J/AJ/143/61 Hα spectroscopy in IC 1396 HII region (Nakano+, 2012)
Wide-field survey of emission-line stars in IC 1396.
Nakano M., Sugitani K., Watanabe M., Fukuda N., Ishihara D., Ueno M.
<Astron. J., 143, 61 (2012)>
=2012AJ....143...61N 2012AJ....143...61N
ADC_Keywords: H II regions ; Stars, emission ; Stars, pre-main sequence ;
Spectroscopy ; Photometry, infrared ; Cross identifications
Keywords: H II regions - ISM: individual: (IC 1396) -
open clusters and associations: individual: (Trumpler 37) -
stars: formation - stars: pre-main sequence
Abstract:
We have made an extensive survey of emission-line stars in the IC 1396
H II region to investigate the low-mass population of
pre-main-sequence (PMS) stars. A total of 639 Hα emission-line
stars were detected in an area of 4.2deg2 and their i' photometry
was measured. Their spatial distribution exhibits several aggregates
near the elephant trunk globule (Rim A) and bright-rimmed clouds at
the edge of the H II region (Rim B and SFO 37, 38, 39, 41), and near
HD206267, which is the main exciting star of the HII region. Based on
the extinction estimated from the near-infrared color-color diagram,
we have selected PMS star candidates associated with IC1396. The age
and mass were derived from the extinction-corrected color-magnitude
diagram and theoretical PMS tracks. Most of our PMS candidates have
ages of <3Myr and masses of 0.2-0.6M☉. Although it appears that
only a few stars were formed in the last 1Myr in the east region of
the exciting star, the age difference among subregions in our surveyed
area is not clear from the statistical test. Our results may suggest
that massive stars were born after the continuous formation of
low-mass stars for 10Myr. The birth of the exciting star could be the
late stage of slow but contiguous star formation in the natal
molecular cloud. It may have triggered the formation of many low-mass
stars at the dense inhomogeneity in and around the HII region by a
radiation-driven implosion.
Description:
Slitless grism spectroscopic searches for Hα emission objects in
IC 1396 were conducted in 2004 and between 2006 and 2009 using the
Wide Field Grism Spectrograph 2 (WFGS2) at the f/10 Cassegrain focus
of the University of Hawaii (UH) 2.2m telescope on Mauna Kea.
The whole IC 1396 region was covered by 157 field positions including
overlapping areas. For each field, we have taken a single 30 s
exposure in the direct mode with a wide Hα filter. Direct images
with an i'-band filter were also taken with WFGS2 in 2008 August and
2009 August.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 146 639 List of emission-line stars in IC 1396
refs.dat 150 16 References
--------------------------------------------------------------------------------
See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
III/227 : General Catalog of galactic Carbon stars, 3d Ed. (Alksnis+ 2001
III/256 : Vatican Emission-line stars (Coyne+ 1974-1983)
J/MNRAS/415/103 : IPHAS T Tauri candidates in IC 1396 (Barentsen+, 2011)
J/AJ/135/2323 : Hα stars and HH objects near BRCs (Ikeda+, 2008)
J/ApJ/654/316 : X-ray sources in IC 1396N (Getman+, 2007)
J/ApJ/638/897 : IR photometry in Tr 37 and NGC 7160 (Sicilia-Aguilar+, 2006)
J/AJ/132/2135 : Spectroscopy in Tr 37 (Sicilia-Aguilar+, 2006)
J/AJ/130/188 : Young stars in Tr 37 & NGC 7160 (Sicilia-Aguilar+, 2005)
J/AJ/128/805 : Low-mass stars in the Cep OB2 region (Sicilia-Aguilar+ 2004)
J/AJ/123/2597 : Hα stars and HH objects near BRCs (Ogura+, 2002)
J/A+A/309/581 : CO observations of clouds in IC 1396 region (Weikard +, 1996)
J/A+AS/112/35 : Emission lines from giant HII regions (Garcia Vargas+, 1995)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/639] Running sequence number
(<[NSW2012] NNN> in Simbad)
5- 6 I2 h RAh [21] Hour of Right Ascension (J2000)
8- 9 I2 min RAm [30/48] Minute of Right Ascension (J2000)
11- 14 F4.1 s RAs Second of Right Ascension (J2000)
16 A1 --- DE- [+] Sign of the declination
17- 18 I2 deg DEd [56/58] Degree of Declination (J2000)
20- 21 I2 arcmin DEm Arcminute of Declination (J2000)
23- 26 F4.1 arcsec DEs Arcsecond of Declination (J2000)
28- 32 F5.2 mag i'mag [13.63/19.79]? The WFGS2 i' band AB magnitude
34 A1 --- f_i'mag [s-] i'mag satured (s) or of low quality (-)
36- 38 I3 0.1nm EW [0/512]? Equivalent width of Hα emission;
in Angstroms
40- 55 A16 --- 2MASS 2MASS identifier of the near-IR counterpart.
(HHMMSSss+DDMMSSd; J2000) (1)
57- 58 A2 --- f_2MASS [6x g] Note on 2MASS counterpart (1)
60- 62 A3 --- q_2MASS 2MASS photometric quality (2)
64- 68 F5.2 mag Jmag [8.51/17.39]? 2MASS J band magnitude
70- 73 F4.2 mag J-H [0.15/2.13]? 2MASS (J-H) color index
75- 79 F5.2 mag H-K [-0.23/1.98]? 2MASS (H-Ks) color index
81- 84 F4.2 mag Av [0.06/9.52]? The V band extinction Av (3)
86 A1 --- C* [f] f: Carbon star candidate flag (3 objects)
88-146 A59 --- Notes Identification in the literature/comments (4)
--------------------------------------------------------------------------------
Note (1): We compared our list of emission stars with the 2MASS point-source
catalog (Cat. II/246) with 12 stars supplemented by the 2MASS 6x
point-source catalog (Cat. II/281). The flag means:
6x = represents the 2MASS 6x Point Star Catalog (Cat. II/281).
g = due to small separation angles or positional uncertainties,
two pairs of Hα stars are identified with a single 2MASS source
(Seq. 250/251 and Seq. 600/601).
Note (2): After comparison (see Note (2)), we found matches for 617 stars
with 2MASS stars within 2" and determined that 548 of these have
good quality JHKs photometry (quality flag AAA).
Note (3): Calculated from the NIR color-color diagram (see Section 4.1).
Note (4): About 70% of our Hα stars cannot be identified with known
sources in the SIMBAD database; see the "refs.dat" file for
identification in the literature.
The "Class" of object (Class-I (I), Class-II (II), Class-III (III),
transition object (TO), Herbig Ae/Be star (HAeBe)), mainly from
Sicilia-Aguilar et al. (2006, Cat. J/AJ/132/2135), are shown in
parenthesis.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Ref Reference code
8- 26 A19 --- BibCode Bibliographic code
28- 49 A22 --- Aut Author's name
51-150 A100 --- Com Comments
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 26-Apr-2013