Seimei KOOLS-IFU Mapping of
the Gas and Dust Distributions
in Galactic Planetary Nebulae:
Unveiling the origin and evolutionof Galactic halo PN H4-1
(accepted by PASJ, arXiv:2309.15099)
Masaaki Otsuka (Okayama Obs.)
Toshiya Ueta (U. of Denver)
Akito Tajitsu (NAOJ)

Question:
What Is the Origin and Evolution ofthe Enigmatic Halo Planetary Nebula H4-1?
H4-1 is believed to originate from a Pop II star and exhibit
very low metallicity (1/100 太陽金属量) and C-rich
However, assuming its initial mass is 0.8 Msun as a typical halo star,
1. H4-1 should be unable to become C-rich.
Because the third dredge-up required for being C-rich istheoretically taken place in an initially ~0.9 Msun or massive.
Q1: How did H4-1 become C-rich?
2. Over 15000 years is required for an initially ~0.9 Msun star
being enough hot (Teff > 30000K) to start photoionisation.
So, we should be unable to identify H4-1. Because nebula isalready very diffuse (<~ 10 H/cm3) when starting ionization.
Q2: How did H4-1 shorten evolutionary timescale?

We want to resolve the longstanding issues using KOOLS-IFU

Shh! The H2 Image is Telling Us
The Secret Story of H4-1…
• Abundant molecular H2Tajitsu, Otsuka, Ueta in prep.

• Equatorial attening disk withMultipolar nebulae

These are commonly seen in PNe
evolved from massive stars.
NO signatures of Binary star.
Has H4-1 experienced binary masstransfer/merger, then evolved intoa massive Single star?

disk

flIs H4-1 a descendant of a Binary Star?

Binary versus Single;
Through Gas Mass Accounting
To obtain con dent evidence of Binary origin
FACT: The mass of the PN central star is a typically ~0.5-0.6 Msun.
Then, if the progenitor is• Binary star (~0.8 Msun secondary and massive primary),
the ejected gas mass would be > 0.3 Msun.
Alternatively,• Single star (~0.8 Msun), the ejected gas mass would be< 0.3 Msun.

fiVerifying both binary and single star hypothesis
Through gas mass accounting using KOOLS-IFU

KOOLS-IFU - WHY We Select?
Because KOOLS-IFU can ACCURATELY measure
the ENTIRE ux from H4-1
Spectrum Quality：SNR > 3 per spaxel
Image Quality (moffat FWHM, arcsec)−0.20±0.01±(1.95 0.01) (λ/0.55)

for PSF-deconvolution every λPhotometry Quality using Pseudo
SDSS r-image• KOOLS-IFU： (1.75 ± 0.07) x 10-15• SDSS DR18：1.76 x 10-15
flin erg/cm2/s/Å 0.5% accuracy

KOOLS-IFU determines
Elem. Abundances and Gas Mass
Elemental abundances
The observed abundances can bereasonably explained by the 1.25
or 1.50 Msun models, EXCEPT forN, O, and Ne.

Initial mass CNONeSAr

1.25 Msun 8.94 6.66 7.31 6.95 5.00 4.27
1.50 Msun 9.26 6.80 7.56 7.68 5.00 4.29
H4-1

8.86 7.74 8.17 6.42 5.14 4.61

Gas mass, not including neutral hydrogen and molecules
24πD Ig μg−32±= (1.28 0.24) × 10 M⊙ Dkpc
mg =∑ ne jg(Te, ne)But, No Reliable Distance…
Distance need be constrained for Gas Mass Estimate. HOW?

KOOLS-IFU determines
the Range of Distance
In optically thick, nebula luminosity
is equal to central star luminosity, i.e.,
2Lneb = 4πD Ftot
Lcen = model prediction

(1)
(2)

Ftot

Eqs (1,2) give D for each initial mass andeach modeled Lcen as func of Teff and log g.

The derived D is veri ed using mg

2mg = (1.28 ± 0.24) × 10−3 M⊙ Dkpc
Initial mass

DPost-AGB age

0.85 Msun 11.9 - 20.8 kpc 57000 - 66000 yrs
8.6 - 10.5 kpc

4900 - 5400 yrs

1.50 Msun

7.7 - 9.6 kpc

4600 - 6600 yrs

fi

1.25 Msun

Lcen for 1.50Msun
Lcen for 1.25Msun

KOOLS-IFU gives Evidence ofBinary Star Origin Through TOTAL Gas MassGas Mass INCLUDING Neutral atomic gas and Molecules0.38 Msun, each 0.19 Msun ionized and neutral mass
For both initial 1.25 Msun and 1.50 Msun stars, which will end as
0.58 and 0.60 Msun WD.
Given our past experience in modeling PNe, the estimated neutral
gas mass is probably about 30-50% of the actual existing neutral gas
mass.
So, the sum of the central star and the TOTAL gas mass is
1.25 Msun: 0.58 Msun WD + (0.57-0.81) Msun gas = 1.15-1.39 Msun
1.50 Msun: 0.60 Msun WD + (0.59-0.86) Msun gas = 1.19-1.46 MsunH4-1 has evolved from a Pop II Binary Star.

Two Star Evolution models;
The Binary Origin and Evolution of H4-1
Over 300000 grid models using binary evolution/nucleosynthesis code predict• The progenitors of 1.87 Msun primary and 0.82 Msun secondary stars,
Formed about 4 Gyrs after the Big Bang.
• They underwent episodes of mass-transfers and an eventual binary merger;
the 0.60 Msun WD primary and the 0.82 Msun MS secondary star merged
into a 1.42 Msun star.
• Subsequently, this 1.42 Msun star evolved into H4-1 with the 0.62 Msun
WD central star.
• The observed N-excess would be due to a result of mass-transfer.
• The low Ne would be due to the high mass loss during the early AGB phase
He
Binary modelCNO

NeSAr

11.04 9.04 7.47 7.87 6.54 5.35 4.59

Initial abundance 10.90 6.06 4.64 6.82 6.06 5.26 4.49
H4-1

11.02 8.86 7.74 8.17 6.42 5.14 4.61