1. The ALMA view of a Carbon Rich AGB Star: The Spectrum of IRC+10216
J. Cernicharo, M. Agúndez, F. Daniel, A. Castro-Carrizo, N. Marcelino, C. Joblin, M. Guélin, J. Goicoechea
J. Cernicharo, ICMM, Group of Molecular Astrophysics,

2. IRC+10216 observed at all wavelengths with single dishes
Brightest mid-IR source in the sky. Nearest C-rich AGB star
Sensitive Millimeter Line surveys (rms below a few mK)
(2mm = Cernicharo et al., 2000, A&A SS, 142, 181)
(3mm = Cernicharo et al., 2014, A&A)
(1mm = ongoing) ( GHz line survey with HIFI; Cernicharo et al., 2010)
High spectral resolution Infrared line surveys (TEXES)
14  m region (C2H2, HCN & SiS) Fonfría et al., 2008, ApJ
50% of ISM molecules detected in this source (polar molecules):
Metal-bearing : NaCl, KCl, AlCl, AlF, MgNC, MgCN, AlCN, SiNC, SiCN, KCN,
NaCN, FeCN,…
Carbon chains: CCH, C3H, C4H, C5H, C6H, C7H, C8H, CN, C3N, C5N, HCN,
HCCN, HC3N, HC4N, HC5N, HC7N, HC9N
Silicon-bearing species: SiO, SiS, SiC, SiC2, SiC3, SiC4
Sulphur-bearing species: CS, CCS, CCCS, C5S
Phosphorus-bearing species: PN, CP, HCP, CCP, PH3
Anions: CN-, C3N-, C5N-, C4H-, C6H-, C8H-
Nanocosmos Yebes – 06/2/2014

3. IRC+10216 CO J=2-1 30m Data Extreme Outer Shells Outer carbon radicals
Star radius is 0.02”. CO envelope radius >200”
IRC+10216
CO J=2-1
30m
Data
Cernicharo et al. 2014
Extreme
Outer
Shells
Outer carbon
radicals
Shell (r=14”)
Inner
Refractory
Species.
Dust
Formation
Zone (<1”)

4. Inner shells Outer shells
Very poorly known region
Por último, la envoltura circunestelar posee una elevada riqueza de moléculas.
En este esquema se representa la estructura de una envoltura circunestelar típica, la cual se extiende desde la superficie de la gigante roja (con temperaturas de K y densidades de 1e15 cm-3) hasta una distancia de hasta 1 año luz (en donde la temperatura es de unos cuantos grados Kelvin y la densidad es de unas pocas partículas por cm3).
En las regiones más cercanas a la fotosfera el gas es denso y caliente y la composición viene en gran medida dada por el equilibrio químico, esto es se forman moléculas estables (CO, H2O, SiO en estrellas ricas en oxigeno y CO, C2H2, y HCN en envoltura ricas en carbono).
La composición química puede verse alterada por procesos como ondas de choque asociadas a la pulsación de la estrella (las estrellas AGB son estrellas variables), y a la formación del polvo, la cual ocurre a partir de 5-20 R* cuando la temperatura cae por debajo de unos 1000 K.
En la envoltura externa las moléculas comienzan a estar expuestas al campo de radiación UV del ISM y son fotodisociadas, lo que da lugar a una fotoquímica en que los radicales formados intervienen en reacciones químicas rápidas y dan lugar a nuevas especies químicas. Esta química es particularmente rica en envolturas ricas en carbono.

5. The spectrum of IRC+10216 is rather well known
The spectrum of IRC is rather well known. We are able to identify all
isotopologues and vibrationally excited states of abundant species with
single dishes and interferometers at 3 and 2 mm and in the line survey with
HIFI/Herschel.
Line survey at l = 3 mm carried out with the IRAM 30-m radio
telescope:
GHz
emission lines (~37 lines/GHz)
- 886 assigned to rotational transitions of 60 molecules
(+ different isotopoloques and vibrationally excited states)
- 453 unassigned lines (only 31 with TA* > 10 mK) –before anions-
- high sensitivity: rms(TA*) < 1 mK for most frequencies
Nanocosmos Yebes – 06/2/2014
Rest Frequency (GHz)

6. LINE SURVEYS
Esta figura recoge el conjunto de datos de que disponemos sobre IRC Consiste en el espectro a longitudes de onda milimétricas (desde 80 a 280 GHz) tal y como ha sido obtenido con el telescopio IRAM 30-m.
El espectro consiste en líneas en emisión

7.  que corresponden a transiciones de rotación de diversas moléculas.
Cernicharo et al. 2000
Cernicharo et al. en preparación
 que corresponden a transiciones de rotación de diversas moléculas.
Como se puede apreciar se ha cubierto prácticamente todo el rango espectral accesible con este telescopio ( GHz). Los receptores actuales operan hasta 360 GHz y seguramente merecería la pena investigar este rango espectral en un futuro próximo.
La banda de 1.3 mm es un composite de varias observaciones llevadas a cabo en los últimos 10 años.
El barrido espectral a 2 mm se encuentra publicado en Cernicharo et al
Por su parte, el barrido espectral a 3 mm se encuentra actualmente en preparación para ser publicado y constituye la parte más novedosa.

8. Cernicharo et al., 2010, A&A, 521, L8

9. HCN
NH3 CN
HC3N
C3N
HC5N
HNC
CH3CN
HC7N
HC9N
CH2CN
HC2N
C5N
HCCNC
C2H3CN
C5N-
HC4N
C3N-
HNCCC CO
H2O OH
H2CO
C3O
HCO+
C2H2
CH4
C2H
C4H C2 C3 C5
l-C3H
C6H
C5H
c-C3H2
CH3C2H
c-C3H
C2H4
H2C4
C8H
C7H
H2C6
C6H-
C8H-
H2C3
C4H-
10-3
10-4
10-5
10-6
10-7
10-8
10-9
10-10
1(-3)
1(-7)
4(-8)
1.3(-8)
2(-9)
7(-10)
8(-5)
3.5(-6)
3(-6)
2.5(-6)
1(-6)
5(-8)
3(-8)
2(-8)
1.4(-8)
8(-9)
3(-9)
1.5(-9)
3(-10)
2(-5)
2(-6)
1.7(-6)
1.4(-6)
4(-7)
2(-7)
7(-9)
6(-9)
4(-9)
2.3(-9)
1.1(-9)
5(-10) CS
C2S
C3S
H2CS
H2S
C5S
5(-7)
1.2(-8)
1.2(-9)
SiC2
SiS
SiH4
SiO
SiC
SiN
c-SiC3
SiC4
SiCN
SiNC
1.2(-6)
2.2(-7)
1.2(-7)
HCP CP
PH3 PN
C2P
2.5(-8)
1(-8)
1(-9)
AlCl
NaCN
MgNC
AlF
NaCl
AlNC
MgCN
KCl
3.5(-8)
7.5(-9)
2.5(-10)

10. ALMA observations in Cycle 0 between 255-275 GHz
Four frequency settings with 2 hours of observing time
Good UV coverage even with 16 antennas
However, serious problems with the data, wrong frequency
scale, selfcalibration absolutely necessary to reach the
sensitivity goals
Cycle 1 observations between GHz expected next
months
Cycle 2 full 3mm line survey also expected soon

11. The ALMA view of IRC+10216: A forest of U Lines
HCN in high energy
vibrational levels
(>10000 K)
SiC2 in v3 and 2v3,…
SiS up to v=10
(& isotopologues)
SiO up to v=3
HNC in vibrational
levels up to 6000 K
+ hundreds of U lines
Cernicharo et al., 2013
ApJ Letters, 778, L25

12. Plenty of unknown narrow features!!!
IRC as view by ALMA
Plenty of unknown narrow features!!!
Cernicharo et al., 2013, ApJ, 778, L25
See also Patel et al. 2010, for narrow U-lines at 350 GHz with the SMA
Cernicharo et al., 2011, A&A, for narrow lines from HCN v#0

13. Looking for known species coming ONLY from the dust formation zone.
HNC and HCN. Deriving physical conditions
Observed (black curves) and modeled (red) line profile of the J =3-2 in vibrationally excited states of HNC as observed with ALMA
near ∼270 GHz. The blue and green curves show the corresponding ν2 lines of HCN (blue) and H13CN (green) observed in the
same setup, scaled down by factors of 50 and 6 respectively. HNC frequencies (in MHz) and upper level energies (in kelvins) are
given at the top of each box (Cernicharo et al., 2013, submitted to ApJ Letters)

14. Physical parameters
HNC abundance profile
HNC vibrationally excited traces the region
1-3 R*, i.e., the dust nucleation zone.
Mergin HNC and HCN vibrationally excited
data will provide a detailed analysis of the
1-20 R* zone.

15. ALMA
from
the star
to the ISM
The physics
and the
chemistry
from the dust
formation
zone

16. We have used our own catalogs (MADEX) in addition to CDMS & JPL
to try to identify all these U-lines without success.
MADEX is very well adapted to the study of the molecular content
of IRC (4950 species with spectroscopic accuracy).
No clear identification for all these lines yet. Probably species formed in
the dust formation zone, participating in the nucleation of dust seeds
and dust growth. Silicon-bearing clusters, carbon-clusters,
and metal-bearing species that disappear after a few stellar radii.
J=0 l-doubling transitions of the vibrational levels of HCN involving v2.
ALMA observations of evolved stars will require a huge effort from
the molecular spectroscopy community to characterize the gas
composition in the dust formation zone.
Even Cycle 0 observations produce spectacular images of the innermost
regions of the envelope of CW Leo (IRC+10216). Mass loss history.

17. Thank you very much for your attention