J/ApJ/702/178 YSOs in the central 400pc of the Galaxy (Yusef-Zadeh+, 2009)
Star formation in the central 400 pc of the Milky Way:
evidence for a population of massive young stellar objects.
Yusef-Zadeh F., Hewitt J.W., Arendt R.G., Whitney B., Rieke G., Wardle M.,
Hinz J.L., Stolovy S., Lang C.C., Burton M.G., Ramirez S.
<Astrophys. J., 702, 178-225 (2009)>
=2009ApJ...702..178Y 2009ApJ...702..178Y
ADC_Keywords: Infrared sources ; Milky Way ; YSOs ; Stars, masses
Keywords: galaxies: starburst - Galaxy: center - ISM: clouds - masers -
stars: formation
Abstract:
The central kpc of the Milky Way might be expected to differ
significantly from the rest of the Galaxy with regard to gasdynamics
and the formation of young stellar objects (YSOs). We probe this
possibility with mid-infrared observations obtained with Infrared
Array Camera and Multiband Imaging Photometer on Spitzer and with
Midcourse Space Experiment. We use color-color diagrams and spectral
energy distribution (SED) fits to explore the nature of YSO candidates
(including objects with 4.5um excesses possibly due to molecular
emission). We use the SEDs of these sources to estimate their physical
characteristics; their masses appear to range from ∼10 to ∼20M☉.
Description:
The source photometry was based on the 24um catalog compiled by Hinz
et al. (2009, Cat. J/ApJS/181/227). Our data are complemented by the
Spitzer Legacy program MIPS Inner Galactic Plane Survey (MIPSGAL)
which observed 220degrees2 of the inner Galactic plane at 24 and
70um (Carey et al. 2009PASP..121...76C 2009PASP..121...76C).
In order to obtain more complete SEDs of some of the high latitude
24um sources that show excess emission at 4.5um, we selected a total
of nine such sources distributed at high Galactic latitudes within our
survey. These sources were observed separately with MIPS at 70um
between 2007 September 21 and 23.
We obtained 32 overlapping images at 20cm from two surveys:
Yusef-Zadeh et al. 2004, Cat. J/ApJS/155/421 and Law et al. 2008, Cat.
J/ApJS/177/255. C. C. Lang et al. (2011ASPC..439...53L 2011ASPC..439...53L) have completed
a 6cm survey of the Galactic center region with a uniform uv coverage.
We have used this data set to measure the fluxes of several point
sources in the G359.43+0.02 cluster.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 61 18 Galactic coordinates and flux density of
sources in G359.43+0.02
table3.dat 88 223 parameters of the SED fits to candidate YSOs
in l<0°
table4.dat 88 137 parameters of the SED fits to candidate YSOs
in l>0°
table5.dat 69 33 Table of sources with 4.5um Excess Emission
table6.dat 58 9 Table of 70um Sources
table7.dat 55 21 Table of Methanol class I maser sources
table8.dat 55 23 Table of Methanol class II maser sources
table9.dat 90 14 Parameters of SED fits to 4.5um excess sources
near the Galactic Center
table10.dat 88 19 parameters of SED fits to 4.5um excess sources
foreground to the Galactic Center
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See also:
II/295 : Spitzer IRAC survey of the galactic center (Ramirez+, 2008)
J/ApJS/181/227 : Catalog of 24um sources toward Galactic Center (Hinz+, 2009)
J/ApJ/697/1741 : Warped disks of YSOs in Galactic center (Bartko+, 2009)
J/ApJS/177/255 : GBT multiwavelength survey of Galactic center (Law+, 2008)
J/A+A/453/535 : Classification of bright mid-IR sources (Schuller+, 2006)
J/ApJ/643/1011 : Early-type stars in the center of the Galaxy (Paumard+, 2006)
J/ApJS/155/421 : Survey of Galactic Center region at 20cm (Yusef-Zadeh+, 2004)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- [YHA2009] Source number
3 A1 --- m_[YHA2009] [e] e: Extended component
5 A1 --- n_[YHA2009] [abc] Individual notes (1)
7- 16 F10.6 deg GLON Galactic longitude
18- 26 F9.6 deg GLAT Galactic latitude
28- 31 F4.1 --- S6cm ? VLA 6cm flux density
33- 36 F4.1 --- e_S6cm ? S6cm uncertainty
38- 41 F4.1 --- S20cm ? VLA 20cm flux density
43- 46 F4.1 --- e_S20cm ? S20cm uncertainty
48- 51 F4.1 arcsec amaj ? Major axis
53- 56 F4.1 arcsec amin ? Minor axis
58- 61 I4 arcsec2 Surf ? Surface when circular
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Note (1): Flag as follows:
a = Infrared counterpart 300758.
b = Infrared counterpart 284291.
c = Source 11 has a central compact source and an extended component.
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Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- SSTGC SST (Spitzer Space Telescope) Galactic
center (GC) number (1)
7- 9 A3 --- n_SSTGC [abc, ] Notes for individual sources (2)
11- 18 F8.4 deg GLON Galactic longitude
20- 27 F8.5 deg GLAT Galactic latitude
29- 33 F5.2 --- Chi2 χ2 value
35- 38 I4 --- Nfits Number of acceptably fitting models
40- 43 F4.1 mag Av Visual extinction Av
45- 48 F4.1 Msun Mass Average mass of the protostar
50- 52 F3.1 Msun e_Mass Mass uncertainty
54- 60 E7.2 Lsun Lum Average luminosity of the protostar
62- 68 E7.2 Lsun e_Lum Lum uncertainty
70- 76 E7.2 Msun/yr Menv Average mass accretion rate
78- 84 E7.2 Msun/yr e_Menv Menv 1σ standard deviation
86- 88 A3 --- Stage Evolutionary stage of the fitted source
(I, II or III)
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Note (1): Based on the IRAC catalogs (Ramirez et al. 2008, Cat. II/295;
in Simbad)
Note (2): Flag as follows:
a = radio counterpart 6
b = radio counterpart 5
c = Candidate YSO in the G359.43+0.02 cluster (table 2 of the paper; note
that "GLAT" for SSTGC 307175 in table 2 is not 0.02637 but, indeed,
-0.00026 as in table 3).
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Green source identification
(<[YHA2009] gNN> in Simbad) (1)
4- 10 F7.3 deg GLON Galactic longitude
12- 17 F6.3 deg GLAT Galactic latitude
19- 20 I2 h RAh Hour of right ascension (J2000)
22- 23 I2 min RAm Minute of right ascension (J2000)
25- 29 F5.2 s RAs Second of right ascension (J2000)
31 A1 --- DE- Sign of declination (J2000)
32- 33 I2 deg DEd Degree of declination (J2000)
35- 36 I2 arcmin DEm Arcminute of declination (J2000)
38- 41 F4.1 arcsec DEs Arcsecond of declination (J2000)
43- 69 A27 --- Comm Description
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Note (1): Visually identified from IRAC data. Many point sources may be
multiple or extended sources at higher resolution.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Source identification from table 5, or from
table8 when n_ID is 'a' (1)
3 A1 --- n_ID [a] Methanol class II maser source (2)
5- 13 F9.5 deg GLON Galactic longitude
15- 22 F8.5 deg GLAT Galactic latitude
24- 25 I2 h RAh Hour of right ascension (J2000)
27- 28 I2 min RAm Minute of right ascension (J2000)
30- 34 F5.2 s RAs Second of right ascension (J2000)
36 A1 --- DE- Sign of declination (J2000)
37- 38 I2 deg DEd Degree of declination (J2000)
40- 41 I2 arcmin DEm Arcminute of declination (J2000)
43- 46 F4.1 arcsec DEs Arcsecond of declination (J2000)
48- 52 I5 mJy Flux ? Flux
54- 58 F5.2 --- S/N ? Signal to noise ratio
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Note (1): Subset of 4.5um excess sources that were observed with MIPS at 70um.
Note (2): Source No. given is for table of methanol class II maser sources
(table 8).
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Byte-by-byte Description of file: table7.dat table8.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Source identification
4- 10 F7.3 deg GLON Galactic longitude
12- 17 F6.3 deg GLAT Galactic latitude
19- 20 I2 h RAh Hour of right ascension (J2000)
22- 23 I2 min RAm Minute of right ascension (J2000)
25- 29 F5.2 s RAs Second of right ascension (J2000)
31 A1 --- DE- Sign of declination (J2000)
32- 33 I2 deg DEd Degree of declination (J2000)
35- 36 I2 arcmin DEm Arcminute of declination (J2000)
38- 41 F4.1 arcsec DEs Arcsecond of declination (J2000)
43- 47 F5.1 km/s Vlsr LSR velocity
49- 55 A7 --- Ref Reference(s) (1)
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Note (1): References as follows:
H90 = Haschick et al. 1990ApJ...354..556H 1990ApJ...354..556H (44GHz);
S94 = Slysh et al. 1994MNRAS.268..464S 1994MNRAS.268..464S (44GHz);
M97 = Mehringer & Menten 1997ApJ...474..346M 1997ApJ...474..346M (44GHz, multiple sources in
Sgr B2);
V00 = Val'tts et al. 2000MNRAS.317..315V 2000MNRAS.317..315V (95GHz).
C96 = Caswell 1996MNRAS.283..606C 1996MNRAS.283..606C;
W98 = Walsh et al. 1998, Cat. J/MNRAS/301/640
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Byte-by-byte Description of file: table9.dat table10.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [YHA2009] Green number (gNNA)
6- 12 I7 --- SSTGC SSTGC number
14- 21 F8.4 deg GLON Galactic longitude
23- 29 F7.4 deg GLAT Galactic latitude
31- 35 F5.2 --- Chi2 χ2 value
37- 40 I4 --- Nfits Number of acceptably fitting models
42- 45 F4.1 mag Av Visual extinction Av
47- 50 F4.1 Msun Mass Average mass of the protostar
52- 54 F3.1 Msun e_Mass Mass uncertainty
56- 62 E7.2 Lsun Lum Average luminosity of the protostar
64- 70 E7.2 Lsun e_Lum Lum uncertainty
72- 78 E7.2 Msun/yr Menv Average mass accretion rate
80- 86 E7.2 Msun/yr e_Menv Menv 1σ standard deviation
88- 90 A3 --- Stage Evolutionary stage of the fitted source
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 26-Sep-2011