2017A&A...597A..44B


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.03CET11:22:18

2017A&A...597A..44B - Astronomy and Astrophysics, volume 597A, 44-44 (2017/1-1)

Dense gas in low-metallicity galaxies.

BRAINE J., SHIMAJIRI Y., ANDRE P., BONTEMPS S., GAO Y., CHEN H. and KRAMER C.

Abstract (from CDS):

Stars form out of the densest parts of molecular clouds. Far-IR emission can be used to estimate the star formation rate (SFR) and high dipole moment molecules, typically HCN, trace the dense gas. A strong correlation exists between HCN and far-IR emission, with the ratio being nearly constant, over a large range of physical scales. A few recent observations have found HCN to be weak with respect to the far-IR and CO in subsolar metallicity (low-Z) objects. We present observations of the Local Group galaxies M 33, IC 10, and NGC 6822 with the IRAM 30 m and NRO 45 m telescopes, greatly improving the sample of low-Z galaxies observed. HCN, HCO+, CS, C2H, and HNC have been detected. Compared to solar metallicity galaxies, the nitrogen-bearing species are weak (HCN, HNC) or not detected (CN, HNCO, N2H+) relative to far-IR or CO emission. HCO+ and C2H emission is normal with respect to CO and far-IR. While 13CO is the usual factor 10 weaker than 12CO, C18O emission was not detected down to very low levels. Including earlier data, we find that the HCN/HCO+ ratio varies with metallicity (O/H) and attribute this to the sharply decreasing nitrogen abundance. The dense gas fraction, traced by the HCN/CO and HCO+/CO ratios, follows the SFR but in the low-Z objects the HCO+ is much easier to measure. Combined with larger and smaller scale measurements, the HCO+ line appears to be an excellent tracer of dense gas and varies linearly with the SFR for both low and high metallicities.

Abstract Copyright: © ESO, 2016

Journal keyword(s): galaxies: individual: M 33 - galaxies: individual: IC 10 - galaxies: individual: NGC 6822 - Local Group - galaxies: ISM - stars: formation

Simbad objects: 28

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Number of rows : 28

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 [LBW2006] B8 MoC 00 20 21.60 +59 17 08.8           ~ 3 0
2 [LBW2006] B9 MoC 00 20 22.90 +59 21 18.3           ~ 3 0
3 IC 10 G 00 20 23.16 +59 17 34.7   13.6 9.5     ~ 1022 0
4 [LBW2006] B11 MoC 00 20 27.70 +59 16 59.4           ~ 4 0
5 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11211 1
6 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9702 1
7 IRC +30021 Mi* 01 11 15.9342978462 +30 38 06.242372347       13.73   M10 75 0
8 [BKG2013] M33no6 MoC 01 33 33.770 +30 32 15.64           ~ 2 0
9 [EPR2003] 23 MoC 01 33 45.1 +30 36 00           ~ 6 0
10 M 33 GiG 01 33 50.904 +30 39 35.79 6.17 6.27 5.72     ~ 5249 1
11 [BLR2008] M33 14 MoC 01 33 52.4 +30 39 19           ~ 13 0
12 [BKG2013] M33no3 MoC 01 34 07.000 +30 43 02.00           ~ 2 0
13 [EPR2003] 1 MoC 01 34 09.3 +30 49 06           ~ 15 0
14 [BKG2013] M33no1 MoC 01 34 16.400 +30 49 06.00           ~ 2 0
15 [BKG2013] M33no2 MoC 01 34 21.770 +30 57 04.99           ~ 2 0
16 NGC 604 HII 01 34 32.1 +30 47 01           ~ 554 0
17 [CG99b] NGC 604 C Rad 01 34 32.33 +30 46 58.0           ~ 6 0
18 [CG99b] NGC 604 A Rad 01 34 33.41 +30 46 57.3           ~ 7 0
19 [CG99b] NGC 604 B Rad 01 34 33.44 +30 46 50.3           ~ 6 0
20 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5863 1
21 IC 342 SBG 03 46 48.514 +68 05 45.98   10.5       ~ 1406 1
22 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15206 1
23 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 2049 1
24 M 51 GiP 13 29 52.698 +47 11 42.93   9.26 8.36 8.40   ~ 3890 4
25 M 10 GlC 16 57 09.05 -04 06 01.1     4.98     ~ 706 0
26 [H25] V HII 19 44 52.84 -14 43 09.8           ~ 59 0
27 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1452 0
28 NAME Local Group GrG ~ ~           ~ 7184 0

    Equat.    Gal    SGal    Ecl

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2021.03.03-11:22:18

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