Spectroscopic Follow-up of Discoveries from the NEOWISE Proper Motion Survey

Abstract

We present low-resolution near-infrared spectra of discoveries from an all-sky proper motion search conducted using multi-epoch data from the Wide-field Infrared Survey Explorer. Using the data from NEOWISE, along with the AllWISE catalog, Schneider et al. (2016) conducted an all-sky proper motion survey to search for nearby objects with high proper motions. Here, we present a follow-up spectroscopic survey of 65 of their discoveries, which focused primarily on potentially nearby objects (d < 25 pc), candidate late-type brown dwarfs (≥L7), and subdwarf candidates. We found 31 new M dwarfs, 18 new L dwarfs, and 11 new T dwarfs. Of these, 13 are subdwarfs, including one new sdL1 and two new sdL7s. Eleven of these discovereies, with spectral types ranging from M7 to T7 (including one subdwarf) are predicted to be within 25 pc, adding to the number of known objects in the solar neighborhood. We also discovered three new early-type T subdwarf candidates, one sdT1, one sdT2, and one sdT3, which would increase the number of known early-type T subdwarfs from two to five.

WISEA J041451.67–585456.7 and WISEA J181006.18–101000.5: The First Extreme T-type Subdwarfs?

“…As mentioned in Section 1, early-T type subdwarfs are rare and often show weak or ambiguous signs of low-metallicity, making comparisons to known early-T type subdwarfs challenging. To verify this, we compare in Figure 2 the spectra of WISEA 0414−5854 and WISEA 1810−1010 to that of the known esdL7 2MASS 05325346+8246465 (Burgasser et al 2003;Kirkpatrick et al 2010;Zhang et al 2017b) and to that of the suspected sdT3 WISEA 101944.62−391151.6 (Greco et al 2019). When compared to 2MASS 05325346+8246465, both WISEA 0414 −5854 and WISEA 1810−1010 have much deeper and broader absorption around 1.15 μm.…”

“…Even the tangential velocity estimates of these sources, estimated from spectral type-absolute magnitude relations, may be inaccurate for subdwarf types, depending on the band used. have identified a sample of T5 objects that could qualify as members of an sdT spectral class, while Greco et al (2019) have found three promising early-type sdT candidates. No members of more metal-poor esdT or usdT classes have yet been identified.…”

“…WISEA J181006.18−101000.5 (WISEA 1810−1010 hereafter) was initially identified as a potential high proper motion source as part of the NEOWISE proper motion survey (Schneider et al 2016;Greco et al 2019). However, at that time, its proper motion could not be confirmed because of the high density of background sources near this object (b  ≈4°.3) and the lack of additional detections at different epochs in other catalogs.…”

The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs

“…Eight objects were observed over the nights of 2018 April 1-3 and 2019 June 19 (UT) using the Astronomy Research with the Cornell Infra Red Imaging Spectrograph (ARCoIRIS) at the Victor Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory (CTIO), Chile. Instrument setup and data reductions are identical to those detailed in Greco et al (2019) and covered a spectral range of 0.8-2.4 μm at a resolving power of ∼3500.…”

New Candidate Extreme T Subdwarfs from the Backyard Worlds: Planet 9 Citizen Science Project

“…Figure 4 also provides a comparison against the sdT3 WISEA J101944.62−391151.6 (Schneider et al 2016;Greco et al 2019, hereafter WISEA 1019−3911). At K band, the WISEA 1553+6933 spectrum's amplitude and shape are slightly better matched by WISEA 1019−3911 than by any of the T-dwarf standards.…”