140 likes | 282 Views
[OI] and [NII] Observations of Relevance to STO. Gordon Stacey. 3 P 2. 188 K. N +. 3 P 1. 70 K. 0 K. 3 P 0. [NII] Lines. Density tracer for low density ionized gas Proxy for Lyman continuum flux Determines [CII] fraction from ionized gas [NII] has two transitions
E N D
[OI] and [NII] Observations of Relevance to STO Gordon Stacey
3P2 188 K N+ 3P1 70 K 0 K 3P0 [NII] Lines • Density tracer for low density ionized gas • Proxy for Lyman continuum flux • Determines [CII] fraction from ionized gas • [NII] has two transitions • Both these lines relatively unexplored • 122 m line somewhat challenging from airplane • 205 m line at long wavelength end of photoconductors • Lines are strong – fair number of ISO LWS observations of 122 m line • 2 KAO observations using the CGS of both lines (M82 and G333.6-0.2) • Large beam COBE observations of 205 m line • Ground based 205 m line observations 122 um 205 um
3P0 327 K O0 3P1 228 K 0 K 3P2 [OI] Lines • Many observations of these lines from Galactic and extra-galactic sources • KAO/ISO LWS • Very strong lines in general • [OI]/[CII] typically ½ • [OI] 63/146 ~ 15-20:1 146 um 63 um
COBE • Large (7.2) beam • What is the scale height? • PDR or ionized gas • [CII]/[NII] 205 ~ 10:1 • [CII]/[NII] 122 ~ 6:1 • Argue for 27% of [CII] from ionized gas
[NII] 205 m Line: Carina Nebula • [NII] 205 m line from in the Carina Nebula with SPIFI on AST/RO at South Pole (Oberst et al. 2006) • [NII] 122/205 m line ratio ~ 1.8: 1 ne ~ 30 cm-3 • [CII]/[NII] ratio ~ 9:1, predicted ratio ~ 2.4:1 27% of [CII] originates from ionized gas
Observations of Candidate Sources • M17 KAO: Meixner et al. 1992 • Peak ~ 1.310-3erg/s/cm2/sr • Beam ~ 36” • ISO: Henning et al. 1998 A&A 332, 1035 • Just one spectrum presented • [OI] and [NII] lines detected
Other Candidates • MBM12 – nearby starformation region • Haven’t found much yet – Mark Wolfire found [CII] • Polaris Flare • Again, haven’t found much ISO data yet • Carina Nebula • SPIFI-AST/RO map of [NII] over > 10’ square region with 55” beam • ISO [NII] 122 m, [OI] and [CII] data available and published (Mizutani et al. 2002, 2004)
DR21 in Cygnus • KAO [OI] 63 m line obtained over inner 2.5’ (Poglitsch et al. 1996) – 25” beam • ISO LWS spectroscopy available and published in Jakob et al. 2007 including [NII] and [OI] lines
Galactic Plane Surveys • Not really any dedicated surveys in [OI] or [NII] save COBE FIRAS • However there has been work on the ISO data set – collecting all the observations
ISO Study of the Diffuse ISM • Searched the ISO archive and find there are about 500 LO1 spectra of Galactic LOS w/o known energetic sources • LWS01: 47 to 196 m • [OI] 63 and 145 m • [CII] 158 m • [NII] 122 m • Current study contains 144 LOS w/ l <10
Inner Outer 100 um continuum flux (33 Jy) Galactic Center Galactic Longitude (abs. value) Three Regions Defined
Dust color temperature • Plot is 100/160 vs. 62.5/100 continuum ratios • Tracks are grey body temps for = 0 an 1.5 • Shift below = 0 is likely due to hot small grain contribution at 63.5 m (40% in inner galaxy and 60% in outer galaxy • Color temps and need to be corrected for this effect
Atomic Fine Structure Lines • Excellent correlation between the line intensities and far-IR continuum
Larger PDR contribution in brighter regions Not much (1/6) [CII] from ionized gas Optically thick or forground absorbed 63 m line Line Ratios • Low continuum (33 Jy/beam) • [CII]/[NII] ~ 3.6:1 • [OI](63)/[CII] ~ 1:3 • [OI](63)/[OI] 146 ~ 15:1 • High continuum (3300 Jy/beam) • [CII]/[NII] ~ 13:1 • [OI](63)/[CII] ~ 1:2.5 • [OI](63)/[OI] 146 ~ 8.5:1