- ID:
- ivo://CDS.VizieR/J/AJ/143/3
- Title:
- H{alpha} emission stars in IC 1274
- Short Name:
- J/AJ/143/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IC 1274 is a faintly luminous nebula lying on the near surface of the Lynds 227 (L227) molecular cloud. Its cavity-like morphology is reminiscent of a blistered star-forming region. Four luminous, early-type (B0-B5) stars are located within a spherical volume ~5' in diameter that appears to be clear of heavy obscuration. Approximately centered in the cleared region is the B0 V star HD 166033, which is thought to be largely responsible for the cavity's excavation. Over 80 H{alpha} emission sources brighter than V~21 have been identified in the region. More than half of these are concentrated in IC 1274 and are presumably members of a faint T Tauri star population. Chandra Advanced CCD Imaging Spectrometer imaging of a nearby suspected pulsar and time-variable {gamma}-ray source (GeV J1809-2327) detected 21 X-ray sources in the cluster vicinity, some of which are coincident with the early-type stars and H{alpha} emitters in IC 1274. Deep (V~22) optical BVRI photometry has been obtained for the cluster region. A distance of 1.82+/-0.3kpc and a mean extinction of AV~1.21+/-0.2mag follow from photometry of the early-type stars. Using pre-main-sequence evolutionary models, we derive a median age for the H{alpha} emitters and X-ray sources of ~1Myr; however, a significant dispersion is present. The displaced material was driven against what remains of the molecular cloud to the east, enabling the formation of the substantial number of T Tauri stars found there. A dispersed population of H{alpha} emitters is also found along the periphery of L227, IC 1275, and IC 4684.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/131/1530
- Title:
- H{alpha} emission stars in LDN988
- Short Name:
- J/AJ/131/1530
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- L988 is a large (~0.5{deg}x0.7{deg}) dark cloud complex at about 600pc that contains several bright pre-main-sequence objects (such as V1331 Cyg and LkH{alpha} 321), but this paper deals in detail only with a small region on its eastern edge, near the HAeBe star LkH{alpha} 324. That star and its distant companion LkH{alpha} 324SE lie at the apex of a V-shaped area apparently excavated from the edge of L988, and are the brightest members of a small cluster containing about 50 H{alpha}-emission stars.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1805
- Title:
- H{alpha} emission stars in NGC 2362
- Short Name:
- J/AJ/130/1805
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An H{alpha} emission survey of the young cluster NGC 2362 resulted in the detection of 130 H{alpha} emission stars in an 11'x11' field approximately centered on the fourth magnitude O9 Ib multiple star {tau} CMa. The survey was carried out using the wide-field grism spectrograph on the University of Hawaii 2.2m telescope and the Gemini Multi-Object Spectrograph (GMOS) on Gemini North. Deep optical VR_C_I_C_ (to V~23.0) and near-infrared (NIR) photometry (JHK) to K~16 were obtained for several fields within the cluster. Spectra covering the 6000-8000{AA} region at a resolution of R~3000 (adequate for the determination of LiI{lambda}6708 line strengths) were also acquired for ~200 pre-main-sequence (PMS) candidates with GMOS.
- ID:
- ivo://CDS.VizieR/J/AJ/129/829
- Title:
- H{alpha} emission stars in NGC 2264
- Short Name:
- J/AJ/129/829
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An H{alpha} emission survey of the young cluster NGC 2264 in the Mon OB1 association resulted in the detection of 490 H{alpha} emission stars in a 25'x40' field approximately centered between the O7 V multiple star S Mon and the Cone Nebula. The survey was carried out with the wide-field grism spectrograph (WFGS) on the University of Hawaii 2.2m telescope on Mauna Kea. X-ray observations made with the European Photon Imaging Camera (EPIC) on board the European Space Agency's XMM-Newton satellite observatory will be discussed in a subsequent paper. Optical (BVR_C_I_C_) photometry was obtained for selected fields to supplement similar data from the literature. Spectra covering the 6000-8000{AA} region at a resolution of R~3000 (adequate for the determination of Li I {lambda}6708 line strengths) were obtained for 150 H{alpha} and X-ray emission sources with the Gemini Multi-Object Spectrograph (GMOS).
- ID:
- ivo://CDS.VizieR/II/309
- Title:
- H{alpha} emission stars in the Orion Nebula
- Short Name:
- II/309
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog of 534 H{alpha} emission lines stars in the region of the Orion Nebula (5{deg}x5{deg}) is presented, an the basis of 240 "new" H{alpha} stars found on Tonantzintla spectral plates and previous known H{alpha} emission stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/416/2041
- Title:
- H{alpha} emitters at z=2.23
- Short Name:
- J/MNRAS/416/2041
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a narrow-band (H_2_S1, {lambda}_c_=2.121um, {delta}{lambda}=0.021um) imaging search with Wide Field Camera/United Kingdom Infrared Telescope for H{alpha} emitters (HAEs) around several potential signposts of rare (~10^-7^-10^-8^ comoving Mpc^-3^) overdense regions at z=2.23: an overdensity of quasi-stellar objects [QSOs; 2dF QSO Redshift Survey (2QZ) cluster], a powerful, high-redshift radio galaxy (HzRG) and a concentration of submillimetre galaxies (SMGs) and optically faint radio galaxies (OFRGs). In total, we detect 137 narrow-band emitter candidates down to emission-line fluxes of 0.5-1x10^-16^erg/s/cm^2^, across a total area of 0.56deg^2^ (2.1x10^5^ comoving Mpc^3^ at z=2.23) in these fields.
- ID:
- ivo://CDS.VizieR/J/ApJS/175/128
- Title:
- H{alpha} emitting galaxies in COSMOS-2 field
- Short Name:
- J/ApJS/175/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To derive a new H{alpha} luminosity function and to understand the clustering properties of star-forming galaxies at z~0.24, we have made a narrowband imaging survey for H{alpha}-emitting galaxies in the Hubble Space Telescope (HST) COSMOS 2 square degree field. We used the narrowband filter NB816 ({lambda}_c_=8150{AA}, {Delta}{lambda}=120{AA}) and sampled H{alpha} emitters with EW_obs_(H{alpha}+[NII])>12{AA} in a redshift range between z=0.233 and 0.251 corresponding to a depth of 70Mpc. We obtained 980 H{alpha}-emitting galaxies in a sky area of 5540arcmin^2^, corresponding to a survey volume of 3.1x10^4^Mpc^3^.
- ID:
- ivo://CDS.VizieR/J/A+A/613/L5
- Title:
- H{alpha} emitting sources around MWC758
- Short Name:
- J/A+A/613/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- MWC758 is a young star surrounded by a transitional disk. The disk shows an inner cavity and spiral arms that could be caused by the presence of protoplanets. Recently, a protoplanet candidate has been detected around MWC758 through high-resolution L'-band observations. The candidate is located inside the disk cavity at a separation of 111 mas from the central star, and at an average position angle of 165.5{deg}. We aim at detecting accreting protoplanet candidates within the disk of MWC758 through spectral angular differential imaging observations in the optical regime. In particular, we explore the emission at the position of the detected planet candidate. We have performed simultaneous adaptive optics observations in the H{alpha} line and the adjacent continuum using SPHERE/ZIMPOL at the Very Large Telescope (VLT). The data analysis does not reveal any H{alpha} signal around the target. The derived contrast curve in the B_Ha filter allows us to derive a 5{sigma} upper limit of 7.6mag at 111mas, the separation of the previously detected planet candidate. This contrast translates into a H{alpha} line luminosity of LH{alpha}<~5*10^-5^L_{sun}_ at 111mas. Assuming that LH{alpha} scales with Lacc as in Classical T Tauri stars as a first approximation, we can estimate an accretion luminosity of Lacc<3.7*10^-4^L_{sun}_ for the protoplanet candidate. For the predicted mass range of MWC758b, 0.5-5M_Jup_, this implies accretion rates smaller than dM/dt<3.4*(10^-8^-10^-9^)M_[sun}_/yr, for an average planet radius of 1.1 RJup. Therefore, our estimates are consistent with the predictions of accreting circumplanetary accretion models for R_in_=1R_Jup_. The ZIMPOL line luminosity is consistent with the H{alpha} upper limit predicted by these models for truncation radii <~3.2R_Jup_. The non-detection of any H{alpha}emitting source in the ZIMPOL images does not allow us to unveil the nature of the L' detected source. Either it is a protoplanet candidate or a disk asymmetry.
- ID:
- ivo://CDS.VizieR/J/ApJ/549/820
- Title:
- H{alpha} flux of ACCG 114 galaxies
- Short Name:
- J/ApJ/549/820
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a wide-field survey for H{alpha}-emitting galaxies in the cluster AC 114 at z=0.32. Spectra centered on H{alpha} at the cluster redshift have been obtained for 586 galaxies to I_tot_~22 out to a radius of ~h_50_^-1^Mpc. At most, only ~10% of these were found to be H{alpha}-emitting cluster members. These objects are predominantly blue and of late-type spiral morphology, consistent with them hosting star formation. However, ~65% of the cluster members classified morphologically as spirals (with HST) have no detectable H{alpha} emission; star formation and morphological evolution in cluster galaxies appear to be largely decoupled. Changes in the H{alpha} detection rate and the strength of H{alpha} emission with environment (as traced by local galaxy density) are found to be weak within the region studied. Star formation within the cluster members is also found to be strongly and uniformly suppressed with the rates inferred from the H{alpha} emission not exceeding 4M_{sun}_/yr, and AC 114's H{alpha} luminosity function being an order of magnitude below that observed for field galaxies at the same redshift. None of the galaxies detected have the high star formation rates associated with "starburst" galaxies; however, this may still be reconcilable with the known (8%+/-3%) fraction of "post-starburst" galaxies within AC 114, given the poorly determined but short lifetimes of starbursts and the possibility that much of the associated star formation is obscured by dust.
- 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.
