J/A+A/706/A381 SN 2020nlb and SN 2020ue light curves (Izzo+, 2026)
Normal or transitional?
The evolution and properties of two type Ia supernovae in the Virgo cluster.
Izzo L., Gall C., Khetan N., Earl N., Hjorth J., Hoogendam W.B., Ni Y.Q.,
Sedgewick A., Ward S.M., Zenati Y., Auchettl K., Bhattacharjee S.,
Benetti S., Branchesi M., Cappellaro E., Catapano A., Chambers K.C.,
Coulter D.A., Davis K.W., Della Valle M., Dhawan S., de Boer T.,
Dimitriadis G., Foley R.J., Fulton M., Gao H., Hon W.J., Huber M.E.,
Jones D.O., Kilpatrick C.D., Lin C.C., Lowe T.B., Magnier E.A., Mandel K.S.,
Margutti R., Narayan G., Ochner P., Pan Y.C., Reguitti A., Rojas-Bravo C.,
Siebert M., Smartt S.J., Smith K.W., Srivastav S., Swift J.J., Taggart K.,
Terreran G., Thorp S., Tomasella L., Wainscoat R.J.
<Astron. Astrophys. 706, A381 (2026)>
=2026A&A...706A.381I 2026A&A...706A.381I (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Photometry, UBVRI ; Photometry, SDSS ; Ultraviolet
Keywords: supernovae: general - supernovae: individual: SN 2020ue -
supernovae: individual: SN 2020nlb - distance scale
Abstract:
Type Ia supernovae (SNe Ia) are among the most precise cosmological
distance indicators used to study the expansion history of the
Universe. The vast increase of SN Ia data due to large-scale
astrophysical surveys has led to the discovery of a wide variety of SN
Ia sub-classes, such as transitional and fast-declining SNe Ia.
However, their distinct photometric and spectroscopic properties
differentiate them from the population of normal SNe Ia such that
their use as cosmological tools remains challenged. Here, we present a
high-cadenced photometric and spectroscopic dataset of two SNe Ia, SNe
2020ue and 2020nlb, which were discovered in the nearby Virgo cluster
of galaxies. Our study shows that SN 2020nlb is a normal SN Ia whose
unusually red color is intrinsic, arising from a lower photospheric
temperature rather than interstellar reddening, providing clear
evidence that color diversity among normal SNe Ia can have a physical
origin. In contrast, SN 2020ue has photometric properties, such as
color evolution and light-curve decay rate, similar to those of
transitional SNe, spectroscopically it is more aligned with normal SNe
Ia. This is evident from spectroscopic indicators such as the
pseudo-equivalent width of Si ii lines. Thus, such SNe Ia that are
photometrically at the edge of the standard normal SNe Ia range may be
missed in cosmological SNe Ia samples. Our results highlight that
spectroscopic analysis of SNe Ia around peak brightness is crucial for
identifying intrinsic color variations and constructing a more
complete and physically homogeneous SN Ia
Description:
Sample for precision cosmology.
The following tables contain the photometric observations of SN 2020ue
and SN 2020nlb from various observational facilities.
Objects:
-----------------------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------------------
12 42 46.77 +02 39 34.1 SN2020ue = SN 2020ue
12 25 24.17 +18 12 12.7 SN2020nlb = ZTF20abijfqq
-----------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
sn.dat 34 2 List of studied SN
tables.dat 55 1695 Tables of the photometry
--------------------------------------------------------------------------------
Byte-by-byte Description of file: sn.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name SN name (SN 2020nlb or SN 2020ue)
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 22 F5.2 s RAs Right ascension (J2000)
24 A1 --- DE- Declination sign (J2000)
25- 26 I2 deg DEd Declination (J2000)
28- 29 I2 arcmin DEm Declination (J2000)
31- 34 F4.1 arcsec DEs Declination (J2000)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tables.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name SN name (SN 2020nlb or SN 2020ue)
12- 13 A2 --- Band Observed band
15- 22 F8.2 d MJD Modified Julian date
24- 29 F6.2 d Phase Phase
31- 35 F5.2 mag mag Magnitude in Band (1)
37- 40 F4.2 mag e_mag Magnitude in Band error
42- 55 A14 --- Tel Telescope
--------------------------------------------------------------------------------
Note (1): All magnitudes reported in the tables are as observed and have not
been corrected for Galactic or host galaxy extinction unless otherwise
specified in the manuscript.
--------------------------------------------------------------------------------
Acknowledgements:
Luca Izzo, luca.izzo(at)inaf.it
(End) Patricia Vannier [CDS] 27-Jan-2026