J/A+A/710/A383 HD 75149 multi-epoch spectra (Chamoun-Contreras+, 2026)
Multi-epoch spectroscopic variability of the B supergiant HD 75149.
Chamoun-Contreras J., Arcos C., Machuca N., Perez-Ramirez C.E., Cidale L.S.,
Cure M., Araya I., Turis-Gallo D., Hadjara M.
<Astron. Astrophys. 710, A383 (2026)>
=2026A&A...710A.383C 2026A&A...710A.383C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, supergiant ; Radial velocities ; Equivalent widths ;
Spectra, optical
Keywords: stars: massive - stars: oscillations - stars: individual: HD 75149
Abstract:
Massive stars continuously enrich the surrounding interstellar medium
by supplying it with stellar material driven by their powerful winds.
B supergiant stars (BSGs) in particular are a type of massive star
characterized by strong winds and notable photometric and
spectroscopic variability.
We aim to conduct a pilot study of the optical spectroscopic
variability of the BSG HD 75149 between 2004 and 2025. Its extended
temporal baseline and pronounced variability amplitude make it
particularly well suited for investigating the physical origin of the
observed short-term variability within a consistent hydrodynamical and
radiative-transfer framework.
We analyzed 25 nightly averaged optical spectra obtained with
different instruments and telescopes, some of them with observations
over several consecutive days. We measured the radial velocities (RVs)
and equivalent widths (EWs) of 17 spectral lines (H, HeI, SiIII, NII,
MgII, CII). We modeled the Hα emission, absorption, and P-Cygni
profiles using the ISOSCELES grid and the delta-slow hydrodynamic
regime.
Hα shows variability in intervals of a few days, including
P-Cygni changes, while metal lines show small RV amplitudes,
consistent with pulsating oscillations. The largest variation in the
mass-loss rate corresponds to an increase of a factor of 1.8 within
four days. In contrast, the terminal velocity remains barely affected
during the same time interval.
The pronounced variation observed in hydrogen lines, in contrast with
the variability of other lines, suggests that it is due to mass-loss
rate episodes driven by a slow wind occurring on a timescale
comparable to photometric variations. We found no evidence of a close
binary companion in the sample used, but we cannot completely exclude
the possibility of a wide or low-inclination companion.
Description:
This data contains the tabular material from Appendix A of the paper.
It provides radial velocity (RV) and equivalent width (EW)
measurements for HD 75149 from 25 nightly-averaged optical spectra
obtained between 2004 and 2025. The analysed transitions include H,
HeI, SiIII, NII, MgII, and CII lines.
tablea1.dat gives the Halpha measurements. For spectra showing a
P-Cygni profile, the absorption and emission components are listed
separately in the same record. When the profile is purely absorption
or purely emission, the unused component is left blank.
tablea2.dat gives the day-to-day RV variation for each spectral line
in six observing windows: Feb 2013, Mar 2014, Apr 2014, Feb 2015,
Mar 2015, and Jan 2025. Subcolumns (1), (2), and (3) follow the
internal breakdown, which indicates consecutive days.
tablea3.dat gives the day-to-day EW variation for the same lines and
time windows as in tablea2.dat.
For tablea2.dat and tablea3.dat, missing values indicate that no
measurement is available.
Objects:
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RA (2000) DE Designation(s)
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08 46 30.54 -45 54 45.0 HD 75149 = V* OP Vel
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 65 28 *Halpha radial velocities and equivalent widths
tablea2.dat 90 16 *Day-to-day radial velocity variation by spectral
line and time interval
tablea3.dat 81 16 *Day-to-day equivalent width variation by spectral
line and time interval
list.dat 188 122 List of fits spectra
spferos/* . 6 FEROS spectra
spnres/* . 96 NRES-LCO spectra
spreosc/* . 20 REOSC-CASLEO spectra
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Note on tablea1.dat: The table contains one record per spectrum.
For P-Cygni profiles, both absorption and emission values are provided.
For purely absorption or emission profiles, the unused set of columns is blank.
Note on tablea2.dat, tablea3.dat: Subcolumns 1, 2, and 3 follow the internal
breakdown, which indicates consecutive days.
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.2 d JD Julian date of observation
11- 17 F7.2 km/s RVabs ? Radial velocity of the absorption component
19- 22 F4.2 km/s e_RVabs ? Radial velocity of the absorption component
uncertainty
27- 31 F5.3 0.1nm EWabs ? Equivalent width of the absorption component
33- 37 F5.3 0.1nm e_EWabs ? Equivalent width of the absorption component
uncertainty
39- 44 F6.2 km/s RVem ? Radial velocity of the emission component
46- 49 F4.2 km/s e_RVem ? Radial velocity of the emission component
uncertainty
54- 59 F6.3 0.1nm EWem ? Equivalent width of the emission component
61- 65 F5.3 0.1nm e_EWem ? Equivalent width of the emission component
uncertainty
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Line Spectral line identifier
12- 17 F6.3 km/s DRVFeb13-1 RV variation in Feb 2013,
internal subcolumn 1
19- 23 F5.3 km/s DRVFeb13-2 RV variation in Feb 2013,
internal subcolumn 2
25- 30 F6.3 km/s DRVMar14-1 RV variation in Mar 2014,
internal subcolumn 1
32- 36 F5.3 km/s DRVApr14-1 RV variation in Apr 2014,
internal subcolumn 1
38- 42 F5.3 km/s DRVApr14-2 RV variation in Apr 2014,
internal subcolumn 2
44- 49 F6.3 km/s DRVApr14-3 RV variation in Apr 2014,
internal subcolumn 3
51- 56 F6.3 km/s DRVFeb15-1 RV variation in Feb 2015,
internal subcolumn 1
58- 62 F5.3 km/s DRVFeb15-2 RV variation in Feb 2015,
internal subcolumn 2
64- 69 F6.3 km/s DRVMar15-1 RV variation in Mar 2015,
internal subcolumn 1
71- 76 F6.3 km/s DRVMar15-2 RV variation in Mar 2015,
internal subcolumn 2
78- 83 F6.3 km/s DRVMar15-3 RV variation in Mar 2015,
internal subcolumn 3
85- 90 F6.3 km/s DRVJan25-1 ? RV variation in Jan 2025,
internal subcolumn 1 (1)
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Note (1): Missing values indicate that no measurement is available.
---------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Line Spectral line identifier
11- 15 F5.3 0.1nm DEWFeb13_1 EW variation in Feb 2013,
internal subcolumn 1
17- 21 F5.3 0.1nm DEWFeb13_2 EW variation in Feb 2013,
internal subcolumn 2
23- 27 F5.3 0.1nm DEWMar14_1 EW variation in Mar 2014,
internal subcolumn 1
29- 33 F5.3 0.1nm DEWApr14_1 EW variation in Apr 2014,
internal subcolumn 1
35- 39 F5.3 0.1nm DEWApr14_2 EW variation in Apr 2014,
internal subcolumn 2
41- 45 F5.3 0.1nm DEWApr14_3 EW variation in Apr 2014,
internal subcolumn 3
47- 51 F5.3 0.1nm DEWFeb15_1 EW variation in Feb 2015,
internal subcolumn 1
53- 57 F5.3 0.1nm DEWFeb15_2 EW variation in Feb 2015,
internal subcolumn 2
59- 63 F5.3 0.1nm DEWMar15_1 EW variation in Mar 2015,
internal subcolumn 1
65- 69 F5.3 0.1nm DEWMar15_2 EW variation in Mar 2015,
internal subcolumn 2
71- 75 F5.3 0.1nm DEWMar15_3 EW variation in Mar 2015,
internal subcolumn 3
77- 81 F5.3 0.1nm DEWJan25_1 ? EW variation in Jan 2025,
internal subcolumn 1 (1)
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Note (1): Missing measurements are indicated by non-data.
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- Nx Number of pixels along X-axis
8- 12 I5 --- Ny Number of pixels along Y-axis
14- 23 A10 "datime" Obs.date Observation date
25- 31 F7.2 0.1nm blambda ? Lower value of wavelength interval
33- 39 F7.2 0.1nm Blambda ? Upper value of wavelength interval
41- 44 F4.2 0.1nm dlambda ? Wavelength resolution
46- 63 F18.10 d BJD ? BJD for NRES-LCO spectra
66- 82 F17.15 km/s RVcor ? Corrected RV for NRES-LCO spectra
85- 87 A3 --- Site ? Site, cpt or lsc, for NRES-LCO spectra
89- 92 I4 Kibyte size Size of FITS file
94-152 A59 --- FileName Name of FITS file, in subdirectory fits
154-188 A35 --- Title Title of the FITS file within subdirectory
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Acknowledgements:
Josephin Chamoun, josephin(at)live.cl
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 10-May-2026