- ID:
- ivo://CDS.VizieR/J/ApJS/147/305
- Title:
- IUE atlas of pre-main-sequence stars
- Short Name:
- J/ApJS/147/305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identified 137 T Tauri stars (TTS) and 97 Herbig Ae/Be (HAEBE) stars observed by IUE in the wavelength interval 1900-3200{AA}. Each low-resolution (R~6{AA}) spectrum was visually inspected for source contamination and data quality, and then all usable spectra were combined to form a single time averaged spectrum for each star. For sources with multiple observations, we characterized variability and compared with previously published amplitudes at shorter wavelengths. We combined several co-added spectra of diskless TTS to produce a pair of intrinsic stellar spectra unaffected by accretion. We then fitted spectra of TTS with the reddened sum of an intrinsic spectrum and a schematic veiling continuum, measuring emission line fluxes from the residuals. We used extinction and distance estimates from the literature to convert measured Mg II line fluxes into intrinsic line luminosities, noting that the IUE detection limit introduces a sample bias such that intrinsic line luminosity is correlated with extinction. This sample bias complicates any physical interpretation of TTS intrinsic luminosities. We measured extinction toward HAEBE stars by fitting our co-added IUE spectra with reddened spectra of main-sequence stars and also from V band minus 3000{AA} color excess. We measured excess line emission and absorption in spectra of HAEBE stars divided by fitted spectra of main-sequence stars, noting that HAEBE stars with an infrared excess indicating circumstellar material typically also have anomalous UV line strengths. In the latter situation, Mg II is usually shallower than in a main-sequence star of the same spectral class, whereas Fe II lines are equally likely to be deeper or shallower. Our co-added spectra of TTS, HAEBE stars, and main-sequence templates are available electronically, in FITS and ASCCI format, at http://archive.stsci.edu/prepds/iuepms/ .
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/392/1034
- Title:
- IZJHKL' photometry of NGC 6611
- Short Name:
- J/MNRAS/392/1034
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 6611 is the massive young cluster (2-3Myr) that ionizes the Eagle Nebula. We present very deep photometric observations of the central region of NGC 6611 obtained with the Hubble Space Telescope and the following filters: ACS/WFC F775W and F850LP and NIC2 F110W and F160W, loosely equivalent to ground-based IZJH filters. This survey reaches down to I~26mag. We construct the initial mass function (IMF) from ~1.5M_{sun}_ well into the brown dwarf regime (down to ~0.02M_{sun}_). We have detected 30-35 brown dwarf candidates in this sample. The low-mass IMF is combined with a higher-mass IMF constructed from the ground-based catalogue from Oliveira et al. We compare the final IMF with those of well-studied star-forming regions: we find that the IMF of NGC 6611 more closely resembles that of the low-mass star-forming region in Taurus than that of the more massive Orion Nebula Cluster. We conclude that there seems to be no severe environmental effect in the IMF due to the proximity of the massive stars in NGC 6611.
- ID:
- ivo://CDS.VizieR/J/AJ/121/974
- Title:
- JHK photometry in Cha I
- Short Name:
- J/AJ/121/974
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a near-infrared imaging survey covering ~1deg^2^ of the Chamaeleon I dark cloud. The survey is complete for K<15.0, H<16.0, and J<16.5, roughly 2 magnitudes more sensitive than previous large-scale surveys. We use the large number of background stars detected to derive an accurate near-infrared extinction law for the cloud and select new candidate members with near-infrared color excesses. We list ~100 candidates of the cloud with K>=2.0, based on their positions in the J-H, H-K color-color diagram. These new stars have low luminosities (K~12-16, H-K>~0.5-1.5) and may have masses close to or even below the hydrogen-burning limit.
- ID:
- ivo://CDS.VizieR/J/MNRAS/359/2
- Title:
- JHK photometry in G173.58+2.45
- Short Name:
- J/MNRAS/359/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-epoch infrared photometric study of the intermediate-mass star-forming region G173.58+2.45. Photometric observations are obtained using the near-infrared JHKL'M' filters and narrow-band filters centred at the wavelengths of the H_2_(1-0)S(1)(2.122um) and [FeII](1.644um) lines. The H2 image shows molecular emission from shocked gas, implying the presence of multiple star formation and associated outflow activity. We see evidence for several collimated outflows.
- ID:
- ivo://CDS.VizieR/J/AJ/131/951
- Title:
- JHK photometry in the direction of RCW 121
- Short Name:
- J/AJ/131/951
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report near-infrared (NIR) broadband and narrowband photometric observations in the direction of the IRAS 17149-3916 source that reveal the presence of a young cluster of massive stars embedded in an HII region coincident with RCW 121. These observations, together with published radio data and Midcourse Space Experiment and Spitzer images, were used to determine some of the physical parameters of the region. We found 96 cluster member candidates in an area of about 1.5x2.0arcmin^2^, 30% of them showing excess emission in the near-IR.
- ID:
- ivo://CDS.VizieR/J/ApJ/602/850
- Title:
- JHK' photometry near IRAS 18507+0121
- Short Name:
- J/ApJ/602/850
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed the massive star-forming region IRAS 18507+0121 at millimeter wavelengths in 3mm continuum emission, H^13^CO+ (J=1-0) and SiO (v=0,J=2-1) line emission, and at near-infrared (NIR) wavelengths between 1.2 and 2.1{mu}m. Two compact molecular cores are detected: one north and one south, separated by ~40". The northern molecular core contains a newly discovered, deeply embedded, B2 protostar surrounded by several hundred solar masses of warm gas and dust, G34.4+0.23 MM. Based on the presence of warm dust emission and the lack of detection at NIR wavelengths, we suggest that G34.4+0.23 MM may represent the relatively rare discovery of a massive protostar (e.g., analogous to a low-mass "Class 0" protostar). The southern molecular core is associated with an NIR cluster of young stars and an ultracompact HII region, G34.4+0.23, with a central B0.5 star. The fraction of NIR stars with excess infrared emission indicative of circumstellar material is greater than 50%, which suggests an upper limit on the age of the IRAS 18507+0121 star-forming region of 3Myr.
- ID:
- ivo://CDS.VizieR/J/AJ/121/3160
- Title:
- JHK photometry near the Trapezium region
- Short Name:
- J/AJ/121/3160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of J, H, and Ks time-series photometry obtained with the southern 2MASS telescope over a 0.84{deg}x6{deg} region centered near the Trapezium region of the Orion Nebula cluster. These data are used to establish the near-infrared variability properties of premain-sequence stars in Orion on timescales of ~1-36days, ~2 months, and ~2 years. A total of 1235 near-infrared variable stars are identified, ~93% of which are likely associated with the Orion A molecular cloud.
- ID:
- ivo://CDS.VizieR/J/MNRAS/361/211
- Title:
- JHK photometry of brown dwarfs in Orion
- Short Name:
- J/MNRAS/361/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a deep near-infrared (JHK) survey of the outer parts of the Trapezium Cluster with Gemini South/Flamingos. 396 sources were detected in a 26-arcmin^2^ area, including 138 brown dwarf candidates, defined as M<0.075M_{sun}_ for an assumed age of 1Myr. Only 33 of the brown dwarf candidates are planetary mass candidates with estimated masses in the range 0.003<M<0.012M_{sun}_. In an extinction-limited sample (AV<5) complete to approximately 0.005M_{sun}_ (5M_Jup_) the mass function appears to drop by a factor of 2 at the deuterium burning threshold, i.e. at planetary masses. After allowing for background contamination it is likely that planetary mass objects at 3-13M_Jup_ number <10% of the cluster population, with an upper limit of 13%. Analysis of the spatial distribution of stars and brown dwarf candidates suggests that brown dwarfs and very low-mass stars (M<0.1M_{sun}_) are less likely than more massive stars to have wide (>150AU) binary companions.
- ID:
- ivo://CDS.VizieR/J/A+A/399/147
- Title:
- JHK photometry of C-cloud IRAS sources
- Short Name:
- J/A+A/399/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of NIR (JHK) photometry for about 1000 stars in 10 fields around IRAS sources previously recognized as related to star forming sites in the Vela Molecular Ridge C and D clouds. Only objects at least detected in the K band are listed. IRAS sources are indicated by the short designation adopted in the Paper (# IRS). Due to the presence of bad pixels or because of the closeness to the image edge, photometry could not be performed on a few objects and in such cases magnitudes and errors are not given at all. Note that, for IRS 33, coordinates are offsets (in arcsec) from source # 4.
- ID:
- ivo://CDS.VizieR/J/ApJ/672/398
- Title:
- JHK' photometry of M17 silhouette object
- Short Name:
- J/ApJ/672/398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To study how the structure of the envelopes of young stellar objects (YSOs) evolve, we carried out a deep JHK'-band imaging survey of the M17 star-forming region using a near-infrared camera and the Infrared Camera and Spectrograph with adaptive optics mounted on the Subaru Telescope. In this survey, we found 51 dark silhouettes against bright near-infrared nebula emissions as background lights. They are regarded as envelopes associated with YSOs due to their size and association with the YSOs. We derived size, morphology, extinction, and mass for each silhouette envelope.
