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J/ApJ/838/45  eta Carinae obs. around the 2014 X-ray minimum  (Corcoran+, 2017)

The 2014 X-ray minimum of η Carinae as seen by Swift. Corcoran M.F., Liburd J., Morris D., Russell C.M.P., Hamaguchi K., Gull T.R., Madura T.I., Teodoro M., Moffat A.F.J., Richardson N.D., Hillier D.J., Damineli A., Groh J.H. <Astrophys. J., 838, 45-45 (2017)> =2017ApJ...838...45C (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, X-ray Keywords: binaries: general; stars: individual: "eta Carinae", HD 93308; stars: winds, outflows; stars: early-type; stars: massive; X-rays: stars Abstract: We report on Swift X-ray Telescope observations of Eta Carinae (ηCar), an extremely massive, long-period, highly eccentric binary obtained during the 2014.6 X-ray minimum/periastron passage. These observations show that η Car may have been particularly bright in X-rays going into the X-ray minimum state, while the duration of the 2014 X-ray minimum was intermediate between the extended minima seen in 1998.0 and 2003.5 by Rossi X-Ray Timing Explorer (RXTE), and the shorter minimum in 2009.0. The hardness ratios derived from the Swift observations showed a relatively smooth increase to a peak value occurring 40.5 days after the start of the X-ray minimum, though these observations cannot reliably measure the X-ray hardness during the deepest part of the X-ray minimum when contamination by the "central constant emission" component is significant. By comparing the timings of the RXTE and Swift observations near the X-ray minima, we derive an updated X-ray period of PX=2023.7±0.7days, in good agreement with periods derived from observations at other wavelengths, and we compare the X-ray changes with variations in the HeII4686 emission. The middle of the "Deep Minimum" interval, as defined by the Swift column density variations, is in good agreement with the time of periastron passage derived from the HeIIλ4686 line variations. Description: The most recent X-ray observations of η Car by Swift began in 2014 April. Observations were scheduled twice per week at the outset. The Swift log of the 2014 observations discussed here is given in Table 1. For our discussion, we also include recalibrated fluxes from Rossi X-Ray Timing Explorer (RXTE), including previously unpublished observations from 2010 through 2011. See section 2. To study both orbit-dependent and non-orbit-dependent (secular) variations, we include in Table 2 data obtained by the RXTE-PCA in the interval 1996 February 9 through 2011 December 28. We re-reduced the entire RXTE data set in a consistent way. See section 4.1. Objects: ----------------------------------------------------- RA (ICRS) DE Designation(s) ----------------------------------------------------- 10 45 03.55 -59 41 04.0 eta Carinae = * eta Car ----------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 88 91 Swift X-ray telescope observations table2.dat 76 1345 Log of RXTE observations and corrected fluxes
See also: J/AJ/129/2018 : RXTE scaled fluxes of eta Car (Corcoran+, 2005) J/ApJS/175/191 : Variables from 2MASS calibration fields (Plavchan+, 2008) J/A+A/493/1093 : BVRI light curves of η Car (Fernandez-Lajus+, 2009) J/ApJS/194/15 : CCCP: Carina's diffuse X-ray emission (Townsley+, 2011) J/ApJ/751/73 : Equivalent widths in η Cat in 1998-2012 (Mehner+, 2012) J/A+A/578/A122 : eta Carinae's 2014.6 spectroscopic event (Mehner+, 2015) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 8 I8 --- ObsID Swift Observation ID 10- 19 A10 "Y/M/D" Date UT date of the Swift observation 21- 30 F10.4 d MJD [56752.7/57018.1] Modified Julian Date, JD-2400000.5 32- 36 F5.3 d Delta [0.01/1.7] Observation length in fraction of a day (Δ) 38- 42 F5.3 --- Phi [2.9/3.1] Phase (φ) (G1) 44- 49 F6.1 s Exp [348/5671]? Exposure time 51- 54 F4.2 10-13W/m2 Flux [0.03/3.8] Swift-XRT 2-10keV Flux, in 10-10erg/s/cm2 56- 59 F4.2 10-13W/m2 e_Flux [0.01/1] Uncertainty in Flux 61- 65 F5.2 --- HR [-0.8/0.4] Hardness Ratio (1) 67- 70 F4.2 --- e_HR [0.02/0.2] Uncertainty in HR 72- 76 F5.2 10+22cm-2 NH [2.3/46.5] Column density (NH) 78- 82 F5.2 10+22cm-2 E_NH [0.1/83] Upper uncertainty in NH 84- 88 F5.2 10+22cm-2 e_NH [0.1/37] Lower uncertainty in NH
Note (1): Hardness ratios calculated according to Eq. 1: HR=(C7-C3)/(C7+C3) where C7 and C3 are the gross counts in the 7±0.5 and 3±0.5keV bands, respectively.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Obs Observing Sequence, YYYYMMDDHH UT 17- 25 F9.3 d MJD [50122.6/55923.8] Modified Julian Date, JD-2400000.5 27- 31 F5.3 d Delta [0.001/0.04] Observation length in fraction of a day (Δ) 33- 38 F6.3 --- Phi [-0.4/2.6] Phase (φ) (G1) 40- 43 I4 s Exp [16/2672]? Exposure time 45- 48 F4.2 10-13W/m2 Flux [0.2/3.7] RXTE 2-10keV flux, in 10-10erg/s/cm2 50- 53 F4.2 10-13W/m2 e_Flux [0.01/0.3] Uncertainty in Flux 55- 59 F5.2 10-13W/m2 Fluxc [-0.08/3.6] Corrected Flux, in 10-10erg/s/cm2 (1) 61- 65 F5.2 ct/s Rate [2/37] Net count rate 67- 70 F4.2 ct/s e_Rate [0.1/2] Uncertainty in Rate 72- 76 F5.2 ct/s Bkg [10/21] Background count rate
Note (1): Flux corrected according to Eq. 2: Corr. RXTE Flux = (derived RXTE flux-0.314)/0.939
Global notes: Note (G1): φ is the time measured from the start of the X-ray minimum divided by the period of the orbit. φ=0 corresponds well to the start of the "Deep X-ray Minimum".
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 26-Oct-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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