- ID:
- ivo://CDS.VizieR/J/ApJ/677/169
- Title:
- H{alpha} galaxies at z=0.84
- Short Name:
- J/ApJ/677/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an H{alpha} near-infrared narrowband survey searching for star-forming galaxies at redshift z=0.84. This work is an extension of our previous narrowband studies in the optical at lower redshifts. After removal of stars and redshift interlopers (using spectroscopic and photometric redshifts), we build a complete sample of 165 H{alpha} emitters in the extended Groth strip and GOODS-N fields with L(H{alpha})>10^41^ergs/s. We compute the H{alpha} luminosity function at z=0.84 after corrections for [NII] flux contamination, extinction, systematic errors, and incompleteness. Our sources present an average dust extinction of A(H{alpha})=1.5mag. Adopting H{alpha} as a surrogate for the instantaneous SFR, we measure an extinction-corrected SFR density of 0.17^+0.03^_-0.03_M_{sun}_/yr/Mpc^3^. Combining this result to our prior measurements at z=0.02, 0.24, and 0.40, we derive an H{alpha}-based evolution of the SFR density proportional to (1+z)^{beta}^ with {beta}=3.8+/-0.5. This evolution is consistent with that derived by other authors using different SFR tracers.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/123/2597
- Title:
- H{alpha} stars and HH objects near BRCs
- Short Name:
- J/AJ/123/2597
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Bright-rimmed clouds (BRCs) found in H II regions are probably sites of triggered star formation due to compression by ionization/shock fronts. Many BRCs harbor IRAS point sources of low dust temperature. They also frequently contain a small cluster of near-IR stars that is elongated along the axis of the BRC. Here we present the results of our H{alpha} grism spectroscopy and narrowband imaging observations of BRCs in search of candidate premain-sequence stars of the T Tauri, Herbig Ae/Be and related types, and Herbig-Haro (HH) objects. We have detected a large number (460) of H{alpha} emission stars down to a limiting magnitude of about R=20 in and around all but two of the 28 BRCs observed. The present study has, for the first time, reached down nearly to the faintest classical T Tauri star population in OB associations. A total of 12 new HH objects have been found.
- ID:
- ivo://CDS.VizieR/J/AJ/135/2323
- Title:
- H{alpha} stars and HH objects near BRCs
- Short Name:
- J/AJ/135/2323
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out near-IR/optical observations to examine star formation toward a bright-rimmed cometary globule (BRC37) facing the exciting star(s) of an HII region (IC1396) containing an IRAS source, which is considered to be an intermediate-mass protostar. With slitless spectroscopy we detected ten H{alpha} emission stars around the globule, six of which are near the tip of the globule and are aligned along the direction to the exciting stars.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A64
- Title:
- H and K-band stacked spectra of U/LIRGs
- Short Name:
- J/A+A/546/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an atlas of a sample of local (z<0.1) LIRGs (10) and ULIRGs (7) covering the luminosity range log(L_IR_\L_{sun}_)=11.1-12.4. The atlas is based on near-infrared H (1.45-1.85um) and K-band (1.95-2.45um) VLT-SINFONI integral field spectroscopy. The atlas presents the ionised, partially ionised, and warm molecular gas 2D flux distributions and kinematics over a FoV of ~3x3kpc (LIRGs) and ~12x12kpc (ULIRGs) and with average linear resolutions of ~0.2kpc and ~0.9kpc, respectively. The different phases of the gas show a wide morphological variety with the nucleus as the brightest Br_g source for ~33% of the LIRGs and ~71% of the ULIRGs, whereas all the LIRGs and ULIRGs have their maximum H_2_ emission in their nuclear regions. In LIRGs, the ionised gas distribution is dominated by the emission from the star-forming rings or giant HII regions in the spiral arms. The Br_g_ and [FeII] line at 1.644um trace the same structures, although the emission peaks at different locations in some of the objects, and the [FeII] seems to be more extended and diffuse. The ULIRG subsample is at larger distances and contains mainly pre-coalescence interacting systems. Although the peaks of the molecular gas emission and the continuum coincide in ~71% of the ULIRGs, regions with intense Pa_a_ (Br_g_) emission tracing luminous star-forming regions located at distances of 2-4kpc away from the nucleus are also detected, usually associated with secondary nuclei or tidal tails. LIRGs have mean observed (i.e. uncorrected for internal extinction) SFR surface densities of about 0.4 to 0.9M_{sun}_/yr/kpc^2^ over large areas (4-9kpc^2^) with peaks of about 2-2.5M_{sun}_/yr/kpc^2^ in the smaller regions (0.16kpc^2^) associated with the nucleus of the galaxy or the brightest Br_g_ region. ULIRGs do have similar average SFR surface densities for the integrated emitting regions of ~0.4M_{sun]_/yr/kpc^2^ in somewhat larger areas (100-200kpc^2^) and for the Pa_a peak (~2M_{sun}_/yr/kpc^2^ in 4kpc^2^). The observed gas kinematics in LIRGs is primarily due to rotational motions around the centre of the galaxy, although local deviations associated with radial flows and/or regions of higher velocity dispersions are present. The ionised and molecular gas share the same kinematics (velocity field and velocity dispersion) to first order, showing slight differences in the velocity amplitudes (peak-to-peak) in some cases, whereas the average velocity dispersions are compatible within uncertainties. As expected, the kinematics of the ULIRG subsample is more complex, owing to the interacting nature of the objects of the sample.
- ID:
- ivo://CDS.VizieR/J/A+A/559/L2
- Title:
- H and Ks maps aroung G045.47+0.05
- Short Name:
- J/A+A/559/L2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a continuation of a previous work, in which we found strong evidence of massive molecular outflows towards a massive star forming site, we present a new study of this region based on very high angular resolution observations with the aim of discovering the outflow driven mechanism. Using near-IR data acquired with Gemini-NIRI at the broad H- and Ks-bands, we study a region of 22"x22" around the UCHII region G045.47+0.05, a massive star forming site at the distance of about 8kpc. To image the source with the highest spatial resolution possible we employed the adaptative optic system ALTAIR, achieving an angular resolution of about 0.15". We discovered a cone-like shape nebula with an opening angle of about 90{deg} extending eastwards the IR source 2MASS J19142564+1109283, a very likely MYSO. This morphology suggests a cavity that was cleared in the circumstellar material and its emission may arise from scattered continuum light, warm dust, and likely emission lines from shock-excited gas. The nebula, presenting arc-like features, is connected with the IR source through a jet-like structure, which is aligned with the blue shifted CO outflow found in a previous study. The near-IR structure lies ~3" north of the radio continuum emission, revealing that it is not spatially coincident with the UCHII region. The observed morphology and structure of the near-IR nebula strongly suggest the presence of a precessing jet. In this study we have resolved the circumstellar ambient (in scale of a thousand A.U.) of a distant MYSO, indeed one of the farthest cases.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/65
- Title:
- H-ATLAS search for strongly lensed galaxies
- Short Name:
- J/ApJ/749/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While the selection of strongly lensed galaxies (SLGs) with 500{mu}m flux density S_500_>100mJy has proven to be rather straightforward, for many applications it is important to analyze samples larger than the ones obtained when confining ourselves to such a bright limit. Moreover, only by probing to fainter flux densities is it possible to exploit strong lensing to investigate the bulk of the high-z star-forming galaxy population. We describe HALOS (the Herschel-ATLAS Lensed Objects Selection), a method for efficiently selecting fainter candidate SLGs, reaching a surface density of =~1.5-2/deg^2^, i.e., a factor of about 4-6 higher than that at the 100mJy flux limit. HALOS will allow the selection of up to ~1000 candidate SLGs (with amplifications {mu}>~2) over the full H-ATLAS survey area. Applying HALOS to the H-ATLAS Science Demonstration Phase field (=~14.4deg^2^) we find 31 candidate SLGs, whose candidate lenses are identified in the VIKING near-infrared catalog. Using the available information on candidate sources and candidate lenses we tentatively estimate a =~72% purity of the sample. As expected, the purity decreases with decreasing flux density of the sources and with increasing angular separation between candidate sources and lenses. The redshift distribution of the candidate lensed sources is close to that reported for most previous surveys for lensed galaxies, while that of candidate lenses extends to redshifts substantially higher than found in the other surveys. The counts of candidate SLGs are also in good agreement with model predictions. Even though a key ingredient of the method is the deep near-infrared VIKING photometry, we show that H-ATLAS data alone allow the selection of a similarly deep sample of candidate SLGs with an efficiency close to 50%; a slightly lower surface density (=~ 1.45/deg2) can be reached with a ~70% efficiency.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/19
- Title:
- Hawaii Infrared Parallax Program. I.
- Short Name:
- J/ApJS/201/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Astrometry and photometry for 318 ultracool dwarfs in 265 systems that have measured trigonometric parallaxes. To be included in this tabulation, an object must have a spectral type >=M6 or a K-band absolute magnitude >8.5mag. Parallaxes, proper motions, and coordinates at a specified epoch are given for all objects. Photometric measurements in MKO, 2MASS, Spitzer, and WISE systems are given when available. Various other flags that provide additional information about the object or photometry are included.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/1734
- Title:
- HAWK-I JHK photometry of the Orion Nebula Cloud
- Short Name:
- J/MNRAS/461/1734
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Due to its youth, proximity and richness, the Orion nebula cloud (ONC) is an ideal testbed to obtain a comprehensive view on the initial mass function (IMF) down to the planetary mass regime. Using the HAWK-I camera at the VLT, we have obtained an unprecedented deep and wide near-infrared JHK mosaic of the ONC (90 per cent completeness at K ~19.0mag, 22x28 arcmin^2^). Applying the most recent isochrones and accounting for the contamination of background stars and galaxies, we find that ONC's IMF is bimodal with distinct peaks at about 0.25 and 0.025M_{sun}_ separated by a pronounced dip at the hydrogen burning limit (0.08M_{sun}_), with a depth of about a factor of 2-3 below the log-normal distribution. Apart from ~920 low-mass stars (M<1.4M_{sun}_) the IMF contains ~760 brown dwarf candidates and ~160 isolated planetary mass object candidates with M>0.005M_{sun}_, hence about 10 times more substellar candidates than known before. The substellar IMF peak at 0.025M_{sun}_ could be caused by brown dwarfs and isolated planetary mass objects which have been ejected from multiple systems during the early star formation process or from circumstellar discs.
- ID:
- ivo://CDS.VizieR/J/A+A/470/957
- Title:
- H-band images of IRAS 19312+1950
- Short Name:
- J/A+A/470/957
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained H-band polarimetric data of IRAS 19312+1950 using the near-infrared camera (CIAO) on the 8m Subaru telescope. In order to investigate the physical properties of the central star and the nebula, we performed dust radiative transfer modeling and compared the model results with the observed spectral energy distributions (SEDs), the radial profiles of the total intensity image, and the fraction of linear polarization map. The total intensity image shows a nearly spherical core with ~3" radius, an S-shaped arm extending ~10" in the northwest to southeast direction, and an extended lobe towards the southwest. The polarization map shows a centro-symmetric vector alignment in almost the entire nebula and low polarizations along the S-shaped arm. These results suggest that the nebula is accompanied by a central star, and the S-shaped arm has a physically ring-like structure. From our radiative transfer modeling, we estimated the stellar temperature, the bolometric luminosity, and the current mass-loss rate to be 2800K, 7000L_{sun}_, and 5.3x10^-6^M_{sun}_/yr, respectively. Taking into account previous observational results, such as the detection of SiO maser emissions and silicate absorption feature in the 10{mu}m spectrum, our dust radiative transfer analysis based on our NIR imaging polarimetry suggests that (1) the central star of IRAS 19312+1950 is likely to be an oxygen-rich, dust-enshrouded AGB star and (2) most of the circumstellar material originates from other sources (e.g. ambient dark clouds) rather than as a result of mass loss from the central star.
- ID:
- ivo://CDS.VizieR/J/A+A/403/493
- Title:
- H-band observation of Chandra Deep Field South
- Short Name:
- J/A+A/403/493
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report preliminary results of our H-band survey of the Chandra Deep Field South (CDFS). The observations were made using SofI on the NTT, and cover 0.027 square degrees with a 50% completeness limit of H=20.5, and 0.17 square degrees with a 50% completeness limit of H=19.8. We used SExtractor to extract sources from our fields. In total we have detected 4819 objects. Star-galaxy separation was performed using the SExtractor parameter "stellarity index". All objects with an index of 0.5 or lower were classified as galaxies. According to this criterion, 80% of our detections are galaxies. We then compare our results with previous observations of the CDFS. Our astrometric solutions are in good agreement with the Las Campanas Infrared Survey (LCIRS), the COMBO-17 and the ESO-EIS surveys. The photometry of our catalog compares satisfactorily with the results of the LCIRS, as well as with the GOODS data. Galaxy number counts are presented and compared with the LCIRS results. The present data are intended to complement the recent and future multi-wavelength observations of the CDFS and will be used, in conjunction with additional multiband photometry, to find counterparts of the upcoming mid-infrared surveys with SIRTF.