J/A+A/686/A160 Gaia18cjb LT, LBT, NTT and GTC spectra (Fiorellino+, 2024)
The enigma of Gaia18cjb: a possible rare hybrid of FUor and EXor properties?
Fiorellino E., Abraham P., Kospal A., Kun M., Alcala J.M.,
Caratti o Garatti A., Cruz-Saenz de Miera F., Garcia-Alvarez D.,
Giannini T., Park S., Siwak M., Szilagyi M., Covino E., Marton G., Nagy Z.,
Nisini B., Szabo Z.M., Bora Z., Cseh B., Kalup C., Krezinger M.,
Kriskovics L., Ogloza W., Pal A., Sodor A., Sonbas E., Szakats R., Vida K.,
Vinko J., Wyrzykowski L., Zielinski P.
<Astron. Astrophys. 686, A160 (2024)>
=2024A&A...686A.160F 2024A&A...686A.160F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; YSOs ; Spectra, infrared
Keywords: accretion, accretion disks - techniques: imaging spectroscopy -
stars: formation - stars: low-mass - stars: pre-main sequence -
stars: protostars
Abstract:
Gaia18cjb is one of the Gaia-alerted eruptive young star candidates
which has been experiencing a slow and strong
brightening during the last 13 years, similar to some FU Orionis-type
objects.
The aim of this work is to derive the young stellar nature of
Gaia18cjb, determine its physical and accretion properties to classify
its variability.
We conducted monitoring observations using multi-filter optical and
near-infrared photometry, as well as near-infrared spectroscopy. We
present the analysis of pre-outburst and outburst optical and infrared
light curves, color-magnitude diagrams in different bands, the
detection of near-IR spectral lines, and estimates of both stellar and
accretion parameters during the burst.
The optical light curve shows an unusually long (8 years) brightening
event of 5mag in the last 13 years, before reaching a plateau
indicating that the burst is still on-going, suggesting a FUor-like
nature. The same outburst is less strong in the infrared light curves.
The near-infrared spectra, obtained during the outburst, exhibit
emission lines typical of highly accreting low-intermediate mass young
stars with typical EXor features. The spectral index of Gaia18cjb SED
classifies it as a Class I in the pre-burst stage and a Flat Spectrum
young stellar object (YSO) during the burst.
Gaia18cjb is an eruptive YSO which shows FUor-like photometric
features (in terms of brightening amplitude and length of the burst)
and EXor-like spectroscopic features and accretion rate, as V350 Cep
and V1647 Ori, classified as objects in between FUors and EXors.
Description:
On 2020 November 11 we observed Gaia18cjb in the visible
at low resolution (R=350) with the SPectrograph for the Rapid
Acquisition of Transients (SPRAT), mounted on the Liverpool Telescope
(LT).
We observed Gaia18cjb at the Large Binocular Telescope
(LBT Observatory, Arizona) with LUCI1 and LUCI2 instruments in the zJ
and HK filters on 2021 January 17.
The blue part (0.95-1.64um) of NTT/SOFI spectrum was observed on the
2021 May 5 and 8, while the red part (1.53-2.52um) only on the 8th.
We obtained JHK-band spectroscopy of Gaia18cjb with
the GTC/EMIR medium-resolution multi-object spectrograph
in long slit mode on 2022 October 26.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
06 39 07.54 +00 08 54.49 Gaia18cjb
-----------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
hksummed.dat 36 1893 HK reduced spectrum from LBT, SNR summed between
LBT a and b
zjsummed.dat 36 1874 zJ reduced spectrum from LBT, SNR summed between
LBT a and b
spect.dat 50 433 Reduced, not flux calibrated LT spectrum
list.dat 198 5 List of GTC and NTT-SOFI fits spectra
fits/* . 5 Individual fits spectra
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Byte-by-byte Description of file: hksummed.dat zjsummed.dat
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Bytes Format Units Label Explanations
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3- 20 F18.16 nm lambda Wavelength
27- 36 F10.4 ct Flux Flux not normalized
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Byte-by-byte Description of file: spect.dat
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Bytes Format Units Label Explanations
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1- 24 E24.19 0.1nm lambda Wavelength
25- 50 E26.19 10mW/m2/nm Flux Flux
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 24 F5.3 arcsec/pix Scale ? Scale of the image
26- 29 I4 --- Nx Number of pixels along X-axis
31- 34 I4 --- Ny ? Number of pixels along Y-axis
36- 59 A24 "datime" Obs.date Observation date
61- 68 F8.2 0.1nm bLAMBDA ? Lower value of wavelength interval
70- 76 F7.1 0.1nm BLAMBDA ? Upper value of wavelength interval
78- 85 F8.5 0.1nm dLAMBDA ? Wavelenght resolution
87- 91 I5 Kibyte size Size of FITS file
93-133 A41 --- FileName Name of FITS file, in subdirectory fits
135-198 A64 --- Title Title of the FITS file
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Acknowledgements:
Eleonora Fiorellino, eleonora.fiorellino(at)inaf.it
(End) Patricia Vannier [CDS] 14-Mar-2024