- ID:
- ivo://CDS.VizieR/J/AJ/157/22
- Title:
- Luminous and variable stars in NGC 2403 and M81
- Short Name:
- J/AJ/157/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of spectroscopy and multi-wavelength photometry of luminous and variable star candidates in the nearby spiral galaxies NGC 2403 and M81. We discuss specific classes of stars, the Luminous Blue Variables (LBVs), B[e] supergiants (sgB[e]), and the high-luminosity yellow hypergiants. We identify two new LBV candidates, and three sgB[e] stars in M81. We also find that some stars that were previously considered LBV candidates are actually field stars. The confirmed and candidate LBVs and sgB[e] stars together with the other confirmed members are shown on the HR Diagrams for their respective galaxies. We also present the HR Diagrams for the two "SN impostors", V37 (SN2002kg) and V12 (SN1954J) in NGC 2403 and the stars in their immediate environments.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/3138
- Title:
- Luminous cool supergiants in Magellanic Clouds
- Short Name:
- J/MNRAS/478/3138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The empirical upper luminosity boundary L_max_ of cool supergiants, often referred to as the Humphreys-Davidson limit, is thought to encode information on the general mass-loss behaviour of massive stars. Further, it delineates the boundary at which single stars will end their lives stripped of their hydrogen-rich envelope, which in turn is a key factor in the relative rates of Type-II to Type-Ibc supernovae from single star channels. In this paper we have revisited the issue of L_max_ by studying the luminosity distributions of cool supergiants (SGs) in the Large and Small Magellanic Clouds (LMC/SMC). We assemble highly-complete samples of cool SGs in each galaxy, and determine their spectral energy distributions from the optical to the mid-infrared using modern multi-wavelength survey data. We show that in both cases L_max_ appears to be lower than previously quoted, and is in the region of logL/L_{sun}_=5.5. There is no evidence for L_max_ being higher in the SMC than in the LMC, as would be expected if metallicity-dependent winds were the dominant factor in the stripping of stellar envelopes. We also show that L_max_ aligns with the lowest luminosity of single nitrogen-rich Wolf-Rayet stars, indicating of a change in evolutionary sequence for stars above a critical mass. From population synthesis analysis we show that the Geneva evolutionary models greatly over-predict the numbers of cool SGs in the SMC. We also argue that the trend of earlier average spectral types of cool SGs in lower metallicity environments represents a genuine shift to hotter temperatures. Finally, we use our new bolometric luminosity measurements to provide updated bolometric corrections for cool supergiants.
- ID:
- ivo://CDS.VizieR/J/MNRAS/386/1605
- Title:
- Luminous K-band selected QSOs from UKIDSS
- Short Name:
- J/MNRAS/386/1605
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The largest K-band flux-limited sample of luminous quasars to date has been constructed from the UKIRT (UK Infrared Telescope) Infrared Deep Sky Survey (UKIDSS) Large Area Survey Early Data Release, covering an effective area of 12.8deg^2^. Exploiting the K-band excess (KX) of all quasars with respect to foreground stars, including quasars experiencing dust reddening and objects with non-standard spectral energy distributions (SEDs), a list of targets suitable for spectroscopic follow-up observations with the AAOmega multi-object spectrograph is constructed, resulting in more than 200 confirmed active galactic nuclei (AGN). KX selection successfully identifies as quasar candidates objects that are excluded from the Sloan Digital Sky Survey (SDSS) quasar selection algorithm due to their colours being consistent with the stellar locus in optical colour space (with the space density of the excluded objects agreeing well with results from existing completeness analyses). Nearly half of the KX-selected quasars with K<=17.0 at z<3 are too faint in the i band to have been targeted by the SDSS quasar selection algorithm, revealing a large population of quasars with red i-K colours.
- ID:
- ivo://CDS.VizieR/J/ApJ/829/33
- Title:
- Luminous of high-z QSOs with SDSS and WISE. II
- Short Name:
- J/ApJ/829/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper in a series on a new luminous z~5 quasar survey using optical and near-infrared colors. Here we present a new determination of the bright end of the quasar luminosity function (QLF) at z~5. Combining our 45 new quasars with previously known quasars that satisfy our selections, we construct the largest uniform luminous z~5 quasar sample to date, with 99 quasars in the range of 4.7<=z<5.4 and -29<M_1450_<=-26.8, within the Sloan Digital Sky Survey (SDSS) footprint. We use a modified 1/V_a_ method including flux limit correction to derive a binned QLF, and we model the parametric QLF using maximum likelihood estimation. With the faint-end slope of the QLF fixed as {alpha}=-2.03 from previous deeper samples, the best fit of our QLF gives a flatter bright end slope {beta}=-3.58+/-0.24 and a fainter break magnitude M_1450_^*^=-26.98+/-0.23 than previous studies at similar redshift. Combined with previous work at lower and higher redshifts, our result is consistent with a luminosity evolution and density evolution model. Using the best-fit QLF, the contribution of quasars to the ionizing background at z~5 is found to be 18%-45% with a clumping factor C of 2-5. Our sample suggests an evolution of radio loud fraction with optical luminosity but no obvious evolution with redshift.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/117
- Title:
- Luminous (sub-)millimetre galaxies
- Short Name:
- J/MNRAS/444/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Motivated by the current controversy over the redshift distribution and physical properties of luminous (sub-)mm sources, we have undertaken a new study of the brightest sample of unlensed (sub-)mm sources with pre-Atacama Large Millimeter/submillimeter Array (ALMA) interferometric follow-up in the Cosmological Evolution Survey field. Exploiting the very latest multifrequency supporting data, we find that this sample displays a redshift distribution indistinguishable from that of the lensed sources uncovered with the South Pole Telescope, with z_median_=~3.5. We also find that, over the redshift range z=~2-6, the median stellar mass of the most luminous (sub-) mm sources is M_*_=~ 3x10^11^M_{sun}_, yielding a typical specific star formation rate sSFR=~3Gyr^-1^. Consistent with recent ALMA and the Submillimeter Array studies, we confirm that source blending is not a serious issue in the study of luminous (sub-)mm sources uncovered by ground-based, single-dish surveys; only =~10^-15^% of bright (S_850_=~5-10mJy) (sub-) mm sources arise from significant (i.e. >20%) blends, and so our conclusions are largely unaffected by whether we adopt the original single-dish mm/sub-mm flux densities/positions or the interferometric data. Our results suggest that apparent disagreements over the redshift distribution of (sub-)mm sources are a result of 'down-sizing' in dust-enshrouded star formation, consistent with existing knowledge of the star formation histories of massive galaxies. They also indicate that extreme star-forming galaxies at high redshift are, on average, subject to the same star formation rate-limiting processes as less luminous objects, and lie on the 'main sequence' of star-forming galaxies at z>3.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/64
- Title:
- Luminous variable stars in M31 & M33. IV.
- Short Name:
- J/ApJ/836/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this series of papers we have presented the results of a spectroscopic survey of luminous stars in the nearby spirals M31 and M33. Here, we present spectroscopy of 132 additional stars. Most have emission-line spectra, including luminous blue variables (LBVs) and candidate LBVs, Fe II emission line stars, the B[e] supergiants, and the warm hypergiants. Many of these objects are spectroscopically similar and are often confused with each other. We examine their similarities and differences and propose the following guidelines that can be used to help distinguish these stars in future work. (1) The B[e] supergiants have emission lines of [OI] and [FeII] in their spectra. Most of the spectroscopically confirmed sgB[e] stars also have warm circumstellar dust in their spectral energy distributions (SEDs). (2) Confirmed LBVs do not have the [OI] emission lines in their spectra. Some LBVs have [FeII] emission lines, but not all. Their SEDs show free-free emission in the near-infrared but no evidence for warm dust. Their most important and defining characteristic is the S Dor-type variability. (3) The warm hypergiants spectroscopically resemble the LBVs in their dense wind state and the B[e] supergiants. However, they are very dusty. Some have [FeII] and [OI] emission in their spectra like the sgB[e] stars, but are distinguished by their A- and F-type absorption-line spectra. In contrast, the B[e] supergiant spectra have strong continua and few if any apparent absorption lines. Candidate LBVs should share the spectral characteristics of the confirmed LBVs with low outflow velocities and the lack of warm circumstellar dust.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/37
- Title:
- Luminous WISE-selected quasars in SDSS Stripe 82
- Short Name:
- J/ApJ/861/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopically complete sample of 147 infrared-color-selected active galactic nuclei (AGNs) down to a 22{mu}m flux limit of 20mJy over the ~270deg^2^ of the Sloan Digital Sky Survey Stripe 82 region. Most of these sources are in the QSO luminosity regime (Lbol>~10^12^L_{sun}_) and are found out to z~3. We classify the AGNs into three types, finding 57 blue, unobscured Type-1 (broad-lined) sources; 69 obscured, Type-2 (narrow-lined) sources; and 21 moderately reddened Type-1 sources (broad-lined and E(B-V)>0.25). We study a subset of this sample in X-rays and analyze their obscuration to find that our spectroscopic classifications are in broad agreement with low, moderate, and large amounts of absorption for Type-1, red Type-1, and Type-2 AGNs, respectively. We also investigate how their X-ray luminosities correlate with other known bolometric luminosity indicators such as [OIII] line luminosity (L[OIII]) and infrared luminosity (L6{mu}m). While the X-ray correlation with L[OIII] is consistent with previous findings, the most infrared-luminous sources appear to deviate from established relations such that they are either underluminous in X-rays or overluminous in the infrared. Finally, we examine the luminosity function evolution of our sample, and by AGN type, in combination with the complementary, infrared-selected, AGN sample of Lacy et al. (2013), spanning over two orders of magnitude in luminosity. We find that the two obscured populations evolve differently, with reddened Type-1 AGNs dominating the obscured AGN fraction (~30%) for L_5{mu}m_>10^45^erg/s, while the fraction of Type-2 AGNs with L_5{mu}m_<10^45^erg/s rises sharply from 40% to 80% of the overall AGN population.
- ID:
- ivo://CDS.VizieR/J/AJ/112/2786
- Title:
- 1985-1995 lunar occultations at TIRGO
- Short Name:
- J/AJ/112/2786
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A program of observations of lunar occultations in the near-infrared was started at the TIRGO observatory in late 1985. After ten years of operation, we provide a list of all the events recorded up to the end of 1995 using the facility IR photometer. A total of 157 light curves were obtained, mostly aiming at measurements of angular diameters and binaries, with a total of 54 results in these fields. In Table 1 is reported a summary of the occultation events and the parameters of their observations. In Table 2 is reported a list of cross-identifications, coordinates, and characteristics.
- ID:
- ivo://CDS.VizieR/J/A+A/529/A108
- Title:
- Lupus clouds proper motion study with VO
- Short Name:
- J/A+A/529/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Lupus dark cloud complex is a well-known, nearby low-mass star-forming region, probably associated with the Gould Belt. In recent years, the number of stellar and substellar Lupus candidate members has been remarkably increased thanks to the Cores to Disks (c2d) Spitzer Legacy Program and other studies. However, most of these newly discovered objects still lack confirmation that they belong to the dark clouds. By using available kinematical information, we test the membership of the new Lupus candidate members proposed by the c2d program and by a complementary optical survey. We also investigate the relationship between the proper motions and other properties of the objects, in order to get some clues about their formation and early evolution. We compiled a list of members and possible members of Lupus 1, 3, and 4, together with all available information on their spectral types, disks, and physical parameters. Using Virtual Observatory tools, we cross-matched this list with the available astrometric catalogues to get proper motions for our objects. Our final sample contains sources with magnitudes I<16mag and estimated masses >~0.1M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+A/521/A19
- Title:
- 21 Lutetia UBVRI light curves
- Short Name:
- J/A+A/521/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroid 21 Lutetia is the second target of the Rosetta space mission. Extensive pre-encounter, space-, and ground-based observations are being performed to prepare for the flyby in July 2010. The aim of this article is to accurately characterize the photometric properties of this asteroid over a broad spectral range from the ultraviolet to the near-infrared and to search for evidence of surface inhomogeneities.
