J/A+A/698/A96 R CrA very low-mass objects JHK magnitudes (Kanai+, 2025)
A deep NIR survey of very low-mass objects in the R CrA region.
Kanai T., Oasa Y.
<Astron. Astrophys. 698, A96 (2025)>
=2025A&A...698A..96K 2025A&A...698A..96K (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Stars, pre-main sequence ;
Photometry, infrared
Keywords: brown dwarfs - stars: formation - stars: low-mass -
stars: luminosity function, mass function - stars: pre-main sequence
Abstract:
Our aim is to identify the population of very low-mass object (VLMO)
candidates in the R CrA region and reveal their formation dependence
in the local environments.
We performed a deep near-infrared (NIR) photometric observation of the
R CrA region by UKIRT/WFCAM. Class I and II candidates showing NIR
excess were selected from their observed colors. We derived the
photometric mass of each candidate with an age assumption of 1Myr. We
compared the derived mass of identified VLMO candidates to the dust
column density at their position.
The 10σ limiting magnitudes were 20.7, 19.6, and 19.2mag in the
J-, H-, and K-band, respectively, and we detected 2922 JHK sources in
all three bands with an S/N greater than ten in the K-band. Fifteen
Class I and 207 Class II candidates with NIR excess were selected from
a [J-H]/[H-K] color-color diagram. Six low-mass stars, five brown
dwarfs, and 196 planetary-mass object candidates were identified from
the J-band luminosity of Class II candidates with the age assumption
of 1 Myr using the evolutionary models. The derived initial mass
function (IMF) does not appear to decrease in the brown dwarf and
planetary-mass regime, even when taking into account the background
star and galactic contamination. From comparison between the spatial
distributions of Class I and II candidates and dust column densities
derived from the Herschel observation, we found that all the low-mass
star and brown dwarf candidates are located in the region where the
dust column densities are higher than 2.5x1021cm-2, while
planetary-mass object candidates are independent of their local dust
densities. Our results suggest that the formations of low-mass stars
and very low-mass objects may be dependent on the local cloud
properties.
Description:
The JHK catalog of identified objects in the R CrA region with SN>10
at K-band and SN>3 at J- and H-band.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 101 2922 JHK catalog of identified objects in the R CrA
region with SN>10 at K-band and SN>3 at
J- and H-band
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID [1/2922] Object ID
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 35 F6.3 --- Jmag WFCAM J magnitude
37- 41 F5.3 --- e_Jmag WFCAM J magnitude error
43- 48 F6.3 --- Hmag WFCAM H magnitude
50- 54 F5.3 --- e_Hmag WFCAM H magnitude error
56- 61 F6.3 --- Kmag WFCAM K magnitude
63- 67 F5.3 --- e_Kmag WFCAM K magnitude error
69- 74 F6.3 mag J0mag ?=- J0 magnitude
76 I1 --- Class [1/4] Object Classification (1)
78- 88 E11.5 cm-2 N Herschel dust column density from HGBS
90- 99 A10 --- Name SIMBAD name
101 A1 --- Ref Reference number (2)
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Note (1): Classification flag of each source as follows:
1 = Class I candidate
2 = Class II candidate
3 = background star/Class III candidate
4 = Object below the CTTS locus on color-color diagram
Note (2): References as follows:
1 = Taylor & Storey (1984MNRAS.209p...5T 1984MNRAS.209p...5T)
2 = Wilking et al. (1997AJ....114.2029W 1997AJ....114.2029W)
3 = Olofsson et al. (1999A&A...350..883O 1999A&A...350..883O, Cat. J/A+A/350/883)
4 = Forbrich & Preibisch (2007A&A...475..959F 2007A&A...475..959F, Cat. J/A+A/475/959)
5 = Choi et al. (2009ApJ...690.1901C 2009ApJ...690.1901C)
6 = Haas et al. (2008A&A...488..987H 2008A&A...488..987H, Cat. J/A+A/488/987)
7 = Gutermuth et al. (2009ApJS..184...18G 2009ApJS..184...18G, Cat. J/ApJS/184/18)
8 = Peterson et al. (2011ApJS..194...43P 2011ApJS..194...43P, Cat. J/ApJS/194/43)
9 = Esplin & Luhman (2022AJ....163...64E 2022AJ....163...64E, Cat. J/AJ/163/64)
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Acknowledgements:
T. Kanai, s15pp223(at)gmail.com
(End) Patricia Vannier [CDS] 23-Apr-2025