4U 0115+634

Other Names

• V635 Cassiopeiae (SIMBAD)

General Characteristics

• optical companion: O9e star ()
• distance: <latex> 7-8\,\text{kpc} </latex> ()

Orbital Parameters

• orbital period: [math]\displaystyle{ P_{\text{Orb}} = 24.31617^{+0.00005}_{-0.00007}\,\text{d} }[/math] (Müller et al. in prep.)
• epoch of periastron passage: [math]\displaystyle{ T_0 = 49279.2677(34)\,\text d }[/math] ()
• projected semimajor axis:[math]\displaystyle{ a_{\text x}\sin i = 140.13(8)\,\text{lt-s} }[/math] ()
• eccentricity:[math]\displaystyle{ e = 0.3402(2) }[/math] ()
• longitude of periastron: [math]\displaystyle{ \omega = 47.66(9)^{\circ} }[/math] ()

Pulsations

• pulse profiles strongly energy dependent (Müller et al. in prep.)
  • double peaked at low energies
  • single peaked at high energies
• phase lags at the energies of cyclotron scattering features (Ferrigno et al. submitted)

Quantitative Spectral Analysis

• outburst 1999 (,)
  • NPEX x CYAB (x CYAB) describes the RXTE-observation well
  • Becker & Wolff model and Soft Thermal Comptonization describes one Beppo-SAX observation well

• outburst 2008 (Müller et al. in prep.)
  • (PL x FDcut + BlackBody + 10keV feature) x GAUABS x GAUABS describes the RXTE-observation well (preliminary)

Cyclotron Features

• fundamental resonance at ~11 keV (, )
• second harmonic at ~23 keV (, , )
• third harmonic at ~36 keV ()
• fourth harmonic at ~50 keV ()
• fifth harmonic at ~60 keV (, )

References