pedro garcia-larioplanetary nebulae beyond the milky way 19-21/05/2004, page 1 extragalactic pne:...

Pedro GARCIA-LARIOPlanetary Nebulae beyond the Milky Way 19-21/05/2004,

Extragalactic PNe: methods of Extragalactic PNe: methods of discovery using infrared photometrydiscovery using infrared photometry

ESA/ISO Data Centre, VILSPA Madrid, Spain

Pedro García-Lario, Amelia Bayo & Carlos Alfageme


1. A bit of history

2. The IRAS revolution

3. The ISO’s view

4. PNe in the near-infrared

5. PNe as seen by MSX and 2MASS

6. Extrapolation to other galaxies

7. The future

8. Conclusions

Outline


– PNe are known to be strong infrared emitters since the 1960’s

- First detection of an infrared excess at 10 microns in NGC 7027 (Gillet et al. 1967)

- IRC Catalogue @ 2.2 microns (first all-sky survey) shows infrared excess in red Miras, some of them invisible in the optical!

(Neugebauer & Leighton 1969)

- Detection of double-peaked OH maser emission at 1612 MHz in optically invisible Miras (‘OH/IR stars), identified as precursors of planetary nebulae (Wilson & Barrett 1968)

- AFGL catalogue (all-sky survey at 4.2, 11.0, 19.8, and 27.4 microns) (Price & Walker 1976)

- Ground-based mid-infrared (8-20 microns) observations of planetary nebulae (Cohen & Barlow 1974, 1980)

- Airborne stratospheric observatories like KAO (several flights since 1976 observing in the range 37-110 microns) (Moseley 1980)

A bit of history


– All-sky survey in four broad photometric bands centred at 12, 25, 60 and 100 microns, launched in 1983 (250,000 sources in the IRAS Point Source Catalogue)

- F > 0.5 Jy at 12, 25 and 60 microns;

- F > 1.5 Jy at 100 microns;

- poor spatial resolution; confusion close to the GC

– Additional spectra (LRS) in the range 7.7-13.4 + 11.0-22.6 microns of the strongest sources (5425 sources automatically extracted)

- F>10 Jy at 12 microns; - 90% completeness for F> 28 Jy at 12 microns- R ~ 20-60

The IRAS revolution


The IRAS revolution

(Van der Veen & Habing 1989)

Region V

is mostly

populated

by PNe


– AGB stars follow a well-defined sequence in the IRAS [12]-[25] vs. [25]-[60] colour-colour diagram in their way to become planetary nebulae

(van der Veen & Habing 1989)

– Strong differences as a function of the dominant chemistry in the circumstellar shell (carbon-rich vs. oxygen-rich)

– Planetary nebulae show characteristic infrared colours, corresponding to dust temperatures of 100-150 K (Pottasch et al. 1988)

– First systematic searches for new planetary nebulae based on IRAS photometry (Preite-Martinez 1988; Garcia-Lario 1992)

The IRAS revolution


The IRAS revolution

Pottasch et al. (1988)


– The GLMP Catalogue of IRAS sources with colours like Planetary Nebulae (Garcia-Lario et al. 1997)

– Selection criteria:• FQUAL 3 at 25 and 60 microns; FQUAL 2 at 12 microns

• F (12) / F (25) 0.50

• F (25) / F (60) 0.35

• If FQUAL (100 microns) 2 ; F (60) / F (100) 0.60

– 1084 sources; 47% previously identified in the literature• 50% were PNe

• 27% were OH/IR stars or post-AGB stars

• A small contamination from YSO’s, Ultra-compact HII regions, Vega-like stars and Seyfert galaxies (in total less than 24%)

The IRAS revolution


The IRAS revolution

Garcia-Lario et al. (1997)

Distribution

of identified

sources in the

GLMP catalogue


The IRAS revolution


Distribution of

newly classified

sources in the

GLMP catalogue

Mainly precursors!


– IRAS colours are a very efficient way to search for planetary nebulae candidates

but….– Strong bias towards young planetary nebulae and

precursors

– Open questions:• How to distinguish planetary nebulae from their precursors?• Can JHK near-infrared photometry help?• Can these or similar criteria be applicable to other infrared

surveys?

The IRAS revolution


–

The ISO’s view

–SWS + LWS (2-200 microns)

–Relative contribution of:

Dust thermal emission

Nebular emission lines

Solid state features

–Two well-defined evolutionary

sequences as a function of the

dominant chemistry in the shell

C-rich O-rich


–

The ISO’s view

C-rich PN (young)


–

The ISO’s view

O-rich PN (old)


PNe in the near-infrared


Many PNe show a

characteristic excess

in the J-band !

J-H > 0.2

H-K >0.4

Useful to search for

intermediate

excitation PNe


– Mid-Course Space Experiment (MSX), launched in 1999

– Galactic plane (|b| 6 degrees) survey at 4 main photometric bands centred at 8, 11, 14 and 21 microns (A,C,D and E bands)

- Similar sensitivity to IRAS 12 and 25 micron bands

- better spatial resolution; less confusion

- good to detect GC PNe?

– Plus a few high galactic latitude areas including the LMC, the SMC and a few nearby galaxies of the Local Group

– MSX Point Source Catalogue v6 contains more than 400,000 sources (how many of them new PNe?)

– Can we use a similar approach to the one used for IRAS in order to search for new PN candidates?

PNe as seen by MSX


Galactic PNe as seen by MSX

32,409 sources with good

quality MSX photometry in

A,C and D bands

90% of them with no

Identification in SIMBAD



Only 10% (3,278 sources) of

them were well identified in

SIMBAD

155 sources identified as

PNe or Post-AGB stars

(~4.7% of the identified

sources)



PNe and Post-AGB stars

strongly concentrated in region

defined by:

[A] - [C] 0.7

[C] – [D] 0.7

Populated by 1,372 sources

400 sources well identified

(~40% PNe or Post-AGB stars)

972 sources not identified

Strong contamination by YSO’s


– s


15,068 sources with good quality

MSX photometry in A,C,D and E

bands

Normal stars are eliminated

by considering only good quality

detections in the E` band


– s


Again, stronger concentration of

PNe and Post-AGB stars in

region defined by:

[A] - [C] 0.7

[C] – [D] 0.7

Populated by 1,042 sources

But still not enough; only ~40% of

PNe and Post-AGB stars among

the 312 well identified sources in this

group.

Strong contamination by YSO’s



An additional selection criterium

to avoid YSO’s: |b| 2 degrees

9,884 sources well detected in

A,C and D bands

1,304 sources well identified

922 (71%) AGB stars

284 (22%) Stars

67 (5%) PN/PAGB

26 (2%) YSO’s

5 (<1%) Galaxies



Adding the selection criteria:

[A]-[C] 0.7

[C]-[D] 0.7

Only 67 sources well identified

16 AGB stars

1 Star

45 PN/PAGB (~69%)

3 YSO’s

2 Galaxies

Large majority of PNe!



An additional selection criterium

to avoid YSO’s: |b| 2 degrees

4,305 sources well detected in

A,C,D and E bands

764 sources well identified

616 (80%) AGB stars

61 (8%) Stars

61 (8%) PN/PAGB

21 (<3%) YSO’s

5 (~1%) Galaxies



Adding the selection criteria:

[A]-[C] 0.7

[C]-[D] 0.7

Only 66 sources well identified

15 AGB stars

1 Star

45 PN/PAGB (~69%)

3 YSO’s

2 Galaxies

Large majority of PNe!



We can do the same with other

MSX colour-colour diagrams

Using the [A] – [C] vs. [D] – [E]

diagram we obtain very similar

results



Again, PN/Post-AGB stars are

strongly concentrated in a well

defined region of the diagram

Can a similar analysis be done

on extragalactic sources

detected by MSX?


Extragalatic PNe as seen by MSX

Some good candidates

found in the LMC

Some are well known

LMC Pne

Others will need

follow-up observations


Extragalactic PNe as seen by MSX

Only a few in the SMC



su

Number of sources need

to be substantially

increased

Use of not so good

quality observations?



Use of other MSX

colour-colour diagrams

give very similar results,

as for the galactic PNe


- All-sky ground-based near-infrared survey (JHK photometry for ~470 million entries in the Point Source Catalogue)

- Selection criteria:• J < 14.0 mag• Good quality (AAA) in all three bands• J – H < 0.2• H – K > 0.4• No confusion flags (to avoid binary systems formed by cool+hot star)

- Only 535 2MASS sources satisfy the above criteria- 73 of them were also detected by MSX and 26 have the right colours

expected for a PN ! Some of them are well known PNe. Follow-up observations needed for the rest

- Extend this search to fainter sources and to the Magellanic Clouds

..and what about 2MASS?


– ASTRO-F survey (launch in August 2005)• All-sky survey at 50-110 microns (several narrow and broad bands

in this wavelength range) as main goal (sensitivity ~0.1 Jy)

• Possibly complemented with a mid-IR all-sky survey at 9 and 19 microns (sensitivity of 40 mJy and 80 mJy, respectively) still under study

• Deeper observations of some high galactic latitude regions, including the Magellanic Clouds

– Dedicated observations using specific filters with:• VISIR@VLT• Spitzer Space Telescope

– In a more distant future…• JWST, Spica, …

The (near) future


– Infrared colour-colour diagrams are a powerful tool to search for PNe and their immediate precursors in the Galaxy

– Better sensitivity and higher spatial resolution will soon allow the application of similar colour criteria to search for planetary nebulae in nearby galaxies

– Multi-wavelength observations covering the whole infrared spectral range are desirable. In some cases, follow-up observations in other spectral ranges will still be necessary to confirm candidate sources.

Conclusions

pedro garcia-larioplanetary nebulae beyond the milky way 19-21/05/2004, page 1 extragalactic pne:...

Documents