new deuterium and 3-helium abundance determinations for the galactic ism
DESCRIPTION
TOM BANIA Institute for Astrophysical Research Department of Astronomy Boston University. New Deuterium and 3-Helium Abundance Determinations for the Galactic ISM. Light Elements as Baryometers. The 327 MHz Deuterium Line. Rogers, Dudevoir, Carter, Fanous, Kratzenberg, and Bania - PowerPoint PPT PresentationTRANSCRIPT
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New Deuterium and 3-HeliumAbundance Determinations
for the Galactic ISM
TOM BANIAInstitute for Astrophysical Research
Department of Astronomy
Boston University
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Light Elements as Baryometers
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The 327 MHz Deuterium Line
Rogers, Dudevoir, Carter, Fanous, Kratzenberg, and Bania2005, ApJ, 630, L41-44 (RDCFKB):
“Deuterium Abundance in the Interstellar Gas of the Galactic Anticenter from the 327 MHz Line” 92 cm wavelength
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Haystack Observatory, Westford, MAArray: 24 stations
Station: 24 crossed Yagis Station Area: 12 m2
Station Beam: 14o
Beam Steering: +/- 40o
Frequency: 327.4 MHzBandwidth: 250 kHzChannels: 1024Resolution: 244 HzPolarization: Dual LinearSystem Temperature: 40 K + sky# Rx Ports: 48 x 24 = 1152
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D I Beam
Continuum
H I
Model D I Spectra
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Oct 2005
L = 183o
L = 171o
BlankFields
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GALACTIC ANTICENTER D/H ABUNDANCE L (deg) D/H x 10+5 Integration (yr)
183 2.3 +/- 0.4 6.5 RDCFKB
2.0 +/- 0.3 9.6 Oct 2005
171 1.5 +/- 0.5 7.2 RDCFKB
2.0 +/- 0.4 11.0 Oct 2005
195 1.7 +/- 0.8 3.1 RDCFKB
* Spin Temperture Range: 100-150 K
* Continuum Uniformly Distributed Along Line of Sight
* 1 Sigma measurement errors
=> <D/H> = (2.0+/-0.7) x 10-5 <=
for Rgal = (10+/-1) kpc
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I 3He
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3-Helium in Planetary Nebulae
Tom Bania (BU),
Bob Rood (UVa),
Dana Balser (NRAO),
Miller Goss (NRAO),
Cintia Quireza (ON, Brazil),
Tom Wilson (MPIfR)
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Observe 3He using the hyperfine (spin-flip) line of 3He+
Analog of the 21 cm line of H
= 8665.65 MHz = 3.36 cm
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NRAO 140 ft MPIfR 100 m
H II Regions Planetary Nebulae (PNe)
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3He+
H171interference
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200 Day Integration: 27 microKelvin RMS
He+3
H171 eta
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T = 50 Ksys
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“Simple” H II Regions
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Galli et al. (1995)
WMAP
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3He evolution with extra-mixing
protosolar
HII regions
3He/H x 105
Time (Gyr)
Tosi (1996)
70%
80%90%
100%
in agreement with Charbonnel & do Nascimento (1998): extra-mixing in 93-96 % of low-mass stars
is needed to explain the 12C/13C ratio in RGB stars
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Bania, Rood & Balser (2002)
3He Abundance in H II Regions -- The 3He Plateau
WMAP (3He/H)p = 1.1 x 10-5
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Bania, Rood, & Balser 2002
10 = 5.4+2.2-1.2
B = 0.04
Spergel et al. 2003, WMAP
10 = 6.5+0.4-0.3
B = 0.047 0.006
For D highest observed value is a lower limit for cosmological D
For 3He lowest observed 3He/H is an upper limit for cosmological 3He
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MPIfR 100 m PNe SurveyBalser, et al. 1997, ApJ 483, 320
106 hr
443 hr
Composite: NGC 6543 + NGC 6720 + NGC 7009 + NGC 7662 + IC 289
He+3
1987-1997
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NGC 3242 Confirmation Balser, et al.
1999 ApJ 522, L73
He+3
H171 eta
NRAO 140 ft spectrum is a 270 hour integration
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The rescue of the standard model
NGC 3242 (HST)
3He yes!
Rood, Bania & Wilson (1992)Balser, Rood & Bania (1999)
13C no!
Palla et al. (2002)
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3He abundance is a good test for cosmology, stellar evolution (standard and non-standard), and Galactic chemical evolution
Solving the 3-He Problem requires extra-mixing in ~ 90% of stars with
M ~ 2 M
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One is not enough!
Except in cosmology
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The PN sample:
PNe progenitor stars with no extra mixing:
4He / H < 0.125
[ N / O ] < -0.3
13C / 12C as low as possible
Oldest possible stellar population has highest 3-He:
Peimbert Class IIb, III, and IV
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The Robert C. Byrd
GREEN BANK TELESCOPE
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GBT: Surface Area is 8,000 m
2
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GBT: Mass is 7,300,000 kg
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GBT: Clear Aperture Optics
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S 209 H II Region 140 ft March 1995 GBT June 2004
33.1 hr 3.2 hr
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GBT S 209 H II Region
14.5 hour integration
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S 209 H II Region
14.5 hour integration 5 km/sec resolution
He+3H171 eta
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GBT PNe Composite SpectrumNGC 3242 + NGC 6543 + NGC 6826 + NGC
7009
H171 eta
He3 +
125.7 hour integration
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NGC7009 + NGC6543 + NGC6826
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This looks as real as He3 but is much too strong
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PNe He3 at the VLA: Balser, Goss, Bania, Rood (2005)
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VLA Planetary Nebula J320
3He / H abundance = 1.9 x 10 -3-3 by number\
Model
He3 +
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J320 3He+
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DataModel 35”
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Helium-3 Conclusions
• ~ 25% of PNe meet our selection criteria. To avoid conflict with Monica we should detect 3He in only 1/5.
• We detect 3He in the PN J320 with the VLA. The EVLA will be 10 x more sensitive than the VLA.
• We probably have found 3He in NGC 7009 with the GBT and may have another detection in NGC 6543.
• Proposal pressure on the GBT may not allow us to solidify these results in the near future.
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NAIC Arecibo Observatory 305 m
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Helium-3 Conclusions
• The scheduling mode and proposal pressure on the GBT may not allow us to solidify these results in the near future.
• We have found helium-3 in another PN, J320, using the VLA
• We probably have found helium-3 in NGC7009 using the GBT and may have a second detection in NGC6543
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3-Helium Experiment Status GBT now fully operational for 3-He
Two GBT 3-He epochs complete Spectral baselines of excellent quality Composite PNe spectrum consistent with
MPIfR survey results VLA 3-He 4-sigma detection' for PN J320
(see Balser et al. poster) First epoch NAIC Arecibo Observatory
observations complete
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Mixing and the 3He problem
Daniele Galli (INAF-Arcetri)Francesco Palla (INAF-Arcetri)Monica Tosi (INAF-Bologna)Federico Ferrini (Univ. Pisa)Letizia Stanghellini (HST)Oscar Straniero (INAF-Teramo)
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A long standing problemRood, Steigman & Tinsley (1976)
Low-mass stars produce substantial amounts of 3He, enriching the ISM: X310-3
But the measured protosolar value is much lower:
X310-5 problem!
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3He profile in a 1.25 M PopII star
Weiss, Wagenhuber & Denissenkov (1996)
ejected as a PN
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The “standard” 3He yields
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Theorists at work…
Wrong extrapolation of the 3He-3He nuclear cross section at low energies?
Pollution of winds from massive stars in HII regions?
Continuous infall of primordial gas?
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Mixing takes over
Charbonnel 1995 (see also Hogan 1995) : an extra-mixing mechanism acting during the RGB and/or AGB phases of stars with mass M 2 Mcan reduce the surface 3He abundance
Extra-mixing decreases the surface 12C/13C : the 3He problem is linked to other isotopic anomalies in RGB and AGB stars
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convective envelope
H-burning shell
He core
Mixing on the RGB
surface 3He destroyed
13C dredged-up
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Conclude reliability level for NGC7009 ~ 0.5 mK
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NGC7009
NGC6826
NGC6543
Sum
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He3 in S209 in only 7.5hr!
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A bonus: He++ or O++ RRL (a first?)
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Calibrating the mixing on the RGB
Charbonnel (1995)
0.8 M
Z=10-4
extra-mixing
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The “new” 3He yields
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NGC 3242
3He data from Balser et al. (1997, 1999)
stellar masses from Galli et al. (1997)
one more detection in a PN! (see poster by Balser et al.)
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Palla, Galli, Marconi, Stanghellini & Tosi (2002)
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Palla et al. (2000)
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Standard yields With mixing
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Bania, Rood & Balser (2002)
3He abundance in HII regions
(3He/H)p 1.1 10-5
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Bania, Rood, & Balser 2002
10 = 5.4+2.2
-1.2
B = 0.04
Spergel et al. 2003, WMAP
10 = 6.5+0.4
-0.3
B = 0.047 0.006
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GBT Conclusions
• There is still baseline structure (BS) probably resulting from the broadband feed, the polarizer, and or mismatches in the IF system.
BS varies with frequency sometimes almost invisible other times very problematic
BS amplitude is proportional to source continuum and moves with sky frequency
• Standing waves are not a problem
• At the mK level there are pseudo-lines
• In some AC bands there are short duration spikes in the ACF at seemingly random times, lags, and amplitudes