- ID:
- ivo://CDS.VizieR/J/MNRAS/365/401
- Title:
- New planetary nebulae in LMC
- Short Name:
- J/MNRAS/365/401
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report our initial discovery of 73 new planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) following confirmatory 2dF spectroscopy on the Anglo-Australian Telescope. Preliminary candidate sources come from a 10 per cent sub-area of our new deep, high-resolution H{alpha} map of the central 25deg^2^ of the LMC obtained with the UK Schmidt Telescope. The depth of the high-resolution map was extended to R_equiv_~22 for H{alpha} (4.5x10^-17^erg/cm^2^/s/{AA}) by a process of multi-exposure median co-addition of a dozen 2-h H{alpha} exposures. The resulting map is at least 1-mag deeper than the best wide-field narrow-band LMC images currently available. This depth, combined with our selection technique, has also led to the discovery of extended asymptotic giant branch (AGB) haloes around many new and previously known LMC PNe for the first time. Once complete, our new survey is expected to triple the LMC PN population and have significant implications for the LMC PN luminosity function, kinematics, abundance gradients, chemical evolution and, via study of the AGB haloes, the initial to final mass relation for low- to intermediate-mass stars.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/659/A45
- Title:
- NGC4330 GHASP and PUMA datacubes
- Short Name:
- J/A+A/659/A45
- Date:
- 04 Mar 2022 00:48:25
- Publisher:
- CDS
- Description:
- Using the VESTIGE survey, a deep narrow-band H{alpha} imaging survey of the Virgo cluster carried on at the CFHT with MegaCam, we have discovered a long and diffuse tail of ionised gas in the edge-on late-type galaxy NGC4330. This peculiar feature witnesses an ongoing ram pressure stripping event able to remove the gas in the outer region of the disc. Tuned hydrodynamic simulations suggest that the ram pressure stripping event is occurring almost face-on, making NGC4330 the ideal candidate to study the effects of the perturbation in the direction perpendicular to the disc plane. We present here two new independent sets of Fabry-Perot observations (R~10000) with the purpose of understanding the effects of ram pressure stripping process on the kinematics of the ionised gas. Despite their limited sensitivity to the diffuse gas emission, the data allowed us to measure the velocity and the velocity dispersion fields over the galaxy disc and in several features at the edges or outside the stellar disc formed after the ram pressure stripping event. We have constructed the position-velocity diagrams and the rotation curves of the galaxy using three different techniques. The data show, consistent with the hydrodynamic simulations, that the galaxy has an inner solid-body rotation up to ~2.4kpc, with noncircular streaming motions outwards the disc and in the several external features formed during the interaction of the galaxy with the surrounding intracluster medium. The data also indicate a decrease of the rotational velocity of the gas with increasing distance from the galaxy disc along the tails, suggesting a gradual but not linear loss of angular momentum in the stripped gas. Consistent with a ram pressure stripping scenario, the i-band image shows a boxy shape at the southwest edge of the disc, where the stellar orbits might have been perturbed by the modification of the gravitational potential well of the galaxy due to the displacement of the gas in the z-direction.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A8
- Title:
- NGC3447/NGC3447A maps
- Short Name:
- J/A+A/610/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Local Group (LG) Analogs (LGAs) are galaxy associations dominated by a few bright spirals reminiscent of the LG. The NGC3447/NGC3447A system is a member of the LGG 225 group, a nearby LGA. This system is considered a physical pair composed of an intermediate-luminosity late-type spiral, NGC3447 itself, and an irregular companion, NGC3447A, linked by a faint, short filament of matter. A ring-like structure in the NGC3447 outskirts has been emphasised by Galaxy Evolution Explorer (GALEX) observations. This work aims to contribute to the study of galaxy evolution in low-density environments, a favourable habitat to highly effective encounters, shedding light on the evolution of the NGC3447/NGC3447A system. We performed a multi-{lambda} analysis of the surface photometry of this system to derive its spectral energy distribution and structural properties using ultraviolet (UV), Swift UVOT, and optical Sloan Digital Sky Survey (SDSS) images complemented with available far-IR observations. We also characterised the velocity field of the pair using two-dimensional H{alpha} kinematical observations of the system obtained with PUMA Fabry-Perot interferometer at the 2.1m telescope of San Pedro Martir (Mexico). All these data are used to constrain smooth particle hydrodynamic simulations with chemo-photometric implementation to shed light on the evolution of this system. The luminosity profiles, from UV to optical wavelengths, are all consistent with the presence of a disc extending and including NGC3447A. The overall velocity field does not emphasise any significant rotation pattern, rather a small velocity gradient between NGC3447 and NGC3447A. Our simulation, detached from a large grid explored to best-fit the global properties of the system, suggests that this arises from an encounter between two halos of equal mass.
- ID:
- ivo://CDS.VizieR/J/MNRAS/484/5102
- Title:
- NGC 6383 T Tauri accretion rates
- Short Name:
- J/MNRAS/484/5102
- Date:
- 03 Nov 2021 13:02:39
- Publisher:
- CDS
- Description:
- This paper presents optical (ugriH{alpha})-infrared (JHKs, 3.6-8.0um) photometry and Gaia astrometry of 55 Classical T-Tauri stars (CTTS) in the star-forming region Sh 2-012 and its central cluster NGC 6383. The sample was identified based on photometric H{alpha} emission linewidths, and has a median age of 2.8+/-1.6Myr, with a mass range between 0.3 and 1M_{sun}_. 94 per cent of CTTS with near-infrared cross-matches fall on the near-infrared T-Tauri locus, with all stars having mid-infrared photometry exhibiting evidence for accreting circumstellar discs. CTTS are found concentrated around the central cluster NGC 6383, and towards the bright rims located at the edges of Sh 2-012. Stars across the region have similar ages, suggestive of a single burst of star formation. Mass accretion rates dMacc/dt) estimated via H{alpha} and u-band line intensities show a scatter (0.3dex) similar to spectroscopic studies, indicating the suitability of H{alpha} photometry to estimate dMacc/dt. Examining the variation of dMacc/dt with stellar mass (M*), we find a smaller intercept in the (dMacc/dt)-M* relation than oft-quoted in the literature, providing evidence to discriminate between competing theories of protoplanetary disc evolution.
- ID:
- ivo://CDS.VizieR/J/AJ/115/734
- Title:
- NGC 6231 UBVRI and H{alpha} photometry
- Short Name:
- J/AJ/115/734
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI and H{alpha} CCD photometry has been obtained for the young open cluster NGC 6231. From the R-H{alpha} color, a measure of the H{alpha} emission, we find 12 pre-main-sequence (PMS) members and seven possible PMS members in the cluster. Applying recent stellar evolutionary tracks and PMS evolutionary tracks, we derive the age, age spread, and initial mass function of the cluster. The initial mass function of NGC 6231 is a Gaussian with a turnover at logm~0.4 (m~2.5M_{Sun}_) and shows an abrupt decrease in the number of low-mass stars. Possible reasons for the suppression of low-mass star formation and star formation processes are discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A99
- Title:
- NGVS 3543 images at 8 wavelengths
- Short Name:
- J/A+A/650/A99
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The interaction of galaxies with their environment plays an important role in their evolution. Ultra-diffuse galaxies (UDGs) have been found in large numbers in clusters. We detected a few star forming blobs in the VESTIGE survey, located at ~5kpc from a UDG, namely NGVS 3543, in association with an HI gas cloud AGC 226178, suggesting a recent interaction of this low surface brightness system with the surrounding cluster environment. We use a complete set of multi-frequency data including deep optical, UV, and narrow- band H{alpha} imaging and HI data to understand the formation process which gave birth to this peculiar system. For this purpose, we measured: i) multi-wavelength radial surface brightness profiles of NGVS 3543 and compared them to the predictions of spectro-photometric models of galaxy evolution in rich clusters, ii) aperture photometry of the blue regions in the vicinity of NGVS 3543 in order to determine their age and stellar mass. The comparison of the observations with the evolutionary models indicate that the NGVS 3543 has undergone a ram-pressure stripping (RPS) that peaked ~100Myr ago, transforming a blue gas-rich UDG into a red gas-poor UDG. Star formation has taken place in the ram pressure stripped gas, whose mass is ~10^8^M_{sun}_, forming star complexes of typical age ~20Myr and stellar mass ~10^4^M_{sun}_. These results suggest that we are observing for the first time the ongoing transformation of a gas-rich UDG into a red and quiescent UDG under the effect of a ram-pressure stripping event. The same process could thus explain the lack of star forming UDGs in rich environments observed in several nearby clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/159/153
- Title:
- Optical and IR photometry in the HII region Sh2-242
- Short Name:
- J/AJ/159/153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here identification and characterization of the young stellar population associated with an active star-forming site Sh2-242. We used our own new optical imaging and spectroscopic observational data, as well as several archival catalogs, e.g., Pan-STARRS-1, Gaia-DR2, Isaac Newton Telescope Photometric H-Alpha Survey (IPHAS), Wide-field InfraRed Camera, 2MASS, and Spitzer. Slit spectroscopic results confirm the classification of the main ionizing source BD+26980 as an early-type star of spectral type B0.5V. The spectrophotometric distance of the star is estimated as 2.08{+/-}0.24kpc, which confirms the source as a member of the cluster. An extinction map covering a large area (diameter ~50') is generated with H and K photometry toward the region. From the map, three distinct locations of peak extinction complexes (A_V_~7-17mag) are identified for the very first time. Using the infrared color excess, a total of 33 Class I and 137 Class II young objects are classified within the region. The IPHAS photometry reveals classification of 36 H{alpha} emitting sources, which might be class II objects. Among 36 H{alpha} emitting sources, 5 are already identified using infrared excess emission. In total, 201 young objects are classified toward S242 from this study. The membership status of the young sources is further windowed with the inclusion of parallax from the Gaia DR2 catalog. Using the optical and infrared color-magnitude diagrams, the young stellar objects are characterized with an average age of ~1Myr and masses in the range 0.1-3.0M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJS/183/261
- Title:
- Optical photometry of the ONC
- Short Name:
- J/ApJS/183/261
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present U, B, V, I broadband, 6200{AA} TiO medium band, and H{alpha} narrow band photometry of the Orion Nebula Cluster (ONC) obtained with the WFI imager at the ESO/MPI 2.2 telescope at La Silla Observatory. The nearly simultaneous observations cover the entire ONC in a field of about 34x34arcmin^2^. They enable us to determine stellar colors avoiding the additional scatter in the photometry induced by stellar variability typical of pre-main-sequence stars. We identify 2612 point-like sources in the I band; 58%, 43%, and 17% of them are also detected in V, B, and U, respectively. 1040 sources are identified in the H{alpha} band. In this paper we present the observations, the calibration techniques adopted, and the resulting catalog. We show the derived color-magnitude diagram of the population and discuss the completeness of our photometry. We define a spectrophotometric TiO index that takes into account the fluxes in the V, I, and TiO bands. Comparing it with spectral types of ONC members in the literature, we find a correlation between the index and the spectral type valid for M-type stars, which is accurate to better than 1 spectral subclass for M3-M6 types and better than 2 spectral subclasses for M0-M2 types. This allows us to newly classify 217 stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/875/85
- Title:
- Optical search for SNRs in NGC6946 with WIYN & GMOS
- Short Name:
- J/ApJ/875/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relatively nearby spiral galaxy NGC 6946 is one of the most actively star-forming galaxies in the local universe. Ten supernovae (SNe) have been observed since 1917, and hence NGC 6946 surely contains a large number of supernova remnants (SNRs). Here we report a new optical search for these SNRs using narrowband images obtained with the WIYN telescope. We identify 147 emission nebulae as likely SNRs, based on elevated [SII]:H{alpha} ratios compared to HII regions. We have obtained spectra of 102 of these nebulae with Gemini North-GMOS; of these, 89 have [SII]:H{alpha} ratios greater than 0.4, the canonical optical criterion for identifying SNRs. There is very little overlap between our sample and the SNR candidates identified by Lacey+ (1997ApJS..109..417L) from radio data. Also, very few of our SNR candidates are known X-ray sources, unlike the situation in some other galaxies such as M33 and M83. The emission-line ratios, e.g., [NII]:H{alpha}, of the candidates in NGC 6946 are typical of those observed in SNR samples from other galaxies with comparable metallicity. None of the candidates observed in our low-resolution spectra show evidence of anomalous abundances or significant velocity broadening. A search for emission at the sites of all the historical SNe in NGC 6946 resulted in detections for only two: SN 1980K and SN 2004et. Spectra of both show very broad, asymmetric line profiles, consistent with the interaction between SN ejecta and the progenitor star's circumstellar material, as seen in late spectra from other core-collapse SNe of similar age.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/3
- Title:
- Optical & Spitzer photometry in IC 1805
- Short Name:
- J/ApJS/230/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep wide-field optical CCD photometry and mid-infrared Spitzer/IRAC and MIPS 24{mu}m data for about 100000 stars in the young open cluster IC 1805. The members of IC 1805 were selected from their location in the various color-color and color-magnitude diagrams, and the presence of H{alpha} emission, mid-infrared excess emission, and X-ray emission. The reddening law toward IC 1805 is nearly normal (R_V_=3.05+/-0.06). However, the distance modulus of the cluster is estimated to be 11.9+/-0.2mag (d=2.4+/-0.2kpc) from the reddening-free color-magnitude diagrams, which is larger than the distance to the nearby massive star-forming region W3(OH) measured from the radio VLBA astrometry. We also determined the age of IC 1805 ({tau}_MSTO_=3.5Myr). In addition, we critically compared the age and mass scale from two pre-main-sequence evolution models. The initial mass function with a Salpeter-type slope of {Gamma}=-1.3+/-0.2 was obtained and the total mass of IC 1805 was estimated to be about 2700+/-200M_{sun}_. Finally, we found our distance determination to be statistically consistent with the Tycho-Gaia Astrometric Solution Data Release 1, within the errors. The proper motion of the B-type stars shows an elongated distribution along the Galactic plane, which could be explained by some of the B-type stars being formed in small clouds dispersed by previous episodes of star formation or supernova explosions.
