Cyclical accretion regime change in the slow X-ray pulsar 4U 0114+65 observed with Chandra

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Table 1.

Main astrophysical parameters of 4U 0114+65.

Companion
Spectral Type	B1Ia	Reig et al. (1996)
T_eff (K)	24 000 ± 3000	Reig et al. (1996)
Radius (R_⊙)	37 ± 15	Reig et al. (1996)
Mass (M_⊙)	16 ± 5	Reig et al. (1996)


System

d (kpc)	$4 . 5_{- 0.2}^{+ 0.3}$ $4.5 ^{+0.3}_{-0.2}$	Bailer-Jones et al. (2021)
M_V	−7 ± 1	Reig et al. (1996)
E(B − V)	1.24 ± 0.02	Reig et al. (1996)
BC	−2.3 ± 0.3	Reig et al. (1996)
M_bol	−9.3 ± 1.0	Reig et al. (1996)
L_X(× 10³⁶ erg s⁻¹)	0.1–1.3	This work

P_orb (days)	11.6 ± 0.1	Grundstrom et al. (2007)
P_superorb (days)	30.7 ± 0.1	Farrell et al. (2006)
P_pulse (s)	9050 ± 100	This work

Inclination	∼45°	Grundstrom et al. (2007) & This work
Eccentricity	0.18 ± 0.05	Grundstrom et al. (2007), Crampton et al. (1985)
Angle to the periapsis	11 ± 11°	Grundstrom et al. (2007)
v sin i	96 ± 20	Reig et al. (1996)
v_∞ (km/s)	1200	Reig et al. (1996)

R_BONDI(cm)	≈10¹¹
R_COROTATION(cm)	≈7 × 10¹⁰
R_ALFVEN(cm)	≈1.7 × 10¹⁰

Notes. The velocity of the stellar wind at the location of the NS was determined using the β-law equation: $v_{wind} = v_{\infty} {(1 - \frac{R_{*}}{a})}^{β}$ $v_{\mathrm{wind}}=v_\infty\left(1-\frac{R_*}{a}\right)^\beta$ where β = 0.8 (Lamers & Cassinelli 1999). R_* refers to the companion star radius, where R_BONDI is $R_{B} \approx \frac{2 G M}{v_{w}^{2} + v_{orb}^{2}}$ $R_B \approx \frac{2GM}{v_w^2 + v_{\text{ orb}}^2}$ , R_COROTATION $R_{cor} \approx {(\frac{G M P_{*}}{4 π^{2}})}^{1 / 3}$ $R_{\text{ cor}} \approx \left(\frac{GMP_*}{4\pi ^2}\right)^{1/3}$ , and R_ALFVEN corresponds to the magnetospheric boundary.

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