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

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ID# 19

MAXI J1957+032

IGR J19566+0326

Confirmed UCXB

RA                 Dec     [hh:mm:ss.ss]          [dd:mm:ss.ss] 19:56:39.11  +03:26:43.66                      [ICRS]

ℓ                      b [deg]                            [deg] 043.645509  -12.825722

Year of discovery: 2015

(Negoro2015bCherepashchuk2015)

Basic data

Location in Globular Cluster
Type of accretor	NS AMXP (313.64 Hz / 3.18 ms)	Transient Sanna2022
Distance [kpc] (other distances)	5 ±2	MataSanchez2017aRavi2017
z [kpc]	-1.11	MataSanchez2017aRavi2017
Orbital period (Porb) [min]	60.8841±0.0010	Sanna2022
Porb determination method	X-ray pulsation
Thermonuclear X-ray burst
Peak X-ray flux [erg s-1 cm-2] (2 - 10 keV)	4.91E-10	MataSanchez2017a
NH [x1022 cm-2]	0.17	MataSanchez2017a
E(B-V) [mag]
Magnitude	R=18.27±0.06 qR=21.4±0.2	Guver2015 MataSanchez2017a
Proposed companion

NOTES

An optical counterpart (late-K/early-M dwarf star) has been identified during the X-ray quiescence phase, setting a constraint on the source distance (Ravi2017). However, the outburst properties lead the author to suggest that the observed counterpart is likely not the mass donor. Instead, it is suggested to be a possible triple system, with the main-sequence counterpart likely being in a wide orbit around a compact interacting binary.

Spectral data

UV
Optical	Featureless	MataSanchez2017a
X-ray	Featureless	MataSanchez2017aSanna2022

Peak Optical/NIR magnitudes

If the system is transient, quiescent magnitudes are indicated with a "q" superindex MataSanchez2017a MataSanchez2017a Guver2015 Baglio2022
qR=21.4±0.2, B=18.5±0.3, U=18.7±0.3, UVW1=18.5±0.3(Vega), UVM2=18.3±0.2(Vega), UVW2=18.1±0.2(Vega), r'=18.5±0.15, R=18.27±0.06, g'=18.98±0.05, i'=18.59±0.06

Aladin finding chart

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MAXI J1957+032 in Simbad

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Pan-STARRS1 finding chart

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References to finding charts

MataSanchez2017a