J/MNRAS/500/3123 Star formation in the clumps of the NAN complex (Das+, 2021)
Testing the star formation scaling relations in the clumps of the North American
and Pelican nebulae cloud complex.
Das S.R., Jose J., Samal M.R., Zhang S., Panwar N.
<Mon. Not. R. Astron. Soc., 500, 3123-3141 (2021)>
=2021MNRAS.500.3123D 2021MNRAS.500.3123D (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; YSOs ; Interstellar medium ;
Star Forming Region ; Photometry, infrared
Keywords: stars: formation - ISM: clouds - ISM: dust -
ISM: individual objects: IC 5070 - ISM: individual objects: NGC 7000
Abstract:
The processes that regulate star formation within molecular clouds are
still not well understood. Various star formation scaling relations
have been proposed as an explanation, one of which is to formulate a
relation between the star formation rate surface density ΣSFR
and the underlying gas surface density Σgas. In this work, we
test various star formation scaling relations, such as the
Kennicutt-Schmidt relation, the volumetric star formation relation,
the orbital time model, the crossing time model and the multi
free-fall time-scale model, towards the North American Nebula and
Pelican Nebula and in the cold clumps associated with them. Measuring
stellar mass from young stellar objects and gaseous mass from CO
measurements, we estimate the mean ΣSFR, the star formation
rate per free-fall time and the star formation efficiency for clumps
to be 1.5M☉/yr/kpc2, 0.009 and 2.0 per cent, respectively,
while for the whole region covered by both nebulae (which we call the
'NAN' complex) the values are 0.6M☉/yr/kpc2, 0.0003 and 1.6
per cent, respectively. For the clumps, we notice that the observed
properties are in line with the correlation obtained between
ΣSFR and Σgas, and between ΣSFR and
Σgas per free-fall time and orbital time for Galactic clouds.
At the same time, we do not observe any correlation with Σgas
per crossing time and multi free-fall time. Even though we see
correlations in the former cases, however, all models agree with each
other within a factor of 0.5dex. It is not possible to discriminate
between these models because of the current uncertainties in the input
observables. We also test the variation of ΣSFR with the dense
gas but, because of low statistics, a weak correlation is seen in our
analysis.
Description:
Our analysis covers the region associated with North American Nebula
(NGC 7000) and the Pelican Nebula (IC 5070). Both nebulae are part of
the large HII region called W80 (Morgan, Stromgren & Johnson
1955ApJ...121..611M 1955ApJ...121..611M; Westerhout 1958BAN....14..215W 1958BAN....14..215W, Cat. VIII/64). We
call the whole region covered by these two nebulae the NAN complex
(Rebull et al. 2011ApJS..193...25R 2011ApJS..193...25R, Cat. J/ApJS/193/25; Zhang et al.
2014AJ....147...46Z 2014AJ....147...46Z, Cat. J/AJ/147/46). It is a nearby molecular cloud
complex and it is associated with many massive stars.
We use the MIR photometric data obtained from the Spitzer Space
Telescope (Werner et al. 2004ApJS..154....1W 2004ApJS..154....1W) with the IRAC (Fazio et
al. 2004ApJS..154...10F 2004ApJS..154...10F). The region towards the NAN complex is
studied in four IRAC bands by Guieu et al. (2009ApJ...697..787G 2009ApJ...697..787G, Cat.
J/ApJ/697/787) and in three bands of the MIPS (Rieke et al.
2004ApJS..154...25R 2004ApJS..154...25R) by Rebull et al. (2011ApJS..193...25R 2011ApJS..193...25R, Cat.
J/ApJS/193/25).
In this work, we retrieve NIR photometric data in J, H and K bands
from the Galactic Plane Survey (GPS; Lucas et al. 2008MNRAS.391..136L 2008MNRAS.391..136L,
Cat. II/316) of the UKIRT Infrared Deep Sky Survey (UKIDSS; Lawrence
et al. 2007MNRAS.379.1599L 2007MNRAS.379.1599L, Cat. II/314). This survey was carried out
with the UKIRT Wide Field Camera (WFCAM; Casali et al.
2007A&A...467..777C 2007A&A...467..777C). In our analysis, we use sources with an error
less than 0.2mag in all three bands.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 102 14 Physical parameters of the cold clumps
associated with the NAN complex
table3.dat 104 14 YSOs associated with all the cold clumps,
densities, star formation rate and efficiency
table4.dat 88 7 Physical parameters of the clumps associated
with dense regions
tablea1.dat 129 3038 List of all the 3038 YSOs associated with NAN
complex
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See also:
J/ApJ/697/787 : The NAN complex. I. IRAC observations (Guieu+, 2009)
J/ApJS/193/25 : The NAN complex. II. MIPS observations (Rebull+, 2011)
II/316 : UKIDSS-DR6 Galactic Plane Survey (Lucas+ 2012)
II/314 : UKIDSS-DR8 LAS, GCS and DXS Surveys (Lawrence+ 2012)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Complex Name of the complex
19- 20 I2 --- Clump [1/14] Internal clump identifier
22- 23 I2 h RAh Right ascension (J2000)
25- 26 I2 min RAm Right ascension (J2000)
28- 32 F5.2 s RAs Right ascension (J2000)
34 A1 --- DE- Declination sign (J2000)
35- 36 I2 deg DEd Declination (J2000)
38- 39 I2 arcmin DEm Declination (J2000)
41- 45 F5.2 arcsec DEs Declination (J2000)
47- 49 F3.1 pc r Clump radius (1)
51- 54 F4.2 pc e_r Error on r
56- 58 F3.1 10+21cm-2 NH2 Mean H2 column density NH2
60- 63 F4.1 10+24cm-2 SNH2 Total H2 column density ΣN(H2)
65- 68 I4 Msun Mass Clump mass (2)
70- 72 F3.1 Msun e_Mass Error on Mass
74- 76 F3.1 10+3cm-3 nH2 H2 volume number density nH2 (3)
78- 80 F3.1 10+3cm-3 e_nH2 Error on nH2
82- 86 F5.1 Msun/pc2 Sgas Gas surface density Σgas (4)
88- 90 F3.1 Msun/pc2 e_Sgas Error on Sgas
92- 95 F4.2 g/cm2 Sgascgs Gas surface density Σgas in
g/cm2
97- 102 F6.4 g/cm2 e_Sgascgs Error on Sgascgs
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Note (1): Using the clump apertures retrieved from ASTRODENDRO, we estimate the
physical sizes of the clumps (r=(A/π)0.5; Kauffmann & Pillai
2010ApJ...723L...7K 2010ApJ...723L...7K)
Note (2): The mass of the clumps is calculated using the following equation:
Mclump=µH2mHApixelΣN(H2), where mH is the mass
of hydrogen, Apixel is the pixel area in cm2, µH2 is the
mean molecular weight, which is assumed to be 2.8 (Kauffmann et al.
2008A&A...487..993K 2008A&A...487..993K, Cat. J/A+A/487/993), and ΣN(H2) is the
integrated column density
Note (3): The hydrogen volume number density is derived as:
nH2=3Mclump/(4πr3µH2mH), where r is the radius
Note (4): Surface density is derived as Σgas=Mclump/(πr2)
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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- 17 A17 --- Complex Name of the complex
19- 20 I2 --- Clump [1/14] Internal clump identifier
22- 24 I3 --- NYSOs Number of YSOs associated to the
clump
26- 29 F4.1 pc-2 NYSOs/area YSO density in clump
31- 34 F4.1 Msun/Myr SFR Star formation rate (1)
36- 38 F3.1 Msun/Myr e_SFR Error SFR
40- 42 F3.1 Msun/yr/kpc2 SFR/area Density of star formation rate in
clump
44- 46 F3.1 Msun/yr/kpc2 e_SFR/area Error on SFR/area
48- 50 F3.1 % SFE Star formation efficiency (2)
52- 56 F5.3 % e_SFE Error on SFE
58- 62 F5.1 Myr tdep Depletion time (3)
64- 68 F5.1 Myr e_tdep Error on tdep
70- 72 F3.1 Myr tff Free-fall time-scale (4)
74- 77 F4.2 Myr e_tff Error on tff
79- 82 F4.1 Myr tcross Crossing time (5)
84- 87 F4.1 Myr e_tcross Error on tcross
89- 93 F5.3 --- SFRff Star formation rate per free-fall
time (6)
95- 99 F5.1 Msun/yr/kpc2 Sgas/tmff Multi free-fall gas consumption rate
Σgas/tmultiff (7)
101- 104 F4.1 Msun/yr/kpc2 e_Sgas/tmff Error on Sgas/tmff
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Note (1): We derive the SFR for all the dense clumps using the following
relation: SFR=M*/τ, where M* is the total stellar mass within
a molecular clump, and τ is the average age of the molecular clump
Note (2): We calculate the SFE of the molecular clumps within the NAN complex
using SFE=M*/(M*+Mgas), where M* is the total YSO mass within
the clump and Mgas is the total mass of the clump
Note (3): The depletion time is expressed as tdep=Mgas/SFR
Note (4): We estimate the free-fall time-scale of the 14 dust clumps using the
relation : tff=(3π/(32GµmHnH2)1/2, where µ=2.8,
mH is the mass of the hydrogen atom, nH2 is the volume number
density of each clump and G is the gravitational constant
Note (5): We calculate the crossing time for each clump using the following
relation: tcross=2rcl/σv, where rcl is the clump radius
and σv is the dispersion velocity
Note (6): We have derived the SFR per free-fall time of the 14 dust clumps of
the NAN complex using the relation: SFRff=tff/tdep
Note (7): The quantity Σgas/tmultiff is the maximum gas consumption
rate or multi free-fall gas consumption rate (MGCR) and we have:
Σgas/tmultiff=Σgas/tffexp(3σs2/8),
where σs2 is the logarithmic dispersion. The logarithmic
dispersion is expressed as:
σs2=ln(1+b2M2β/(β+1)), where M is the sonic
Mach number, b is the turbulent driving parameter and β is the
ratio of thermal to magnetic pressure plasma. See Section 4.4.5 of
the article for more details.
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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 I1 --- Clump [1/7] Internal dense clump identifier
3- 4 I2 h RAh Right ascension (J2000)
6- 7 I2 min RAm Right ascension (J2000)
9- 13 F5.2 s RAs Right ascension (J2000)
15 A1 --- DE- Declination sign (J2000)
16- 17 I2 deg DEd Declination (J2000)
19- 20 I2 arcmin DEm Declination (J2000)
22- 26 F5.2 arcsec DEs Declination (J2000)
28- 30 F3.1 pc r Clump radius
32- 35 F4.2 pc e_r Error on r
37- 40 I4 Msun Mass Clump mass
42 I1 Msun e_Mass Error on Mass
44- 48 F5.1 Msun/pc2 Sgas Gas surface density Σgas
50- 52 F3.1 Msun/pc2 e_Sgas Error on Sgas
54- 57 F4.2 g/cm2 Sgascgs Gas surface density Σgas in
g/cm2
59- 64 F6.4 g/cm2 e_Sgascgs Error on Sgascgs
66- 67 I2 --- NYSOs Number of YSOs associated to the clump
69- 71 F3.1 pc-2 N/area YSO density in clump
73- 76 F4.1 Msun/Myr SFR Star formation rate
78- 80 F3.1 Msun/Myr e_SFR Error on SFR
82- 84 F3.1 Msun/yr/kpc2 SFR/area Density of star formation rate in
clump
86- 88 F3.1 Msun/yr/kpc2 e_SFR/area Error on SFR/area
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- YSO [1/3038] Internal YSO identifier
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 29 F5.2 arcsec DEs Declination (J2000)
31- 35 F5.2 mag Jmag ?=0 UKIRT/WFCAM J-band magnitude
37- 40 F4.2 mag e_Jmag ?=0 Error on Jmag
42- 46 F5.2 mag Hmag ?=0 UKIRT/WFCAM H-band magnitude
48- 51 F4.2 mag e_Hmag ?=0 Error on Hmag
53- 57 F5.2 mag Kmag ?=0 UKIRT/WFCAM K-band magnitude
59- 62 F4.2 mag e_Kmag ?=0 Error on Kmag
64- 68 F5.2 mag 3.6mag ?=0 Spitzer/IRAC 3.6um magnitude
70- 73 F4.2 mag e_3.6mag ?=0 Error on 3.6mag
75- 79 F5.2 mag 4.5mag ?=0 Spitzer/IRAC 4.5um magnitude
81- 84 F4.2 mag e_4.5mag ?=0 Error on 4.5mag
86- 90 F5.2 mag 5.8mag ?=0 Spitzer/IRAC 5.8um magnitude
92- 96 F5.2 mag e_5.8mag ?=0 Error on 5.8mag
98- 102 F5.2 mag 8.0mag ?=0 Spitzer/IRAC 8.0um magnitude
104- 108 F5.2 mag e_8.0mag ?=0 Error on 8.0mag
110- 114 F5.2 mag 24.0mag ?=0 Spitzer/MIPS 24um magnitude
116- 120 F5.2 mag e_24.0mag ?=0 Error on 24.0mag
122- 129 A8 --- Class YSO classification
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 04-Oct-2023