stellar evolution in the post-agb stage
DESCRIPTION
Or... “An optical catalogue of post-AGB candidates”. Stellar evolution in the post-AGB stage. Olga Suárez Laboratorio de Astrofísica Espacial y Física Fundamental – Madrid (Spain). Supervisors: Minia Manteiga Outeiro Pedro García Lario. - PowerPoint PPT PresentationTRANSCRIPT
Stellar evolution in the post-AGB stage Olga Suárez
Laboratorio de Astrofísica Espacial y Física Fundamental – Madrid (Spain)
Supervisors: Minia Manteiga Outeiro
Pedro García Lario
Or... “An optical catalogue of post-AGB candidates”
In colaboration with: Arturo Manchado, Ana Ulla, S.R. Pottasch
Objectives
Study of stars in the transition phase from AGB to PN.
Catalogue - large number of objects
Multiwavelength study - SEDs
Use of statistical tools
Objectives
Study of stars in the transition phase from AGB to PN.
Catalogue - large number of objects
Multiwavelength study - SEDs
Use of statistical tools
Stellar evolution
Post-AGB evolution
(Blöcker, 1995)
Nomenclature used in this work
Post-AGB: AGB mass loss has ceased. not ionized envelope
Transition objects: stellar continuum forbidden lines (no [OIII])
Planetary Nebula (PN): no stellar continuum forbidden lines
The catalogue - Selection criteria
IRAS colours:
[12] – [25] = 2.5 log (F12m/F25m)
[25] – [60] = 2.5 log (F25m /F60m)
Flux ratios: F12m /F25m 0.50
F25m /F60m 0.35
F60m /F100m 0.60
Low IRAS variability to avoid AGBs
The catalogue in the IRAS c-c diagram
The catalogue - spectroscopic observations
Telescope DatesResolution
(A/ pix)SpectralRange (A)
3.6 m ESO March 1988 3.79 3406-69751.5 m ESO J an. 1989 2.47 4272-68121.5 m ESO Feb. 1989 2.80 4046-69201.5 m ESO J une 1990 3.47 4050-6925
2.5 m INT May 1991 2.813570-52265538-7240
2.2 m CAHA Nov. 1991 2.50 3830-67361.5 m ESO Aug. 1992 2.83 3590-94251.5 m ESO March 1993 3.74 3321-110152.5 m INT J uly 1993 1.48 5376-72691.5 m ESO March 1994 3.74 3285-10980
2.5 m INT Aug. 1994 1.573779-54015570-7195
1.5 m ESO Feb. 1995 3.79 3532-11190
2.5 m INT J une 1995 1.573700-54555488-7255
2.5 m INT Apr. 2001 3.30 3702-74013.6 m ESO J une 2003 5.30 3600-9200
The catalogue - imaging observations
Telescope Dates
3.6 m ESO J une 1990 J KT (La Palma) J uly 1990 0.9 m Dutch March 1994 2.5 m NOT J une 2000 2.5 m NOT May 2001 3.6 m ESO J une 2003
The catalogue - the search
Hα - cont Hα
The catalogue - the search
The catalogue - the search
IRAS 17395-0841
[NII]Hα
Hα
Riera et al., RevMexAA, 2003
Suárez et al., in preparation
The catalogue - number of objects
255 observed objects
104 post-AGB stars (with optical spectra)
21 transition objects
36 Planetary Nebulae
3 AGB stars
38 young stellar objects or HII regions
2 Seyfert galaxies
5 peculiar stars
47 objects without optical counterpart (42 believed to be obscured post-AGB stars)
The catalogue - a sample
The catalogue - a sample
Analysis of the spectra
Spectral classification of post-AGB stars and young stellar objects.
Comparison with catalogues (Silva, 1992; Pickles, 1998; Jacoby, 1984)
Wavelength
Rel
ativ
e fl
ux
Analysis of the spectra Excitation classes for PNe (Morgan, 1984;
Dopita, 1990; and Crowther, 1998) Based on strength line ratios.
Analysis of the spectra
Spectral Energy Distributions Data from optical spectra, 2MASS, MSX, IRAS. Classification according to van der Veen et al. (1989)
Class I Class II Class III
Class IVa Class IVb
IRAS colour-colour diagram
Models by van Hoof et al. (1997), based on Blöcker (1995), show the evolution in this diagram.
IRAS colour-colour diagram
Conclusions
Observations - selection criteria based on IRAS colours
Catalogue - 255 sources: 104 post-AGB stars, 21 transition objects, 36 PNe.
Spectra and SEDs classified - multiwavelength analysis using statistical tools
Galactic latitude distribution
Statistical indicator of the mass of a population of stars.
High latitude (wide galactic latitude distribution) lower mean mass
Low latitude (narrow galactic latitude distribution) higher mean mass
Results Evolutionary status + Galactic latitude + statistics
Objects without optical counterpart are obscured post-AGB stars similar to those not observed
Post-AGB stars and PNe have different galactic latitude
distributionfrom obscured post-AGB stars
Conclusions
Observations - selection criteria based on IRAS colours
Catalogue - 255 sources: 104 post-AGB stars, 21 transition objects, 36 PNe.
Spectra and SEDs classified - multiwavelength analysis using statistical tools