J/ApJ/898/77 NIR spectra of 2 extreme T-type subdwarfs (Schneider+, 2020)
WISEA J041451.67-585456.7 and WISEA J181006.18-101000.5: the first extreme
T-type subdwarfs?
Schneider A.C., Burgasser A.J., Gerasimov R., Marocco F., Gagne J.,
Goodman S., Beaulieu P., Pendrill W., Rothermich A., Sainio A.,
Kuchner M.J., Caselden D., Meisner A.M., Faherty J.K., Mamajek E.E.,
Hsu C.-C., Greco J.J., Cushing M.C., Kirkpatrick J.D.,
Bardalez-Gagliuffi D., Logsdon S.E., Allers K., Debes J.H.
<Astrophys. J., 898, 77 (2020)>
=2020ApJ...898...77S 2020ApJ...898...77S
ADC_Keywords: Spectra, infrared; Stars, T-type; Stars, brown dwarf
Keywords: T subdwarfs ; Brown dwarfs ; Subdwarf stars ; T dwarfs
Abstract:
We present the discoveries of WISEAJ041451.67-585456.7 and
WISEAJ181006.18-101000.5, two low-temperature (1200-1400K), high
proper motion T-type subdwarfs. Both objects were discovered via their
high proper motion (>0.5yr-1); WISEA J181006.18-101000.5 as part of
the NEOWISE proper motion survey and WISEA J041451.67-585456.7 as part
of the citizen science project Backyard Worlds; Planet 9. We have
confirmed both as brown dwarfs with follow-up near-infrared
spectroscopy. Their spectra and near-infrared colors are unique among
known brown dwarfs, with some colors consistent with L-type brown
dwarfs and other colors resembling those of the latest-type T dwarfs.
While no forward model consistently reproduces the features seen in
their near-infrared spectra, the closest matches suggest very low
metallicities ([Fe/H]≤-1), making these objects likely the first
examples of extreme subdwarfs of the T spectral class (esdT).
WISEAJ041451.67-585456.7 and WISEA J181006.18-101000.5 are found to be
part of a small population of objects that occupy the "substellar
transition zone", and have the lowest masses and effective
temperatures of all objects in this group.
Description:
We observed WISEA J041451.67-585456.7 with the Folded-port Infrared
Echellette (FIRE) spectrograph at the 6.5m Baade Magellan telescope on
2020 February 12. Observations were taken using the 0.6" slit in prism
mode which achieves a resolving power between 500 and 300 across the
J, H, and K bands (0.8-2.5um).
We observed WISEA J181006.18-101000.5 with the TripleSpec instrument
on the Palomar 200 inch telescope on 2019 September 19. The spectrum
covers a wavelength range of ∼1.0-2.4um at a resolution of R∼2600.
Objects:
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RA (ICRS) DE Designation(s)
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04 14 51.67 -58 54 56.7 WISEA J0414-5854 = WISEA J041451.67-585456.7
18 10 06.18 -10 10 00.5 WISEA J1810-1010 = WISEA J181006.18-101000.5
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
w0414.dat 39 1888 Near-infrared spectra of WISEA J041451.67-585456.7
w1810.dat 51 5957 Near-infrared spectra of WISEA J181006.18-101000.5
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See also:
II/328 : AllWISE Data Release (Cutri+ 2013)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
J/AJ/113/806 : M-Subdwarfs (Gizis 1997)
J/A+A/410/527 : Abundances in the Galactic disk (Bensby+, 2003)
J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007)
J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)
J/A+A/493/L27 : Parallaxes of 10 ultracool subdwarfs (Schilbach+, 2009)
J/ApJS/190/100 : NIR proper motion survey using 2MASS (Kirkpatrick+, 2010)
J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)
J/MNRAS/433/457 : 76 T dwarfs from the UKIDSS LAS (Burningham+, 2013)
J/MNRAS/430/1171 : Sub-stellar birth rate from UKIDSS (Day-Jones+, 2013)
J/ApJ/783/122 : AllWISE motion survey (Kirkpatrick+, 2014)
J/ApJ/787/126 : WISE reduced PMs and spectral types (Luhman+, 2014)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
J/ApJ/810/158 : M,L,T dwarfs fundamental param. and SEDs (Filippazzo+, 2015)
J/MNRAS/449/3651 : L and T dwarfs from UKIDSS LAS (Marocco+, 2015)
J/ApJS/224/36 : The AllWISE motion survey (AllWISE2) (Kirkpatrick+, 2016)
J/ApJ/817/112 : NEOWISE/AllWISE high PM objects (Schneider+, 2016)
J/AJ/155/34 : Analysis of neighboring L dwarfs NIR spectra (Cruz+, 2018)
J/AJ/158/182 : Discoveries from the NEOWISE PM survey (Greco+, 2019)
J/A+A/628/A61 : X-shooter spectra of 43 metal-poor M dwarfs (Lodieu+, 2019)
J/ApJS/240/31 : M-subdwarf research. I. LAMOST DR4 spectra (Zhang+, 2019)
J/ApJ/889/176 : Very low-mass binaries with Gaia DR2 data (Faherty+, 2020)
J/ApJ/889/74 : Spitzer follow-up of Y brown dwarfs (Meisner+, 2020)
Byte-by-byte Description of file: w0414.dat
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Bytes Format Units Label Explanations
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1- 10 F10.8 um lambda [0.77/2.53] Wavelength
12- 25 E14.7 cW/m2/nm Fluxl [-4.66e-14/1.96e-13] Flux (lambda*Flambda)
in erg/cm2/s/Å units
27- 39 E13.7 cW/m2/nm e_Fluxl [1.05e-22/2.43e-13] Uncertainty in Fluxl
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Byte-by-byte Description of file: w1810.dat
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Bytes Format Units Label Explanations
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1- 14 F14.12 um lambda [0.97/2.47] Wavelength
16- 33 E18.11 cW/m2/nm Fluxl [-5.55e-16/6.38e-16] Flux (lambda*Flambda)
in erg/cm2/s/Å units
35- 51 E17.11 cW/m2/nm e_Fluxl [2.97e-18/5.24e-16] Uncertainty in Fluxl
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Nov-2021