- ID:
- ivo://CDS.VizieR/J/A+A/658/A4
- Title:
- LOFAR imaging of Arp299 at 150MHz
- Short Name:
- J/A+A/658/A4
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the spatially resolved emission of Arp 299 revealed by 150 MHz international baseline Low-Frequency Array (LOFAR) and 1.4, 5.0, and 8.4GHz Very Large Array (VLA) observations. Nowadays, LOFAR allows to compare its resolution with the VLA ones. These will allow us to obtain pixel-by-pixel spectral imdex maps and local radio SEDs. With this information we recover the nature of the ISM around the main structures (either clumpy or continuous), as well as magnetic fields. The 150MHz image also shows structures never seen before, pointing out that these radio-frequencies observations are a perfect tool to detect them.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/823/157
- Title:
- LOS velocities & [Fe/H] of Pal 5 tidal stream
- Short Name:
- J/ApJ/823/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Subaru/Faint Object Camera and Spectrograph and Keck/Deep Imaging Multi-Object Spectrometer medium-resolution spectroscopy of a tidally disrupting Milky Way (MW) globular cluster Palomar 5 (Pal 5) and its tidal stream. The observed fields are located to cover an angular extent of ~17{deg} along the stream, providing an opportunity to investigate a trend in line-of-sight velocities (V_los_) along the stream, which is essential to constrain its orbit and underlying gravitational potential of the MW's dark matter halo. A spectral fitting technique is applied to the observed spectra to obtain stellar parameters and metallicities ([Fe/H]) of the target stars. The 19 stars most likely belonging to the central Pal 5 cluster have a mean V_los_ of -58.1+/-0.7km/s and metallicity [Fe/H]=-1.35+/-0.06dex, both of which are in good agreement with those derived in previous high-resolution spectroscopic studies. Assuming that the stream stars have the same [Fe/H] as the progenitor cluster, the derived [Fe/H] and V_los_ values are used to estimate the possible V_los_ range of the member stars at each location along the stream. Because of the heavy contamination of the field MW stars, the estimated V_los_ range depends on prior assumptions about the stream's V_los_, which highlights the importance of more definitely identifying the member stars using proper motion and chemical abundances to obtain unbiased information of V_los_ in the outer part of the Pal 5 stream. The models for the gravitational potential of the MW's dark matter halo that are compatible with the estimated V_los_ range are discussed.
- ID:
- ivo://CDS.VizieR/J/ApJS/179/249
- Title:
- Low-luminosity embedded protostar population
- Short Name:
- J/ApJS/179/249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for all embedded protostars with internal luminosities <=1.0L_{sun}_ in the full sample of nearby, low-mass star-forming regions surveyed by the Spitzer Space Telescope Legacy Project "From Molecular Cores to Planet Forming Disks" (c2d). We present a set of selection criteria used to identify candidates from the Spitzer data and examine complementary data to decide whether each candidate is truly an embedded protostar. Between 75% and 85% of cores classified as starless prior to being observed by Spitzer remain starless to our luminosity sensitivity; the remaining 15%-25% harbor low-luminosity, embedded protostars. We compile complete spectral energy distributions for all 50 objects and calculate standard evolutionary signatures (L_bol_, T_bol_, and L_bol_/L_smm_) and argue that these objects are inconsistent with the simplest picture of star formation, wherein mass accretes from the core onto the protostar at a constant rate.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A138
- Title:
- Low-luminosity type-1 QSO sample. V.
- Short Name:
- J/A+A/587/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared (NIR) H+K-band long-slit spectra of eleven galaxies that were obtained with SOFI at the NTT (ESO). The galaxies are chosen from the low-luminosity type-1 quasi-stellar object (LLQSO) sample, which comprises the 99 closest (z<=0.06) QSOs from the Hamburg/ESO survey for bright UV-excess QSOs. These objects are ideal targets to study the gap between local Seyfert galaxies and high-redshift quasars because they show much stronger AGN activity than local objects, but are still close enough for a detailed structural analysis. We fit hydrogen recombination, molecular hydrogen, and [FeII] lines after carefully subtracting the continuum emission. From the broad Pa{alpha} components, we estimated black hole masses and enlarged the sample of LLQSOs that deviate from the MBH-Lbulge relations of inactive galaxies from 12 to 16 objects. All objects show emission from hot dust (T~1200K) as well as stellar contribution. However, the respective fractions vary strongly among the objects. More than half of the objects show H_2_ emission lines, which indicate a large reservoir of molecular gas that is needed to feed the AGN and star formation. In the NIR diagnostic diagram all objects lie in the location of AGN-dominated objects. However, most of the objects show indications of star formation activity, suggesting that their offset location with respect to MBH-Lbulge relations of inactive galaxies may be a consequence of overluminous bulges.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A111
- Title:
- Low-mass stars in Coma Ber
- Short Name:
- J/A+A/544/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Little is known about the population of the Coma Berenices open cluster (age~500Myr) below 0.2M_{sun}_, and statistics show that there is a prominent deficit of very low-mass objects in this mass range compared to younger open clusters with ages of <250Myr. We search for very low-mass stars and substellar objects (brown dwarfs) in the Coma open cluster to derive the present-day cluster mass function below 0.2M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/153/84
- Title:
- Low-resolution near-infrared stellar spectra from CIBER
- Short Name:
- J/AJ/153/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared (0.8-1.8{mu}m) spectra of 105 bright (m_J_<10) stars observed with the low-resolution spectrometer on the rocket-borne Cosmic Infrared Background Experiment. As our observations are performed above the Earth's atmosphere, our spectra are free from telluric contamination, which makes them a unique resource for near-infrared spectral calibration. Two-Micron All-Sky Survey photometry information is used to identify cross-matched stars after reduction and extraction of the spectra. We identify the spectral types of the observed stars by comparing them with spectral templates from the Infrared Telescope Facility library. All the observed spectra are consistent with late F to M stellar spectral types, and we identify various infrared absorption lines.
- ID:
- ivo://CDS.VizieR/J/PASJ/65/119
- Title:
- Low-resolution NIR spectra of zodiacal light
- Short Name:
- J/PASJ/65/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains the 278 low-resolution (R~20) near-infrared (1.8-5.3micron) spectra of diffuse sky covering a wide range of galactic and ecliptic latitudes with the Infrared Camera (IRC) on board AKARI before the exhaustion of liquid-helium (from September 2006 to May 2007). Advanced reduction methods specialized for the slit spectroscopy of diffuse sky spectra are developed for constructing this spectral catalog. Filter wheel of the IRC instrument has dark position to measure the dark current, and uncertainty due to dark current subtraction is estimated to be <3nW/m2/sr at 2micron (Tsumura & Wada, 2011PASJ...63..755T). Point sources brighter than mK(Vega)=19 were detected on the slit and masked for deriving the diffuse spectrum. It was confirmed that the brightness due to unresolved galactic stars under this detection limit is negligible (<0.5% of the sky brightness at 2.2 micron) by a Milky Way star count model (TRILEGAL; Girardi et al., 2005A&A...436..895G). Cumulative brightness contributed by unresolved galaxies can be estimated by the deep galaxy counts, being <4nW/m2/sr at K band in the case of limiting magnitude of mK=19 (Keenan et al., 2010ApJ...723...40K).
- ID:
- ivo://CDS.VizieR/J/AJ/145/94
- Title:
- Luminosities of protostars from two Spitzer surveys
- Short Name:
- J/AJ/145/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Motivated by the long-standing "luminosity problem" in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate L_bol_ for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01L_{sun}_ to 69L_{sun}_, and has a mean and median of 4.3L_{sun}_ and 1.3L_{sun}_, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (L_bol_<~0.5L_{sun}_) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70{mu}m<{lambda}<850{mu}m) and have L_bol_ underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source individually once additional data becomes available will likely increase both the mean and median of the sample by 35%-40%. We discuss and compare our results to several recent theoretical studies of protostellar luminosities and show that our new results do not invalidate the conclusions of any of these studies. As these studies demonstrate that there is more than one plausible accretion scenario that can match observations, future attention is clearly needed. The better statistics provided by our increased data set should aid such future work.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A130
- Title:
- Luminous infrared galaxies AKARI 2.5-5um data
- Short Name:
- J/A+A/617/A130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present AKARI 2.5-5um spectra of 145 local luminous infrared galaxies (LIRG; L_IR_>=10^11^L_{sun}_) in the Great Observatories All-sky LIRG Survey (GOALS). In all of the spectra, we measure the line fluxes and equivalent widths (EQWs) of the polycyclic aromatic hydrocarbon (PAH) at 3.3um and the hydrogen recombination line Br{alpha} at 4.05um, with apertures matched to the slit sizes of the Spitzer low-resolution spectrograph and with an aperture covering ~95% of the total flux in the AKARI two-dimensional (2D) spectra. The star formation rates (SFRs) derived from the Br{alpha} emission measured in the latter aperture agree well with SFRs estimated from LIR, when the dust extinction correction is adopted based on the 9.7um silicate absorption feature. Together with the Spitzer Infrared Spectrograph (IRS) 5.2-38um spectra, we are able to compare the emission of the PAH features detected at 3.3um and 6.2um. These are the two most commonly used near/mid-infrared indicators of starburst or active galactic nucleus (AGN) dominated galaxies. We find that the 3.3um and 6.2um PAH EQWs do not follow a linear correlation and at least a third of the galaxies classified as AGN-dominated sources using the 3.3um feature are classified as starbursts based on the 6.2um feature. These galaxies have a bluer continuum slope than galaxies that are indicated to be starburst-dominated by both PAH features. The bluer continuum emission suggests that their continuum is dominated by stellar emission rather than hot dust. We also find that the median Spitzer/IRS spectra of these sources are remarkably similar to the pure starburst-dominated sources indicated by high PAH EQWs in both 3.3um and 6.2um. Based on these results, we propose a revised starburst/AGN diagnostic diagram using 2-5um data: the 3.3um PAH EQW and the continuum color, F{nu}(4.3um)/F{nu}(2.8um). We use the AKARI and Spitzer spectra to examine the performance of our new starburst/AGN diagnostics and to estimate 3.3um PAH fluxes using the James Webb Space Telescope (JWST) photometric bands in the redshift range 0<z<5. Of the known PAH features and mid-infrared high ionization emission lines used as starburst/AGN indicators, only the 3.3um PAH feature is observable with JWST at z>3.5, because the rest of the features at longer wavelengths fall outside the JWST wavelength coverage.
- ID:
- ivo://CDS.VizieR/J/ApJS/154/155
- Title:
- Luminous X-ray sources Chandra fluxes
- Short Name:
- J/ApJS/154/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the luminous X-ray sources in the Lockman Hole (LH) and the extended Groth strip (EGS) detected at 24{mu}m using the Multiband Imaging Photometer (MIPS) and also with the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope. We assemble optical/infrared spectral energy distributions (SEDs) for 45 X-ray/24{mu}m sources in the EGS and LH. Only about one-quarter of the hard X-ray/24{mu}m sources show pure type 1 active galactic nucleus (AGN) SEDs. More than half of the X-ray/24{mu}m sources have stellar emission-dominated or obscured SEDs, similar to those of local type 2 AGN and spiral/starburst galaxies. One-third of the sources detected in hard X-rays do not have a 24{mu}m counterpart. Two such sources in the LH have SEDs resembling those of S0/elliptical galaxies. The broad variety of SEDs in the optical-to-Spitzer bands of X-ray-selected AGNs means that AGNs selected according to the behavior in the optical/infrared will have to be supplemented by other kinds of data (e.g., X-ray) to produce unbiased samples of AGNs.
