J/PASP/132/J4401 YSOs detection with W filter (Allers+, 2020)
A novel survey for young substellar objects with the W-band filter.
I. Filter design and new discoveries in Ophiuchus and Perseus.
Allers K.N., Liu M.C.
<Publ. Astron. Soc. Pac., 132, j4401 (2020)>
=2020PASP..132j4401A 2020PASP..132j4401A (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Photometry, infrared ; YSOs
Abstract:
We present the design and implementation of a medium-band near-IR
filter tailored for detecting low-mass stars and brown dwarfs from the
summit of Maunakea. The W-band filter is centered at 1.45µm with a
bandpass width of 6%, designed to measure the depth of the H2O water
absorption prominent in objects with spectral types of M6 and later.
When combined with standard J and H photometry, the W-band filter is
designed to determine spectral types to ~=1.4 subtypes for late-M and
L dwarfs, largely independent of surface gravity and reddening. This
filter's primary application is completing the census of young
substellar objects in star-forming regions, using W-band selection to
greatly reduce contamination by reddened background stars that impede
broad-band imaging surveys. We deployed the filter on the UH 88 inch
telescope to survey ∼3 degree2 of the NGC 1333, IC 348, and ρ
Ophiuchus star-forming regions. Our spectroscopic followup of W-band
selected candidates resulted in the confirmation of 48 ultracool
dwarfs with a success rate of 89%, demonstrating the efficacy of this
new filter and selection method.
Description:
To search for brown dwarfs in star-forming regions, we have designed
the W-band filter, a medium-bandpass filter centered at 1.45um. Our
W-band filter can be combined with broad-band J and H photometry to
create a reddening-insensitive index, Q.
We tested the efficacy of our filter by selecting candidate young
brown dwarfs based only on their Q values. Using SpeX, we
spectroscopically confirm 48/60 objects as having spectral types of M5
and later. If we include objects that met our selection criteria but
were already spectroscopically confirmed prior to our SpeX
observations, our confirmation rate is 95/107.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 45 81 Observing log: W band imaging
table4.dat 110 59 Photometry of observed brown dwarf candidates
table5.dat 95 58 IRTF/SpeX observing log
table6.dat 118 62 Classification of candidate members
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 10 F4.1 s RAs Right ascension (J2000)
12 A1 --- DE- Declination sign (J2000)
13- 14 I2 deg DEd Declination (J2000)
16- 17 I2 arcmin DEm Declination (J2000)
19- 20 I2 arcsec DEs Declination (J2000)
22- 31 A10 "date" Obs.date Observation date
33- 36 F4.2 --- secz Airmass
38- 41 F4.1 min Tint Integration time
43- 45 F3.1 arcsec Seeing Seeing
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Cluster Cluster name
11- 33 A23 --- Object Object name (UHW JDDD.ddddd+DD.ddddd)
35- 39 F5.2 mag Wmag W magnitude (lambdacenter=1.45um)
41- 44 F4.2 mag e_Wmag rms uncertainty on Wmag
46- 50 F5.2 mag JmagMKO ?=- MKO J magnitude
52- 55 F4.2 mag e_JmagMKO ? rms uncertainty on MKO J magnitude
57- 61 F5.2 mag HmagMKO ?=- MKO H magnitude
63- 66 F4.2 mag e_HmagMKO ? rms uncertainty on MKO H magnitude
68- 72 F5.2 mag JmagMASS ?=- 2MASS J magnitude
74- 77 F4.2 mag e_JmagMASS ? rms uncertainty on 2MASS J magnitude
79- 83 F5.2 mag HmagMASS ?=- 2MASS H magnitude
85- 88 F4.2 mag e_HmagMASS ? rms uncertainty on 2MASS H magnitude
90- 94 F5.2 --- QMKO ?=- MKO reddening-insensitive index (1)
96- 99 F4.2 --- e_QMKO ? rms uncertainty on MKO
reddening-insensitive index
101-105 F5.2 --- Q2MASS ?=- 2MASS reddening-insensitive index (1)
107-110 F4.2 --- e_Q2MASS ? rms uncertainty on 2MASS
reddening-insensitive index
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Note (1): we defined a reddening-independent index Q,
Q = J-W + e*(H-W), where
W refers to the magnitude of the object in our proposed filter,
J and H are magnitudes in the standard broad-band filters, and
e is the ratio of reddening color excesses, e=(AJ-AW)/(AW-AH).
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- Object Object name (UHW JDDD.ddddd+DD.ddddd)
25- 34 A10 "date" Obs.date UT observation date
36- 43 A8 --- Grat Gratting
45- 50 A6 arcsec Slit Slit (N.Nx15)
52- 55 I4 --- R Resolution
57- 60 F4.2 --- secz Airmass
62- 69 A8 s Nexpt Exposure time (NNxNNN.n)
71- 76 F6.1 s Tint Integration time
78- 80 I3 --- S/NY Median S/N of the spectrum within Y band
81 A1 --- --- [,]
83- 85 I3 --- S/NJ Median S/N of the spectrum within J band
86 A1 --- --- [,]
88- 90 I3 --- S/NH Median S/N of the spectrum within H band
91 A1 --- --- [,]
93- 95 I3 --- S/NK Median S/N of the spectrum within K band
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Cluster Cluster name (1)
11- 33 A23 --- Object Object name (UHW JDDD.ddddd+DD.ddddd)
35- 36 A2 --- SpType Spectral type
38- 42 F5.2 mag AV ?=- Absorption in V band
44- 47 F4.2 mag e_AV ?=- rms uncertainty on absorption in V band
48 A1 --- n_AV [a] Not eon AV (2)
50- 54 A5 --- Gravity [VL-G INT-G FLD-G]
57- 68 A12 --- SpTypeL Spectral type(s) from litterature
71- 83 A13 --- r_SpTypeL Reference(s) for spectra type (3)
85- 89 F5.2 mas Plx ? Gaia DR2 parallax
91- 94 F4.2 mas e_Plx ? rms uncertainty on Gaia DR2 parallax
96-101 F6.2 mas/yr pmRA ? Gaia DR2 proper motion along RA, pmRA*cosDE
103-106 F4.2 mas/yr e_pmRA ? rms uncertainty on pmRA
108-113 F6.2 mas/yr pmDE ? Gaia DR2 proper motion along DE
115-118 F4.2 mas/yr e_pmDE ? rms uncertainty on pmDE
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Note (1): When no obkect name, mean and standard deviation for Gaia DR2
parallaxes and proper motions are from Ortiz-Leon et al. (2018ApJ...865...73O 2018ApJ...865...73O,
Cat. J/ApJ/865/73) for IC 348 and NGC 1333 and Canovas et al.
(2019A&A...626A..80C 2019A&A...626A..80C, Cat. J/A+A/626/A80) for Ophiuchius.
Note (2): Reddening determined from J-H color rather than J-K, as K-band flux
is anomalously high relative to J and H. Luhman et al. (2016ApJ...827...52L 2016ApJ...827...52L)
interpret this as being scattered light from an edge-on disk.
Note (3): References as follows:
A10 = Alves de Oliveira et al. (2010A&A...515A..75A 2010A&A...515A..75A, Cat. J/A+A/515/A75)
A12 = Alves de Oliveira et al. (2012A&A...539A.151A 2012A&A...539A.151A)
A13 = Alves de Oliveira et al. (2013A&A...549A.123A 2013A&A...549A.123A)
G11 = Geers et al. (2011ApJ...726...23G 2011ApJ...726...23G)
L98 = Luhman et al. (1998ApJ...508..347L 1998ApJ...508..347L)
L12 = Luhman & Mamajek (2012ApJ...758...31L 2012ApJ...758...31L, Cat. J/ApJ/758/31)
L16 = Luhman et al. (2016ApJ...827...52L 2016ApJ...827...52L)
M12 = Muzic et al. (2012ApJ...744..134M 2012ApJ...744..134M, Cat. J/ApJ/744/134)
S06 = Slesnick et al. (2006AJ....131.3016S 2006AJ....131.3016S, Cat. J/AJ/131/3016)
S08 = Slesnick et al. (2008ApJ...688..377S 2008ApJ...688..377S, Cat. J/ApJ/688/377)
S09 = Scholz et al. (2009ApJ...702..805S 2009ApJ...702..805S)
S12 = Scholz et al. (2012ApJ...756...24S 2012ApJ...756...24S. Cat. J/ApJ/756/24)
W04 = Wilking et al. (2004AJ....127.1131W 2004AJ....127.1131W. Cat. J/AJ/127/1131)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Feb-2021