- ID:
- ivo://nasa.heasarc/rotxraycat
- Title:
- StarswithRotationPeriods&X-RayLuminositiesCatalog
- Short Name:
- ROTXRAYCAT
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains photometric and derived stellar parameters for a sample of 820 solar and late-type stars (the original table of 824 entries had 4 near-duplicate entries for the stars HD 19668, HD 95188, HD 216803 and HD 285382 which have been removed by the HEASARC) from nearby open clusters and the field, including rotation periods and X-ray luminosities. This sample was used by the authors to study the relationship between rotation and stellar activity and derive a new estimate of the convective turnover time. From an unbiased subset of this sample the power law slope of the unsaturated regime, L<sub>X</sub>/L<sub>bol</sub> ~ R<sub>o</sub><sup>beta</sup>, is fit as beta = -2.70 +/- 0.13. This is inconsistent with the canonical beta = -2 slope to a confidence of 5 sigma, and argues for an additional term in the dynamo number equation. From a simple scaling analysis, this implies Delta(Omega)/Omega ~ Omega<sup>0.7</sup>, i.e. the differential rotation of solar-type stars gradually declines as they spin down. Super-saturation is observed for the fastest rotators in this sample and its parametric dependencies are explored. Significant correlations are found with both the corotation radius and the excess polar updraft, the latter theory providing a stronger dependence and being supported by other observations. The authors estimate mass-dependent empirical thresholds for saturation and super- saturation and map out three regimes of coronal emission. Late F-type stars are shown never to pass through the saturated regime, passing straight from super-saturated to unsaturated X-ray emission. The theoretical threshold for coronal stripping is shown to be significantly different from the empirical saturation threshold (R<sub>o</sub> < 0.13), suggesting it is not responsible. Instead, the authors suggest that a different dynamo configuration is at work in stars with saturated coronal emission. This is supported by a correlation between the empirical saturation threshold and the time when stars transition between convective and interface sequences in rotational spin-down models. This table was created by the HEASARC in March 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/743/48">CDS Catalog J/ApJ/743/48</a> file catalog.dat. The original table had 824 entries, including 4 near-duplicate entries for the stars HD 19668, HD 95188, HD 216803 and HD 285382, which have been removed by the HEASARC. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/vlagbsoph
- Title:
- VLA Goulds Belt Survey Ophiuchus Complex Source Catalog
- Short Name:
- VLAGBSOPH
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from large-scale (~2000 arcmin<sup>2</sup>), deep (~20 µJy), high-resolution (~1") radio observations of the Ophiuchus star-forming complex obtained with the Karl G. Jansky Very Large Array (JVLA) at wavelengths of 4 and 6 cm (frequencies of 7.5 and 4.5 GHz). In total, 189 sources were detected, 56 of them associated with known young stellar objects (YSOs), and 4 with known extragalactic objects; the other 129 remain unclassified, but most of them are most probably background quasars. The vast majority of the young stars detected at radio wavelengths have spectral types K or M, although four objects of A/F/B types and two brown dwarf candidates are also detected. At least half of these young stars are non-thermal (gyrosynchrotron) sources, with active coronae characterized by high levels of variability, negative spectral indices, and (in some cases) significant circular polarization. As expected, there is a clear tendency for the fraction of non-thermal sources to increase from the younger (Class 0/I or flat spectrum) to the more evolved (Class III or weak-line T Tauri) stars. The young stars detected both in X-rays and at radio wavelengths broadly follow a Gudel-Benz relation, but with a different normalization than the most radio-active types of stars. Finally, the authors detected a ~70 mJy compact extragalactic source near the center of the Ophiuchus core, which should be used as gain calibrator for any future radio observations of this region. The observations were obtained with the JVLA of the National Radio Astronomy Observatory (NRAO). Two frequency sub-bands, each 1-GHz wide, and centered at 4.5 and 7.5 GHz, respectively, were recorded simultaneously. The observations were obtained on three different epochs (2011 February 17/19, April 3/4, and May 4/6) typically separated from one another by a month. The angular resolution of the observations is of the order of 1 arcsecond. To identify sources in their observations, the authors used the images corresponding to the concatenation of the three epochs, which provided the highest sensitivity. The criteria used to consider a detection as firm were: (1) sources with reported counterparts and a flux larger than four times the rms noise of the area, or (2) sources with a flux larger than five times the rms noise of the area and without reported counterparts. The authors searched the literature for previous radio detections, and for counterparts at X-ray, optical, near-infrared, and mid-infrared wavelengths. The search was done in SIMBAD, and accessed all the major catalogs (listed explicitly in the footnote of Table 3 in the reference paper). Note that the Spitzer c2d catalog includes cross-references to other major catalogs which were taken into account in their counterpart search. The authors considered a radio source associated with a counterpart at another wavelengths if the separation between the two was below the combined uncertainties of the two data sets. This was about 1.5 arcseconds for the optical and infrared catalogs, but could be significantly larger for some of the radio catalogs (for instance, the NVSS has a positional uncertainty of about 5 arcseconds). The authors found that only 76 of the sources detected here had previously been reported at radio wavelengths (matches are listed in the radio_name parameter in such cases), while the other 113 are new radio detections. On the other hand, they found a total of 100 counterparts at other wavelengths. Note that there are a significant number of sources that were previously known at radio wavelengths and have known counterparts at other frequencies. As a consequence, the number of sources that were previously known (at any frequency) is 134, while 55 of the sources in this sample are reported here for the first time. The authors argue that most of these 55 objects are likely background sources. They note, however, that 18 of the 129 unclassified objects (55 identified here for the first time and 74 previously known at radio wavelengths) are compact, have a positive spectral index, or exhibit high variability. Since these latter two properties are not expected of quasars (which are certainly variable, but usually not strongly on such short timescale), but would be natural characteristics of young stars, the authors argue that a small population of YSOs might be present among the unclassified sources. This population could account for, at most, 15% of the unclassified sources, and possibly significantly less. This table was created by the HEASARC in July 2015 based on electronic versions of Tables 1, 3 and 5 from the reference paper, which were obtained from the CDS (Catalog J/ApJ/775/63 files table1.dat, table3.dat and table5.dat). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlagbsori
- Title:
- VLA Goulds Belt Survey Orion Complex Source Catalog
- Short Name:
- VLAGBSORI
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from a high-sensitivity (60 µJy), large-scale (2.26 deg<sup>2</sup>) survey obtained with the Karl G. Jansky Very Large Array (JVLA) as part of the Gould's Belt Survey (GBS) program. The authors detected 374 and 354 sources at 4.5 and 7.5 GHz, respectively. Of these, 148 are associated with previously known young stellar objects (YSOs). Another 86 sources previously unclassified at either optical or infrared wavelengths exhibit radio properties that are consistent with those of young stars. The overall properties of these sources at radio wavelengths such as their variability and radio to X-ray luminosity relation are consistent with previous results from the GBS. These detections provide target lists for follow-up Very Long Baseline Array radio observations to determine their distances, as YSOs are located in regions of high nebulosity and extinction, making it difficult to measure their optical parallaxes. The observations were obtained with the JVLA of the National Radio Astronomy Observatory (NRAO) in its A configuration. The observations of the 210 fields in the Orion Molecular Clouds A and B were obtained in three different epochs (2011 June 25 to July 4, July 23 to 30, and August 25 to 29, as described in Table 1 of the reference paper) typically separated from one another by a month. The 210 individual fields have been split into 7 maps, with 30 fields being observed per map, as follows: 12 in the lambda Ori region, 3 in L1622, 27 are shared between NGC 2068 and NGC 2071, 14 are shared between NGC 2023 and NGC 2024, 11 in the sigma Ori region, 109 in the Orion Nebula Cluster (ONC), 16 in L1641-N, 8 in L1641-C, and 10 in L1641-S (see Figures 1 to 7 in the reference paper). Two frequency sub-bands, each 1-GHz wide, and centered at 4.5 and 7.5 GHz, respectively, were recorded simultaneously. The authors achieved a nearly uniform rms noise of 60 µJy beam<sup>-1</sup> at both frequencies in all the regions. The only exception to this is in the Trapezium region due to nebular emission; there the noise was 200 µJy beam<sup>-1</sup> after excluding baselines smaller than 150 kilo-lambda during imaging to remove extended emission. Sources were identified through a visual inspection of the individual fields at 4.5 GHz during the cleaning and imaging process since an automated source identification was deemed to be not sufficiently advanced and produced results that were too unreliable. In particularly clustered regions such as the Trapezium and NGC 2024, in addition to standard imaging, data from all three epochs were combined into a single image for source identification purposes only to improve statistical significance of each detection. The authors detected a combined total of 374 sources among the three epochs for all of the regions. All sources but one had fluxes greater than five times the rms noise in at least one epoch. The remaining source, 'GBS-VLA J053518.67-052033.1', was detected at two epochs with maximum detection probability of 4.9 sigma in a single epoch data. It is found in the Trapezium region, and has known counterparts in other wavelength regimes. The authors cross-referenced their catalog of sources with previous major radio, infrared, optical and X-ray surveys of the regions published in the literature. They have generally considered sources in these surveys to be counterparts if they had positional coincidences less than 1 arcsecond, but have allowed for larger offsets if the combined uncertainty between the databases was large. Of 374 detected sources, 261 have been previously found at another wavelength region, while 113 are new detections. 146 sources have been detected in X-rays, 94 at optical wavelengths, 218 at infrared, and 63 in previous radio surveys. Of the previously identified sources, 1 is extragalactic, while the other 148 as young stellar objects (YSOs). Of the YSOs, 106 have been placed on the standard class system based on the IRAC color-color classification of Allen et al. (2004, ApJS, 154, 363). There are 11 Class 0/I, 26 Class II, and 70 Class III type stars. A total of 225 sources are either new detections or, to the authors' knowledge, have not been previously classified in the literature. Of these remaining objects, they have identified 86 as exhibiting variability or high levels of circular polarization. While the authors cannot exclude the possibility that any of them are extragalactic in nature, quasars are not expected to vary as strongly on timescales of few weeks to few months, and exhibit very weak circular polarization, so these sources (listed in Table 5 of the reference paper) are likely YSO candidates. Using the same criteria of variability and circular polarization would identify only 107 of the 148 previously-known YSOs; thus we cannot tell which of the remaining 139 unidentified sources are YSOs or extragalactic objects. This table was created by the HEASARC in July 2015 based on electronic versions of Tables 2 and 4 from the reference paper, which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlagbsser
- Title:
- VLA Goulds Belt Survey Serpens Region Source Catalog
- Short Name:
- VLAGBSSER
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from a deep (~17 µJy) radio continuum observations of the Serpens molecular cloud, the Serpens south cluster, and the W40 region that were obtained using the Jansky Very Large Array (JVLA) in its A configuration. The authors detected a total of 146 sources, 29 of which are young stellar objects (YSOs), 2 of which are BV stars, and 5 more of which are associated with phenomena related to YSOs. Based on their radio variability and spectral index, the authors propose that about 16 of the remaining 110 unclassified sources are also YSOs. For approximately 65% of the known YSOs detected here as radio sources, the emission is most likely non-thermal and related to stellar coronal activity. As also recently observed in Ophiuchus, this sample of YSOs with X-ray counterparts lies below the fiducial Guedel & Benz (1993, ApJ, 405, L63) relation. In the reference paper, the authors analyze the proper motions of nine sources in the W40 region, thus allowing them to better constrain the membership of the radio sources in the region. The Serpens molecular cloud and the Serpens South cluster were observed in the same observing sessions on three different epochs (2011 June 17, July 19, and September 12 UT), using 25 and 4 pointings, respectively, with the JVLA at 4.5 and 4.5GHz. The W40 region, on the other hand, was only observed on two epochs (2011 June 17 and July 16), using 13 pointings. The details of the observations are listed in Table 1 of the reference paper. The authors adopted the same criteria as Dzib et al. (2013, ApJ, 775, 63) to consider a detection as firm. For new sources, i.e., those without reported counterparts in the literature, they considered 5-sigma detections, where sigma is the rms noise of the area around the source. For known sources with counterparts in the literature, on the other hand, they included 4-sigma detections. According to these criteria, they detected 94 sources in the Serpens molecular cloud, 41 in the W40 region, and 8 in the Serpens South cluster, for a total of 143 detections. Out of the 143 sources, 69 are new detections (see Section 3.2 of the reference paper). GBS-VLA source positions were compared with source positions from X-ray, optical, near-IR, mid-IR, and radio catalogs. GBS-VLA sources were considered to have a counterpart at another wavelength when the positional coincidences were better than the combined uncertainties of the two data sets. These were about 1 arcsecond for the IR catalogs. For the X-ray and radio catalogs it depended on the instrument and its configuration. The search was done in SIMBAD and included all the major catalogs. The authors also accessed the lists with all YSOs in the c2d-GB clouds compiled by Dunham et al.(2013, AJ, 145, 94) and L.E. Allen et al. (2015, in preparation). In total, 354 c2d-GB sources lie inside the regions observed by the present survey. In order to find their radio counterparts, the authors imaged regions of 64 pixels in each dimension, centered in the c2d-GB positions, and combining accordingly with each region, the three or two epochs. For this search, they only used the field whose phase center was closest to the source. Three additional radio sources were found in Serpens South in this pursuit, increasing the number of the radio detections to 146. This table was created by the HEASARC in October 2015 based on electronic versions of Tables 2, 3 and 6 from the reference paper, which were obtained from the CDS (Catalog J/ApJ/805/9 files table2.dat, table3.dat and table6.dat). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/vlagbstau
- Title:
- VLA Goulds Belt Survey Taurus-Auriga Complex Source Catalog
- Short Name:
- VLAGBSTAU
- Date:
- 11 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from a multi-epoch radio study of the Taurus-Auriga complex made with the Karl G. Jansky Very Large Array (JVLA) at frequencies of 4.5 GHz and 7.5 GHz. A total of 610 sources were detected, 59 of which are related to young stellar objects (YSOs) and 18 to field stars. The properties of 56% of the young stars are compatible with non-thermal radio emission. The authors also show that the radio emission of more evolved YSOs tends to be more non-thermal in origin and, in general, that their radio properties are compatible with those found in other star-forming regions. By comparing their results with previously reported X-ray observations, the authors noticed that YSOs in Taurus-Auriga follow a Guedel-Benz relation with a scaling factor, kappa, of 0.03, as they previously suggested for other regions of star formation. In general, YSOs in Taurus-Auriga and in all the previous studied regions seem to follow this relation with a dispersion of ~1 dex. Finally, the authors propose that most of the remaining sources are related with extragalactic objects but provide a list of 46 unidentified radio sources whose radio properties are compatible with a YSO nature (identified in this implementation of their catalog by values for the parameter radio_yso_flag of 'Y'). The observations were obtained with the JVLA of the National Radio Astronomy Observatory (NRAO) in its B and BnA configuration. Two frequency sub-bands, each 1 GHz wide, and centered at 4.5 and 7.5 GHz, respectively, were recorded simultaneously. The observations were obtained in three different time periods (February 25/26/28 to March 6, April 12/17/20/25, and April 30 to May 1/5/14/22, all in 2011) typically separated from one another by a month: see Table 1 of the reference paper for more details. For their study, the authors observed 127 different target fields distributed across the cloud complex (Figure 1 of the reference paper). The fields were chosen to cover previously known YSOs. In 33 of those fields, the authors could observe more than one YSO target, while in the remaining 94 fields, only one YSO was targeted. In most cases, the infrared evolutionary class (i.e., Classes I, II, or III) or T Tauri evolutionary status (classical or weak line) of the targeted sources was known from the literature. The final images covered circular areas of 8.8 and 14.3 arcminutes in diameter, for the 7.5 and 4.5 GHz sub-bands, respectively, and were corrected for the effects of the position-dependent primary beam response. The noise levels reached for each individual observation was about ~40 µJy and ~30 µJy, at 4.5 GHz and7.5 GHz, respectively. The visibilities of the three, or two, observations obtained for each field were concatenated to produce a new image with a lower noise level (of about ~25 µJy at 4.5 GHz and ~18 µJy at 7.5 GHz). The angular resolution of ~1 arcsecond (see the synthesized beam sizes in Table 1 of the reference paper) allows an uncertainty in position of ~0.1 arcseconds or better. In the observed area, there are a total of 196 known YSOs.The first step was the identification of radio sources in the observed fields. The authors follow the procedure and criteria presented by Dzib et al. (2013, ApJ, 775, 63) who consider a detection as firm if the sources have a flux larger than 4 times the noise level and there is a counterpart known at another wavelength, else they require a flux which is 5 times the noise level. The identification was done using the images corresponding to the concatenation of the observed epochs, which provides the highest sensitivity. From this, a total of 609 sources were detected. Of these sources, 215 were only detected in the 4.5 GHz sub-band, while six were only detected in the 7.5 GHz sub-band. The remaining 388 sources were detected in both sub-bands. The authors searched the literature for previous radio detections, and for counterparts at X-ray, optical, near-infrared, and mid-infrared wavelengths. The search was done using SIMBAD, and accessed all the major catalogs. They considered a radio source to be associated with a counterpart at another wavelength if the separation between the two was below the combined uncertainties of the two data sets. This was about 1.0 arcsecond for the optical and infrared catalogs, but could be significantly larger for some of the radio catalogs (for instance, the NVSS has a positional uncertainty of about 5 arcseconds). They found that only 120 of the sources detected here had previously been reported at radio wavelengths, while the other 491 are new radio detections. On the other hand, the authors found a total of 270 counterparts at other wavelengths. In the literature, 18 are classified as field stars, 49 as extragalactic, 1 is classified as either a star or an extragalactic source in different surveys, 49 are classified as YSOs, 11 are classified as either YSO and extragalactic, and the remaining 143 sources are unclassified. Note that 56 sources were previously known at radio wavelengths but do not have known counterparts at other frequencies. As a consequence, the number of sources that were previously known (at any frequency) is 327, while 284 of the sources in this sample are reported here for the first time. This table was created by the HEASARC in July 2015 based on electronic versions of Tables 1, 4 and 5 from the reference paper, which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
