F6.3 K Tpeak Peak temperature
42- 45 F4.1 K backg Background level
47- 51 F5.3 km/s DV Line width
53- 57 F5.2 Msun Mvir Virial mass
59- 63 F5.2 10+23cm-2 SNH2 Total molecular column density
65- 69 F5.2 Msun MLTE LTE mass
71- 75 F5.2 10+3cm-3 n Mean molecular number density
77- 81 F5.2 --- Mvir/MLTE Virial to core mass ratio (=αvir)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Nov-2023