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

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ID# 25

4U 1728-34

GX 354-0, MX 1728-34

Candidate UCXB

RA                 Dec     [hh:mm:ss.ss]          [dd:mm:ss.ss] 17:31:57.68  -33:50:01.54                      [ICRS]

ℓ                      b [deg]                            [deg] 354.303524  -00.150417

Year of discovery: 1972

(Giacconi1972)

Basic data

Location in Globular Cluster
Type of accretor	NS	Persistent
Distance [kpc] (other distances)	3.3±0.5(H), 4.4±0.7 (He)	Galloway2020 Chelovekov2017
z [kpc]	-0.01	Galloway2020
Orbital period (Porb) [min]
Porb determination method
Thermonuclear X-ray burst	Short-B (He)	Hoffman1976Galloway2010
Peak X-ray flux [erg s-1 cm-2] (2 - 10 keV)	2.08E-09	Wang2019
NH [x1022 cm-2]	4.5±0.1	Wang2019
E(B-V) [mag]
Magnitude	K=15.1	Marti1998
Proposed companion	He WD (Type I X-ray bursts)	Galloway2010

NOTES

Galloway2010 reported the detection of a peak at 10.77 min in the power-density spectrum of the persistent X-ray emission with a significance between 3 and 4σ, suggesting it might be due to orbital modulation. However, analysis of other X-ray observations did not confirm the detection. Moreover, Vincentelli2020 found that the orbital period should be greater than 66 min, after the detection of an IR burst lagging an X-ray type I burst and interpreting it as reprocessing from the companion star. Burst oscillations were first observed in 1996, as a coherent signal at about 363 Hz (Strohmayer1996. See also Mahmoodifar2019). The source is detected with ALMA (300 GHz; DiazTrigo2017).

Spectral data

UV
Optical
X-ray	Fe Kα (6.7 keV), Mg XI emission line (1.66 keV) Emission (~0.5 keV) and absorption-like (~0.7 keV) features	diSalvo2000 Koliopanos2021

Peak Optical/NIR magnitudes

If the system is transient, quiescent magnitudes are indicated with a "q" superindex Marti1998 DiazTrigo2017
R >23.3, I>22.6, K=15.1, m_J=17.49±0.03, m_Ks=14.48±0.02

Aladin finding chart

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4U 1728-34 in Simbad

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References to finding charts

Marti1998