UltraCompCAT A Catalogue of Ultra-Compact and Short Orbital Period X-ray Binaries

« Previous object   Next object »

ID# 10

4U 1626-67

KZ TrA, 4U 1627-673

Confirmed UCXB

RA                 Dec     [hh:mm:ss.ss]          [dd:mm:ss.ss] 16:32:16.79  -67:27:39.3                      [ICRS]

ℓ                      b [deg]                            [deg] 321.788351  -13.091711

Year of discovery: 1972

(Giacconi1972)

Basic data

Location in Globular Cluster
Type of accretor	NS	Persistent
Distance [kpc] (other distances) Gaia [kpc]	~8 3.5+2.3-1.3 (not in 1")	Chakrabarty1998 Schulz2019 BailerJones2018
z [kpc]	-1.81	Chakrabarty1998
Orbital period (Porb) [min]	41.538±0.002	Middleditch1981
Porb determination method	Optical pulsation
Thermonuclear X-ray burst
Peak X-ray flux [erg s-1 cm-2] (2 - 10 keV)	2.96E-10	Hemphill2021
NH [x1022 cm-2]	0.13+0.04-0.03	Krauss2007
E(B-V) [mag]
Magnitude	V=18.54±0.11	McClintock1977
Proposed companion	CONe or ONeMg WD CO or ONeMg WD CO WD (FUV spectrum X-ray spec Opt spec)	Homer2002 Schulz2001 Werner2006 Nelemans2006

NOTES

The magnetic field strength of the pulsar is estimated to be ~(3-4)E12 G, based on the cyclotron resonance scattering feature at ~37 keV (Orlandini1998). The pulsar spun up until 1990 (Chakrabarty1997), when it began a period of spin-down and dimming. Then, it exhibited a torque reversal back to spin-up in 2008, accompanied by an increase in flux (Camero-Arranz2012).

Spectral data

UV	Lyα λ1215; CIII λ1176; O IV Triplet λ1342; O V λ1371; Si IV λλ1394, 1403 Doublet Plus O IV] λ1401 Blend; C IV Double λ1549; O III] Multiplet λλ1661-1669 (see Table 1 more lines).	Homer2002
Optical	CO emission lines	Werner2006 Nelemans2006
X-ray	Double-peaked emission lines: Ne X (12.13 Å), Ne IX triple (13.44 Å), O VIII (18.97 Å), O VII triplet (21.6 Å) Fe-L shell fluorescence emission line (0.73 keV) Variable Fe Kα (6.4 keV) Electron cyclotron absorption feature (~37 keV)	Angelini1995Schulz2001Krauss2007 Beri2018 Camero-Arranz2012Iwakiri2012Koliopanos2016 Orlandini1998

Peak Optical/NIR magnitudes

If the system is transient, quiescent magnitudes are indicated with a "q" superindex Chakrabarty1998 McClintock1977
R=18.68±0.26, V=18.54±0.11, B=18.67±0.11, U=17.47±0.15

Aladin finding chart

Scroll to zoom. Set survey image in "Manage layers"
Default image: DSS2 Red

4U 1626-67 in Simbad

---

References to finding charts

Bradt1977