A cometary nucleus model taking into account all phase changes of water ice: amorphous, crystalline, and clathrate

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Volume 542 (June 2012)

A&A, 542 (2012) A82

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Table 1

Thermodynamic parameters of the materials.

Symbol	Name	Unity	Value

ρ ^b,l	Bulk density of solid l	kg m^-3
ρ ^b,d	Dust		3000
	Ices x
	H₂O		920
	CO		950^a
	CO₂		1562^b
	CH₄		507^c
	H₂S		1100^d

c ^l	Heat capacities of solids	J kg^-1 K^-1
c ^d	Dust		770^e
	Ices x
	H₂O
	crystalline		7.49 T + 90^f
	amorphous		7.49 T + 201^g
	CO
	Valid temperature range for values
	T ≤ 61.55 K		36.8 T − 242.52^h
	61.55 K ≤ T ≤ 68.1 K		1817.49^h
	CO₂		484 log(T) − 1325.03ⁱ
	H₂S
	Valid temperature range for values
	T ≤ 126.22 K		8.91 × 10^-2T² − 5514.46/T + 406.45^d
	T ≥ 126.22 K		85.12 T − 1.623 × 10⁶/T − 2.335 × 10⁴log (T) + 1.167 × 10⁵^d

k	Heat conductivities k of solids	J s^-1 m^-1 K^-1
k ^d	Dust		4.2^j
	Mantle of dust in surface		0.01^k
	Ices x
	H₂O
	amorphous		7.1 × 10^-3T^l
	crystalline		567/T^l
	CO		−1.43 × 10^-2T + 8.3 × 10^-1^m
	CO₂		167 600 T^-3.48+ 91/Tⁿ
	CH₄		−8.73 × 10^-3T log(T) + 4.25 × 10^-2T^o

H ^cr	Crystallization latent heat of water ice	J mol^-1	1620^p

	Equilibrium pressure of sublimation of ices	Pa
	CO
	Valid temperature range for values
	T ≤ 61.55 K		e^{10.43 − 721.3T^-1 − 1.07410⁴T^-2 + 2.34110⁵T^-3 − 2.39210⁶T^-4 + 9.47810⁶T^-5} × 10⁵^q
	61.55 K ≤ T ≤ 68.1 K		e^{10.25 − 748.2T^-1 − 5.84310³T^-2 + 3.93910⁴T^-3} × 10⁵^q
	CO₂
	Valid temperature range for values
	T ≤ 194.7 K		e^{14.76 − 2571T^-1 − 7.78110⁴T^-2 + 4.32510⁶T^-3 − 1.20710⁸T^-4 + 1.3510⁹T^-5} × 10⁵^q
	194.7 K ≤ T ≤ 216.58 K		e^{18.61 − 4154T^-1 + 1.04110⁵T^-2} × 10⁵^q
	CH₄		e^{10.51 − 1110T^-1 − 4341T^-2 + 1.03510⁵T^-3 − 7.9110⁵T^-4} × 10⁵^q
	H₂S
	Valid temperature range for values
	T ≤ 126.2 K		e^{12.98 − 2707T^-1} × 10⁵^q
	126.2 K ≤ T ≤ 187.57 K		e^{8.933 − 726T^-1 − 3.50410⁵T^-2 + 2.72410⁷T^-3 − 8.58210⁸T^-4} × 10⁵^q

References.

^(a)

Shinoda (1969);

^(b)

Air liquide;

^(c)

Stewart (1960);

^(d)

Giauque & Blue (1936);

^(e)

Prialnik et al. (2004);

^(f)

Giauque Stout (1936);

^(g)

Handa & Klug (1988);

^(h)

Clayton Giauque (1932);

⁽ⁱ⁾

Giauque Egan (1937);

^(j)

Ellsworth schubert (1983);

^(k)

Grun et al. (1993) and Huebner et al. (2006);

^(l)

Klinger (1980);

^(m)

data fit of Stachowiak et al. (1998);

⁽ⁿ⁾

data fit of Koloskova et al. (1974);

^(o)

data fit of Manzhelii & Krupskii (1968);

^(p)

Ghormley (1968);

^(q)

expressions given in Fray & Schmitt (2009).

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