The infrared counterpart of GX 13+1

M. R. Garcia, J. E. Grindlay, C. D. Bailyn, J. L. Pipher, M. A. Shure, C. E. Woodward

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


We have discovered a bright (K = 12) infrared source which is likely the counterpart to the bright galactic bulge x-ray source GX 13+1. Observations with the MMT infrared photometer and the Rochester infrared Array camera at the IRTF allow determination of the source position to ∼0.7 arcsec, allow the infrared colors to be measured, and shows no variability on a 1 yr timescale. We consider four possible sources for the infrared emission, and conclude that it is most likely due to a K giant secondary. Future observations should allow more definite discrimination between the various possibilities. The discovery of a late-type giant secondary in GX 13+1 is contrary to the expectation that low-mass x-ray binaries (LMXB) which show quasiperiodic oscillations (QPO) have giant companions, while those which do not show QPO (like GX 13+1) have dwarf secondaries. The relation between the size of the scattered x-ray halo and the Av inferred from the infrared observations is compared to that found in other x-ray sources.

Original languageEnglish (US)
Pages (from-to)1325-1329
Number of pages5
JournalAstronomical Journal
Issue number4
StatePublished - Apr 1992


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