J/ApJ/772/45 Hi-GAL obs.: star formation in the third quadrant (Elia+, 2013)
The first Hi-GAL observations of the outer galaxy: a look at star formation in
the third galactic quadrant in the longitude range 216.5°≲l≲225.5°.
Elia D., Molinari S., Fukui Y., Schisano E., Olmi L., Veneziani M.,
Hayakawa T., Pestalozzi M., Schneider N., Benedettini M., di Giorgio A.M.,
Ikhenaode D., Mizuno A., Onishi T., Pezzuto S., Piazzo L., Polychroni D.,
Rygl K.L.J., Yamamoto H., Maruccia Y.
<Astrophys. J., 772, 45 (2013)>
=2013ApJ...772...45E 2013ApJ...772...45E
ADC_Keywords: Interstellar medium ; Photometry, infrared ; Radio lines ;
Velocity dispersion ; Molecular clouds ; Milky Way
Keywords: Galaxy: structure; infrared: ISM; ISM: clouds; ISM: molecules;
stars: formation
Abstract:
We present the first Herschel PACS and SPIRE photometric observations
in a portion of the outer Galaxy (216.5°≲l≲225.5° and
-2°≲b≲0°) as a part of the Hi-GAL survey. The maps between
70 and 500µm, the derived column density and temperature maps, and
the compact source catalog are presented. NANTEN CO(1-0) line
observations are used to derive cloud kinematics and distances so that
we can estimate distance-dependent physical parameters of the compact
sources (cores and clumps) having a reliable spectral energy
distribution that we separate into 255 proto-stellar and 688 starless
sources. Both typologies are found in association with all the
distance components observed in the field, up to ∼5.8kpc, testifying
to the presence of star formation beyond the Perseus arm at these
longitudes. Selecting the starless gravitationally bound sources, we
identify 590 pre-stellar candidates. Several sources of both proto-
and pre-stellar nature are found to exceed the minimum requirement for
being compatible with massive star formation based on the mass-radius
relation. For the pre-stellar sources belonging to the Local arm
(d≲1.5kpc) we study the mass function whose high-mass end shows a
power law N(logM)∝M-1.0±0.2. Finally, we use a luminosity
versus mass diagram to infer the evolutionary status of the sources,
finding that most of the proto-stellar sources are in the early
accretion phase (with some cases compatible with a Class I stage),
while for pre-stellar sources, in general, accretion has not yet
started.
Description:
The outer Galaxy was surveyed by the Herschel Space Observatory as
part of the Hi-GAL key project (Molinari et al. 2010PASP..122..314M 2010PASP..122..314M),
selecting a range of longitudes (216.5°≲l≲225.5°) in the
third Galactic quadrant (TGQ), also covered by a CO(1-0) line map
obtained with the NANTEN radio telescope.
The 2.3°x2.3° fields presented in this paper were observed
with Herschel/PACS (70 and 160um) and /SPIRE (250, 350 and 500um)
between 2011 May 5 and 9.
The NANTEN CO(J=1-0) Galactic Plane Survey data set (Mizuno & Fukui
2004ASPC..317...59M 2004ASPC..317...59M) was used in the present analysis. At the time of
the observations, carried out in a period from 1996 to 2003, the 4m
NANTEN millimeter-wave telescope of Nagoya University was installed at
Las Campanas Observatory in Chile.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 59 321 List of the clumps detected in the CO(1-0) line
table3.dat 119 943 List of the analyzed Hi-GAL sources
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See also:
VI/139 : Herschel Observation Log (Herschel Science Centre, 2013)
VII/50 : CO Radial Velocities Toward Galactic H II Regions (Blitz+ 1982)
VII/7 : Lynds' Catalogue of Dark Nebulae (LDN) (Lynds 1962)
VII/20 : Catalogue of HII Regions (Sharpless 1959)
J/A+A/549/A130 : YSOs in Herschel-Hi-GAL survey (Veneziani+, 2013)
J/A+A/537/A1 : Infrared fluxes of HII regions and PNe (Anderson+, 2012)
J/A+A/526/A151 : Hi-Gal sources distance determination (Russeil+, 2011)
J/AJ/137/4072 : Infrared photometry of G216-2.5 YSOs (Megeath+, 2009)
J/ApJ/686/948 : CO in extragalactic giant molecular clouds (Bolatto+, 2008)
J/ApJ/684/1240 : Prestellar cores in Perseus, Serpens & Oph. (Enoch+, 2008)
J/ApJ/672/930 : Distant CO clouds in third galactic quadrant (Vazquez+, 2008)
J/A+A/481/345 : SED evolution in massive YSOs (Molinari+, 2008)
J/A+A/462/L17 : Dense cores in interstellar molecular clouds (Alves+, 2007)
J/ApJ/665/1194 : Dense cores in the Orion A cloud survey (Ikeda+, 2007)
J/PASJ/56/313 : 13CO survey of Mon + CMa molecular clouds (Kim+, 2004)
J/ApJS/144/47 : Outer galaxy molecular cloud catalog (Brunt+, 2003)
J/A+A/327/325 : Distances of molecular cloud (May+, 1997)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/321] Clump running sequence number
5- 13 F9.5 deg GLON Galactic longitude
15- 22 F8.5 deg GLAT Galactic latitude
24- 27 F4.1 km/s VLSR [0/65] Local Standard of Rest velocity
29- 31 F3.1 km/s sigma [0.4/3] Velocity dispersion (1)
33- 35 F3.1 kpc Dist [0.2/7.5] Heliocentric distance (2)
37- 40 F4.1 pc Rad [0.3/20] Deconvolved radius (3)
42- 46 I5 Msun Mass [4/47071] Clump mass (4)
48- 52 I5 Msun Mvir [283/72960] Virial mass (5)
54- 59 F6.1 K.km/s.pc2 Lum [0.6/6139] The CO(1-0) line luminosity (6)
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Note (1): Velocity dispersion is derived as the second moment of the intensity
distribution along the velocity dimension.
Note (2): To derive the heliocentric distances, the Galactic rotation curve of
Brunthaler et al. (2011AN....332..461B 2011AN....332..461B, R0=8.3kpc,
θ0=239km/s) has been used instead of the default one of
Reid et al. (2009ApJ...700..137R 2009ApJ...700..137R) implemented in CLOUDPROPS.
Note (3): The deconvolved radius r is estimated as the geometric mean of the
deconvolved major and minor axes of the clump.
Note (4): The mass of the clump is obtained as in Section 3.1, i.e.,
integrating the column density over the solid angle of the clump.
See also section 4.2 for further details.
Note (5): The virial mass is calculated as:
Mvir[M☉]=1040σv2[km/s]r[pc], under the assumption
that each clump is spherical and virialized with a density profile of
the form ρ∝r-1 (Solomon et al. 1987ApJ...319..730S 1987ApJ...319..730S).
Density power laws with exponents 0 and -2 would require, instead, a
constant of 1150 and 690M☉(km/s)-1/pc, respectively.
Note (6): The conversion factor to solar luminosities for this transition is
4.9x10-5L☉[K.km/s.pc2]-1
(Solomon et al. 1992ApJ...398L..29S 1992ApJ...398L..29S).
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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- 3 I3 --- Seq [1/943] Source running sequence number
5- 13 F9.5 deg GLON Galactic longitude
15- 22 F8.5 deg GLAT Galactic latitude
24- 26 F3.1 kpc Dist [0.4/7.5] Distance
28- 33 F6.2 Jy F70 ? Herschel/PACS 70 micron band flux density
35- 38 F4.2 Jy e_F70 ? Uncertainty in F70
40- 45 F6.2 Jy F160 ? Herschel/PACS 160 micron band flux density
47- 50 F4.2 Jy e_F160 ? Uncertainty in F160
52- 57 F6.2 Jy F250 [0.1/223] Herschel/SPIRE 250um band flux density
59- 63 F5.2 Jy e_F250 [0.02/38] Uncertainty in F250
65- 69 F5.2 Jy F350 Herschel/SPIRE 350 micron band flux density
71- 75 F5.2 Jy e_F350 Uncertainty in F350
77- 81 F5.2 Jy F500 ? Herschel/SPIRE 500 micron band flux density
83- 87 F5.2 Jy e_F500 ? Uncertainty in F500
89- 92 F4.1 arcsec Rad [1.2/79] Angular radius
94- 98 F5.1 Msun Mass [0/729] Mass
100-103 F4.1 K Temp [7.1/44] Temperature
105-110 F6.2 Jy F22 [0.01/475]? WISE 22 micron band flux density
112-117 F6.1 Lsun Lbol [0/9680] Bolometric luminosity
119 I1 --- Flag [0/2]? Source flag (1)
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Note (1): Flag as follows:
0 = unbound;
1 = pre-stellar;
2 = proto-stellar.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 30-Jan-2015