J/A+A/681/A10 Spectro-photometry of 1A 0535+262 (Liu+, 2024)
Multiwavelength observation of 1A 0535+262=HD 245770 from 2010 to 2021.
Liu W., Yan J., Xiao G., Li X., Gao B., Liu Q.
<Astron. Astrophys., 681, A10 (2024)>
=2024A&A...681A..10L 2024A&A...681A..10L (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, X-ray ; Photometry, UBVRI ; Equivalent widths
Keywords: stars: emission-line, Be - binaries: close - X-rays: binaries -
stars: individual: 1A 0535+262 - stars: neutron
Abstract:
1A 0535+262 is a high-mass X-ray binary that went into a giant X-ray
outburst in 2020. During this event, the X-ray luminosity reached the
highest value measured over the last 30 years.
Our aim is to study the long-term variability of 1A 0535+262 before
and after the 2020 major X-ray outburst and to uncover the mechanism
that led to the X-ray outburst.
We used the long-term photometric light curve and the equivalent
widths of the Hα and HeI λ6678 lines to monitor the
state of the Be star's circumstellar disk. The Hα line profiles
show evidence for V/R variability, which we revealed by fitting the
Hα spectral line profiles with two Gaussian functions. In
addition, we divided our data into four periods according to the
intensity of the X-ray, optical, and infrared emission.
The Hα line profiles show single-peaked profiles in most cases.
This is consistent with the previously reported orbital inclination of
i=37°±2°. Unlike the Hα lines, the HeI λ6678
lines show a maximal intensity in October 2020, which is one month
before the giant X-ray outburst in 2020. Based on the behavior of the
equivalent widths of the Hα and HeI λ6678 lines, and the
V-band magnitude, we find two mass ejection processes from the Be star
to the Be disk on MJD 55820 and MJD 56600. The V/R quasi-period is
about two years during 2011-2015, which is different from 1994 to
1995. Furthermore, the periods I -> II -> III -> IV in the (B-V) color
index versus V-band magnitude diagram constitute a cycle. From the
behavior of the V/R ratio of Hα lines, and the variability of
the V band, we believe that the precession of the density perturbation
inside the disk is retrograde.
Description:
Optical spectroscopic observations were obtained from two telescopes
at two different observatories: most observations from the Xinglong
Station of National Astronomical Observatories in Hebei province
(China) were made with the spectrometer OptoMechanics Research (OMR)
or BAO Faint Object Spectrograph and Camera (BFOSC) on the 2.16 m
telescope; other data from the Lijiang station of Yunnan Astronomical
Observatory in Yunnan province (China) came from the spectrometer
Yunnan Faint Object Spectrograph and Camera (YFOSC) on the 2.4 m
telescope.
Table A.1 gives the summaries of the spectroscopic observations. This
table contains instrumental information and the results of the
spectral analysis: the equivalent widths of the Hα lines and the
He I λ6678 lines.
Table A.2 gives V/R ratio and peak separation.
Optical photometric observations are obtained from three telescopes at
two different observatories: the data from the Xinglong Station of
National Astronomical Observatories were made with the 80 cm
Tsinghua-NAOC Telescope (TNT) and the 60 cm telescope; the data from
the Lijiang station of Yunnan Astronomical Observatory come from the
2.4 m telescope.
In all three telescopes, 1A 0535+262 was observed through the standard
Johnson-Cousins B, V, R, and I filters.
The photometric magnitudes are given in Table B.1.
Objects:
---------------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------------
05 38 54.57 +26 18 56.8 1A 0535+262 = HD 245770
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 64 96 Summary of spectroscopic observations of
1A 0535+262
tablea2.dat 54 94 V/R ratio and peak separation of 1A 0535+262
tableb1.dat 63 141 Summary of photometric observations of 1A 0535+26
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See also:
J/PAZh/26/13 : Observations of X-ray binary A0535+26/V725 Tau (Lyuty+, 2000)
J/PAZh/31/116 : X-ray binary A0535+26/V725 Tau UBV photometry (Zaitseva, 2005)
J/ApJ/660/1398 : Spectro. monitoring of HDE 245770 & X Per (Grundstrom+, 2007)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "date" Date Observation date
12- 21 F10.4 d MJD Modified Julian date
23- 27 A5 --- Tel Telescope
28 A1 --- --- [/]
29- 33 A5 --- Inst Instrument
35- 38 I4 0.1nm blambda Lower value of wavelength interval
39 A1 --- --- [-]
40- 43 I4 0.1nm Blambda Upper value of wavelength interval
45- 49 F5.1 0.1nm EWHa Hα equivalent width
51- 53 F3.1 0.1nm e_EWHa Hα equivalent width error
55- 59 F5.2 0.1nm EWHI HeI λ6678 equivalent width
61- 64 F4.2 0.1nm e_EWHI HeI λ6678 equivalent width error
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "date" Date Observation date
12- 21 F10.4 d MJD Modified Julian date
23- 27 A5 --- Tel Telescope
28 A1 --- --- [/]
29- 33 A5 --- Inst Instrument
35- 38 I4 0.1nm blambda Lower value of wavelength interval
39 A1 --- --- [-]
40- 43 I4 0.1nm Blambda Upper value of wavelength interval
45- 50 F6.3 --- logV/RHa V/R variability of Hα line (1)
52- 54 I3 km/s DV(Ha) Peak separation of the violet and red peaks
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Note (1): The V/R variability is defined as the ratio V/R=(I(V)-Ic)/(I(R)-Ic),
where I(V), I(R), and Ic are the intensities of the violet peak, red peak,
and continuum, respectively.
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Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 d MJD Modified Julian date
12- 15 A4 --- Tel Telescope
17- 21 F5.3 mag Bmag ?=- Johnson B magnitude
23- 27 F5.3 mag e_Bmag ? Johnson B magnitude error
29- 33 F5.3 mag Vmag ?=- Johnson V magnitude
35- 39 F5.3 mag e_Vmag ? Johnson V magnitude error
41- 45 F5.3 mag Rmag ?=- Cousins R magnitude
47- 51 F5.3 mag e_Rmag ? Cousins R magnitude error
53- 57 F5.3 mag Imag ?=- Cousins I magnitude
59- 63 F5.3 mag e_Imag ? Cousins I magnitude error
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 22-Apr-2024