J/A+A/549/A27 M31 CO(2-1) spectra (Melchior+, 2013)
A cold-gas reservoir to fuel the M31 nuclear black hole and stellar cluster.
Melchior A.-L., Combes F.
<Astron. Astrophys. 549, A27 (2013)>
=2013A&A...549A..27M 2013A&A...549A..27M
ADC_Keywords: Planetary nebulae ; Carbon monoxide ; Radial velocities ;
Galaxies, spectra
Keywords: Galaxies: individual - galaxies: nuclei -
galaxies: kinematics and dynamics - Galaxies: bulges - galaxies: ISM -
ISM: planetary nebulae: general
Abstract:
With IRAM-30m/HERA, we have detected CO(2-1) gas complexes within
30arcsec (100pc) from the center of M31 that amount to a minimum total
mass of 4.2x104M☉ (one third of the positions are detected).
Averaging the whole HERA field, we show that there is no additional
undetected diffuse component. Moreover, the gas detection is
associated with gas lying on the far side of the M31 center as no
extinction is observed in the optical, but some emission is present on
infrared Spitzer maps. The kinematics is complex. (1) The velocity
pattern is mainly redshifted: the dynamical center of the gas differs
from the black hole position and the maximum of optical emission, and
only the redshifted side is seen in our data. (2) Several velocity
components are detected in some lines of sight.
Our interpretation is supported by the reanalysis of the effect of
dust on a complete planetary nebula sample. Two dust components are
detected with respective position angles of 37deg and -66deg. This
is compatible with a scenario where the superposition of the
(PA=37deg) disk is dominated by the 10kpc ring and the inner 0.7kpc
ring detected in infrared data, whose position angle (-66deg) we
measured for the first time. The large-scale disk, which dominates the
HI data, is steeply inclined (i=77deg), warped and superposed on the
line of sight on the less inclined inner ring. The detected CO
emission might come from both components.
Description:
36 reduced spectra obtained at IRAM-30m are provided in ascii format.
They are presented in Figure 1 of the article.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
00 42 44.33 +41 16 07.5 M31 = UGC 454
-----------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
m31-1aof.dat 24 36 Offset of each spectrum
sp/* . 36 Individual spectra
--------------------------------------------------------------------------------
Byte-by-byte Description of file: m31-1aof.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 3 I2 --- Nsp Spectrum number
5- 7 I3 arcsec offX X offset (1)
9- 11 I3 arcsec offY Y offset (1)
13- 24 A12 --- FileName Name of spectrum file in subdirectory sp
--------------------------------------------------------------------------------
Note (1): the offsets are computed with respect to the center of M31
00:42:44.37+41:16:08.34 (J2000)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: sp/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 km/s Vlsr LSR Velocity
8- 19 F12.8 K Tmb Main beam temperature
--------------------------------------------------------------------------------
Acknowledgements:
Anne-Laure Melchior, A.L.Melchior(at)obspm.fr
History:
* 11-Dec-2012: on-line version
* 28-May-2018: corrected spectra 22, 23, 24 and 26 (from author)
(End) Anne-Laure Melchior [LERMA, France], Patricia Vannier [CDS] 15-Nov-2012